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  • 1. Agrell, J.
    et al.
    Birgersson, H.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Steam reforming of methanol over a Cu/ZnO/Al2O3 catalyst: a kinetic analysis and strategies for suppression of CO formation2002In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 106, no 1-2, p. 249-257Conference paper (Refereed)
    Abstract [en]

    Steam reforming of methanol (CH3OH + H2O --> CO2 + 3H(2)) was studied over a commercial Cu/ZnO/Al2O3 catalyst for production of hydrogen onboard proton exchange membrane (PEM) fuel cell vehicles. A simple power-law rate expression was fitted to experimental data in order to predict the rates Of CO2 and H-2 formation under various reaction conditions. The apparent activation energy (E-a) was estimated to be 100.9 kJ mol(-1), in good agreement with values reported in the literature. Appreciable amounts of CO by-product were formed in the reforming process at low contact times and high methanol conversions. Being a catalyst poison that deactivates the electrocatalyst at the fuel cell anode at concentrations exceeding a few ppm, special attention was paid to the pathways for CO formation and strategies for its suppression. It was found that increasing the steam-methanol ratio effectively decreases CO formation. Likewise, addition of oxygen or air to the steam-methanol mixture minimises the production of CO. By shortening the contact time and lowering the maximum temperature in the reactor, CO production can be further decreased by suppressing the reverse water-gas shift reaction.

  • 2. Agrell, J.
    et al.
    Birgersson, H.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Melian-Cabrera, I.
    Navarro, R. M.
    Fierro, J. L. G.
    Production of hydrogen from methanol over Cu/ZnO catalysts promoted by ZrO2 and Al2O32003In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 219, no 2, p. 389-403Article in journal (Refereed)
    Abstract [en]

    Production of H-2 from methanol by steam reforming, partial oxidation, or a combination thereof was studied over Cu/ZnO-based catalysts. The catalysts were characterized by a variety of techniques, including N2O chemisorption, X-ray photoelectron spectroscopy, X-ray diffraction, and temperature-programmed reduction/oxidation. The influence of feed composition, reaction temperature, and catalyst formulation on H-2 production rate, product distribution, and catalyst lifetime was investigated. Distinct differences between the processes were observed with respect to catalyst behavior. ZrO2-containing catalysts, especially Cu/ZnO/ZrO2/Al2O3, exhibit the best performance in the steam reforming reaction. During partial oxidation, however, a binary Cu/ZnO catalyst exhibits the lowest light-off temperature and the lowest level of CO by-product. The redox properties of the catalyst appear to play a key role in determining the pathway for H-2 production. In particular. the extent of methanol and/or H-2 combustion at differential O-2 conversion is strongly dependent on the ease of copper oxidation in the catalyst.

  • 3. Agrell, J.
    et al.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Fierro, J. L. G.
    Production of hydrogen from methanol over binary Cu/ZnO catalysts - Part II. Catalytic activity and reaction pathways2003In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 253, no 1, p. 213-223Article in journal (Refereed)
    Abstract [en]

    The activity for conversion of methanol into hydrogen was investigated over binary Cu/ZnO catalysts derived from precursors prepared by two different techniques, viz. oxalates formed in microemulsion and hydroxycarbonates formed in aqueous solution. Some distinct differences in the reaction pathways were observed. During partial oxidation of methanol under a sub-stoichiometric oxygen/methanol ratio, the microemulsion materials exhibited considerably higher combustion activity in the low-temperature region than a catalyst prepared in aqueous solution. Over the former, oxygen was quickly converted by methanol combustion, after which steam reforming was initiated, producing hydrogen at the expense of water and gradually decreasing the net heat of reaction. Hence, a reaction sequence for the partial oxidation reaction over microemulsion catalysts is proposed. consisting of consecutive methanol combustion and steam reforming, followed by decomposition when all oxygen has been consumed. Over the hydroxycarbonate catalyst, the reaction ignited at a higher temperature, directly producing hydrogen by partial oxidation of methanol. When the two types of catalysts were evaluated in the steam reforming reaction, all catalysts displayed the typical S-shaped dependence of methanol conversion on temperature. However, there was a downward shift in the temperature at which methanol reached complete conversion, favouring the hydroxycarbonate, material. Hydrogen was produced selectively over all catalysts, but carbon monoxide formation was more pronounced over the microemulsion materials. The differences in catalytic behaviour are discussed in terms of catalyst morphology and the valence state of Cu in the working catalyst.

  • 4. Agrell, J.
    et al.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Melian-Cabrera, I.
    Fierro, J. L. G.
    Production of hydrogen from methanol over binary Cu/ZnO catalysts - Part I. Catalyst preparation and characterisation2003In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 253, no 1, p. 201-211Article in journal (Refereed)
    Abstract [en]

    Mixed copper-zinc oxide catalysts (Cu/ZnO) were prepared by two different techniques, i.e. from hydroxycarbonate precursors formed in aqueous solution and from oxalate precursors formed in water-in-oil microemulsion. Their physicochemical properties were characterised by nitrogen adsorption-desorption, N2O chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and oxidation (TPO). The BET surface areas ranged from 34 to 87 m(2)/g, depending on the method of preparation. Cu surface areas between 6.6 and 22 m(2)/g were measured. It was a general observation that catalysts prepared by microemulsion technique had lower Cu dispersions than expected (3.4-5.7%), due to a proposed partial embedding of Cu in ZnO. The catalyst prepared by carbonate co-precipitation exhibited a significantly higher Cu dispersion (10.3%). In addition, this catalyst displayed better resistance to successive TPR/TPO than the microemulsion catalysts, which exhibited significant Cu crystallite growth. However, the microemulsion route provided well-mixed materials with a narrow particle size distribution and the possibility to obtain high BET surface areas (up to 87 m(2)/g) by controlling the water/surfactant ratio in the microemulsion. XPS measurements revealed the existence of Cu+ species on the surface of both types of catalysts after exposure to a O-2/CH3OH mixture. The surface composition of the hydroxycarbonate-derived sample was unaffected by reduction in hydrogen and exposure to O-2/CH3OH, while Zn-enrichment on the surface was observed in the microemulsion catalysts after reduction, indicating sintering of the Cu particles. These observations were consistent with the TPR/TPO measurements.

  • 5. Agrell, J.
    et al.
    Germani, G.
    Järås, Sven G.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Production of hydrogen by partial oxidation of methanol over ZnO-supported palladium catalysts prepared by microemulsion technique2003In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 242, no 2, p. 233-245Article in journal (Refereed)
    Abstract [en]

    Selective production of hydrogen by partial oxidation of methanol, using air as oxidant, was studied over a series of ZnO-supported Pd catalysts. Microemulsion-assisted synthesis and conventional impregnation techniques were used for preparation of catalysts containing Pd particles of different sizes. Catalyst characterisation included BET, XRD and TEM analyses. The influence of Pd particle size on catalytic activity and product distribution was studied by carrying out activity measurements at temperatures between 230 and 300 degreesC using a stoichiometric feed composition. All catalysts performed well with respect to methanol conversion and hydrogen yield. Both methanol conversion and hydrogen selectivity increased with increasing reaction temperature, the latter at the expense of water formation. Oxygen conversion was complete throughout the examined temperature range. These selectivity trends, with a strong dependence of hydrogen and carbon monoxide selectivities on methanol conversion and reaction temperature, support a reaction scheme consisting of consecutive methanol combustion, steam reforming and decomposition. More importantly, a correlation between Pd particle size and carbon monoxide selectivity was found. When the microemulsion catalysts are compared, carbon monoxide formation increases with increasing particle size. This was not observed over the impregnated reference catalysts, which exhibited high carbon monoxide-levels throughout the examined temperature range. Bimetallic PdZn particles were detected in spent catalysts by means of XRD and it is suggested that the catalytic activity is dependent on the formation of PdZn, the catalytic function being different from that of Pd-0.

  • 6. Agrell, J.
    et al.
    Hasselbo, K.
    Jansson, K.
    Järås, Sven G.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Production of hydrogen by partial oxidation of methanol over Cu/ZnO catalysts prepared by microemulsion technique2001In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 211, no 2, p. 239-250Article in journal (Refereed)
    Abstract [en]

    Production of hydrogen by partial oxidation of methanol, using air as oxidant. has been studied over a series of Cu/ZnO catalysts prepared by microemulsion technique. The catalytic activity was compared to that of a reference catalyst prepared by conventional co-precipitation. The BET surface areas of the microemulsion catalysts (30-70 wt.% Cu) ranged from 22 to 36 m(2)/g and were considerably lower than that of the reference (60 m(2)/g). Nevertheless, the microemulsion catalysts were more active in the partial oxidation reaction and exhibited high hydrogen and carbon dioxide selectivities. At a molar O-2/CH3OH ratio of 0.1, hydrogen production was initiated at about 185 degreesC over the microemulsion catalysts. Over the reference, hydrogen production began at 215 degreesC under the same conditions. The catalytic activity was Found to be strongly dependent on the partial pressure of oxygen, which also plays an important role in determining the product distribution. By increasing the O-2/CH3OH ratio, the methanol conversion and carbon dioxide selectivity increase. while production of water occurs at the expense of hydrogen. By TEM and TPR, it was observed that Cu is less well-dispersed in the microemulsion catalysts than in the reference. The higher catalytic activity is not expected considering the lower number of exposed Cu sites, i.e, the turnover frequencies are substantially higher over the microemulsion catalysts. It is possible that, a strong interaction between a small part of CuO and the ZnO lattice is responsible for the higher turnover frequencies of the microemulsion catalysts, or that particular crystallographic Cu planes or surface imperfections are the active sites of the reaction.

  • 7.
    Andersson, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Correlation patterns and effect of syngas conversion level for product selectivity to alcohols and hydrocarbons over molybdenum sulfide based catalysts2012In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 417, p. 119-128Article in journal (Refereed)
    Abstract [en]

    The focus of the present study was to investigate the effect of the operation conditions, space velocity and temperature, on product distribution for a K-Ni-MoS2 catalyst for mixed alcohol synthesis from syngas. All experiments were performed at 91 bar pressure and constant H-2/CO=1 syngas feed ratio. For comparison, results from a non-promoted MoS2 catalyst are presented. It was found that the CO conversion level for the K-Ni-MoS2 catalyst very much decides the alcohol and hydrocarbon selectivities. Increased CO conversion by means of increased temperature (tested between 330 and 370 degrees C) or decreased space velocity (tested between 2400 and 18,000 ml/(g(cat) h)), both have the same effect on the product distribution with decreased alcohol selectivity and increased hydrocarbon selectivity. Increased CO conversion also leads to a greater long-to-short alcohol chain ratio. This indicates that shorter alcohols are building blocks for longer alcohols and that those alcohols can be converted to hydrocarbons by secondary reactions. At high temperature (370 degrees C) and low space velocity (2400 ml/(g(cat) h)) the selectivity to isobutanol is much greater than previously reported (9%C). The promoted catalyst (K-Ni-MoS2) is also compared to a non-promoted (MoS2) catalyst: the promoted catalyst has quite high alcohol selectivity, while almost only hydrocarbons are produced with the non-promoted catalyst. Another essential difference between the two catalysts is that the paraffin to olefin ratio within the hydrocarbon group is significantly different. For the non-promoted catalyst virtually no olefins are produced, only paraffins, while the promoted catalyst produces approximately equal amounts of C-2-C-6 olefins and paraffins. Indications of olefins being produced by dehydration of alcohols were found. The selectivity to other non-alcohol oxygenates (mostly short esters and aldehydes) is between 5 and 10%C and varies little with space velocity but decreases slightly with increased temperature. Very strong correlation patterns (identical chain growth probability) and identical deviations under certain reaction conditions between aldehyde and alcohol selectivities (for the same carbon chain length) indicate that they derive from the same intermediate. Also olefin selectivity is correlated to alcohol selectivity, but the correlation is not as strong as between aldehydes and alcohols. The selectivity to an ester is correlated to the selectivity to the two corresponding alcohols, in the same way as an ester can be thought of as built from two alcohol chains put together (with some H-2 removed). This means that, e.g. methyl acetate selectivity (C-3) is correlated to the combination of methanol (C-1) and ethanol (C-2) selectivities.

  • 8.
    Andersson, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Effect of CO2 in the synthesis of mixed alcohols from syngas over a K/Ni/MoS2 catalyst2013In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 107, p. 715-723Article in journal (Refereed)
    Abstract [en]

    An unsupported K-Ni-MoS2 catalyst for higher alcohol synthesis from syngas (H-2/CO) has been studied during 360 h on stream. It shows a gradual increase in activity with time on stream and some possible reasons for this are discussed in the paper. The main focus of this paper was to study the on the effect of CO2-containing syngas, relative CO2-free syngas under identical reaction conditions and identical inlet H-2 and CO partial pressures (340 degrees C, 100 bar, GHSV = 6920 ml/(g(cat) h)). The effect of increased partial pressure of H-2 and CO was also studied, and to a minor extent also the effect of changed gas hourly space velocity (GHSV). Under the studied conditions, addition of CO2 was found to greatly decrease total product yield, while the selectivities to alcohol and hydrocarbons (C%, CO2-free), respectively, were unchanged. CO2 addition, however, led to a great change in the distribution within the alcohol and hydrocarbon groups. With CO2 added the methanol selectivity increased much while selectivity to longer alcohols decreased. For hydrocarbons the effect is the same, the selectivity to methane is increased while the selectivity to longer hydrocarbons is decreased. It has earlier been shown that product selectivities are greatly affected by syngas conversion level (correlated to outlet concentration of organic products, i.e. alcohols, hydrocarbons etc.) which can be altered by changes in space velocity or temperature. This means that alcohol selectivity is decreased in favor of increased hydrocarbon selectivity and longer alcohol-to-methanol ratio when syngas conversion is increased. At first it might be thought that the selectivity changes occurring when CO2 is present in the feed, just correlate to a decreased organic product concentration in the reactor and that the selectivities with CO2-containing and CO2-free syngas would be identical under constant concentration of organic products in the reactor. However, CO2-addition studies where space velocity was varied showed that significantly lower alcohol selectivity (mainly ethanol selectivity) and increased hydrocarbon selectivity (mainly methane) were found at similar organic outlet concentrations as when CO2-free syngas was feed. Comparing addition of extra H-2 or extra CO, it was found that a high H-2/CO ratio (H-2/CO = 1.52 tested in our case) favors maximum product yield, especially methanol formation, while a lower H-2/CO ratio (H-2/CO = 0.66 tested in our case) leads to higher yield of higher alcohols simultaneously minimizing hydrocarbon and methanol formation.

  • 9.
    Andersson, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Higher alcohols from syngas using a K/Ni/MoS2 catalyst: Trace sulfur in the product and effect of H2S-containing feed2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 115, p. 544-550Article in journal (Refereed)
    Abstract [en]

    Two types of experiments have been performed related to the higher alcohol synthesis from syngas over a K-Ni-MoS2 catalyst which beforehand has been operated for 1000 h on stream in sulfur-free syngas. In the first experimental part, sulfur-free syngas was used as feed and the condensed liquid product was found to contain 67 ppmw sulfur, while the sulfur concentration in the gas was 19 ppmv. The gas phase was found to contain mainly COS and H2S, while the liquid phase contained methanethiol (13.8 ppmw S), ethanethiol (10.6 ppmw S), dimethyl sulfide (21.3 ppmw S), ethyl methyl sulfide (12.2 ppmw S), unidentified sulfur compounds (7.9 ppmw S) together with some dissolved COS (0.5 ppmw S) and H2S (1.2 ppmw S). In the second experimental part, the effect of feeding syngas containing 170 ppm H2S compared to a sulfur-free syngas was studied, while all products were carefully monitored online. The presence of H2S in the syngas was found to increase CO conversion, but the largest change was found in product selectivity. The hydrocarbon selectivity greatly increased at the expense of alcohol selectivity, while the alcohol distribution shifted towards longer alcohols (increased C2+OH/MeOH ratio). From product yields it became clear that most of the increased CO conversion with H2S in the feed was due to increased methane formation (and CO2 formation due to the water-gas shift reaction). The presence of H2S in the feed greatly increased the concentration of all sulfur compounds. Together with COS, formation of thiols (methanethiol and ethanethiol) was especially favored by the presence of H2S. The thioether concentration also increased, however, to a much lower extent.

  • 10.
    Andersson, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    On-line gas chromatographic analysis of higher alcohol synthesis products from syngas2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1247, p. 134-145Article in journal (Refereed)
    Abstract [en]

    An on-line gas chromatographic (GC) system has been developed for rapid and accurate product analysis in catalytic conversion of syngas (a mixture of H-2 and CO) to alcohols, so called "higher alcohol synthesis (HAS)". Conversion of syngas to higher alcohols is an interesting second step in the route of converting coal, natural gas and possibly biomass to liquid alcohol fuel and chemicals. The presented GC system and method are developed for analysis of the products formed from syngas using alkali promoted MoS2 catalysts, however it is not limited to these types of catalysts. During higher alcohol synthesis not only the wanted short alcohols (similar to C-2-C-5) are produced, but also a great number of other products in smaller or greater amounts, they are mainly short hydrocarbons (olefins, paraffins, branched, non-branched), aldehydes, esters and ketones as well as CO2, H2O. Trace amounts of sulfur-containing compounds can also be found in the product effluent when sulfur-containing catalysts are used and/or sulfur-containing syngas is feed. In the presented GC system, most of them can be separated and analyzed within 60 min without the use of cryogenic cooling. Previously, product analysis in "higher alcohol synthesis" has in most cases been carried out partly on-line and partly off-line, where the light gases (gases at room temp) are analyzed on-line and liquid products (liquid at room temp) are collected in a trap for later analysis off-line. This method suffers from many drawbacks compared to a complete on-line GC system. In this paper an on-line system using an Agilent 7890 gas chromatograph equipped with two flame ionization detectors (FID) and a thermal conductivity detector (TCD), together with an Agilent 6890 with sulfur chemiluminescence dual plasma detector (SCD) is presented. A two-dimensional GC system with Deans switch (heart-cut) and two capillary columns (HP-FFAP and HP-Al2O3) was used for analysis of the organic products on the FIDs. Light inorganic gases (H-2, CO, CO2, N-2) and methane were separated on packed columns and quantified with the TCD. The "sulfur GC" was optimized for on-line trace level sulfur analysis in hydrocarbon matrices and used to understand to which degree sulfur is released from the catalyst and incorporated into the liquid product, and if so in which form. The method provides excellent quantitative measurements with a carbon material balance near 99.5% (carbon in/carbon out) for individual measurement points.

  • 11.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Garcilaso, Victoria
    Venezia, Baldassarre
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Aho, Atte
    Antonio Odriozola, Jose
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Fischer-Tropsch Synthesis Over Zr-Promoted Co/gamma-Al2O3 Catalysts2017In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 60, no 17-18, p. 1285-1298Article in journal (Refereed)
    Abstract [en]

    Two Zr-modified alumina supports were synthetized containing the same amount of Zr but a different distribution of this modifier over the alumina surface. These supports, together with the unmodified alumina carrier, were used to prepare three cobalt-based catalysts which were characterized and tested under relevant Fischer-Tropsch conditions. The three catalysts presented very similar porosity and cobalt dispersion. The addition of Zr nor its distribution enhanced the catalyst reducibility. The catalyst activity was superior when using a carrier consisting of large ZrO2 islands over the alumina surface. The use of a carrier with a homogeneous Zr distribution had however, a detrimental effect. Moreover, a faster initial deactivation rate was observed for the Zr-promoted catalysts, fact that may explain this contradictory effect of Zr on activity. Finally, the addition of Zr showed a clear enhancement of the selectivity to long chain hydrocarbons and ethylene, especially when Zr was well dispersed.

  • 12.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Gonzalez, Niklas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Deactivation of Ni/gamma-Al2O3 Catalysts in CO Methanation: Effect of Zr, Mg, Ba and Ca Oxide Promoters2017In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 60, no 17-18, p. 1276-1284Article in journal (Refereed)
    Abstract [en]

    Catalyst deactivation is one of the major concerns in the production of substitute natural gas (SNG) via CO methanation. Catalysts in this application need to be active at low temperatures, resistant to polymeric carbon formation and stable at high temperatures and steam partial pressures. In the present work, a series of alumina-supported nickel catalysts promoted with Zr, Mg, Ba or Ca oxides were investigated. The catalysts were tested under low temperature CO methanation conditions in order to evaluate their resistance to carbon formation. The catalysts were also exposed to accelerated ageing conditions at high temperatures in order to study their thermal stability. The aged catalysts lost most of their activity mainly due to sintering of the support and the nickel crystallites. Apparently, none of these promoters had a satisfactory effect on the thermal resistance of the catalyst. Nevertheless, it was found that the presence of Zr can reduce the rate of polymeric carbon formation.

  • 13.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    González, N.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    The effect of catalyst pellet size on nickel carbonyl-induced particle sintering under low temperature CO methanation2016In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 514, p. 91-102Article in journal (Refereed)
    Abstract [en]

    Abstract The present work aims to evaluate the effect of catalyst pellet size on deactivation due to nickel carbonyl-induced particle sintering. For that purpose, a γ-Al2O3-supported nickel catalyst was prepared and tested under low temperature and high CO partial pressure. A total of four different pellet sizes were employed in the present study. It was found that the deactivation rate decreases with increasing pellet size. A very severe deactivation was observed when using small pellets. Large pellets exhibited instead a more stable performance. This difference in catalyst stability was explained by X-ray diffraction analyses which revealed that the growth of the nickel particles was very severe when using small pellets. An evaluation of heat and mass transfer phenomena in these four pellets was also conducted. It was found that, under the present low temperature reaction conditions, the temperature at the catalyst external surface can greatly differ from that in the bulk gas when using sufficiently large pellets. It was also shown that, for large pellets, the major part of the interior of the catalyst is exposed to negligible CO partial pressures and high temperatures, fact that can reduce the potential for nickel carbonyl formation.

  • 14.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Deactivation of supported nickel catalysts during CO methanation2014In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 486, p. 143-149Article in journal (Refereed)
    Abstract [en]

    Deactivation of Ni-based catalysts was investigated during CO methanation over different supported catalysts. X-ray diffraction and temperature-programmed hydrogenation analyses were used to investigate nickel particle sintering and carbon formation during the first 24 h on stream. Titania-supported catalysts presented high resistance towards carbon deposition and nickel particle growth in comparison with the other tested catalysts. Particle size effects on these two deactivation causes were also evaluated. It was shown that carbon formation rates are higher on bigger crystal particles. However, it was found that titania-supported nickel catalysts reduced at high temperatures show the opposite effect. This difference is most probably due to a stronger interaction between nickel and TiOx (x < 2) species on smaller crystals which changes the CO dissociation properties and, in consequence, carbon formation rates.

  • 15.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Suarez Paris, Rodrigo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Montes, V.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Jaras, S.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    CO methanation over TiO2-supported nickel catalysts: A carbon formation study2015In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 502, p. 276-286Article in journal (Refereed)
    Abstract [en]

    A systematic study on titania-supported nickel catalysts was performed in order to evaluate the effect of different process conditions on catalyst stability. Reaction tests and temperature-programmed-hydrogenation analyses were used in order to evaluate the effect of temperature, feed composition, water and reduction conditions on catalyst deactivation and carbon deposition. It was shown that high H-2/CO ratios and syngas partial pressures decrease the rate of carbon formation. Moreover, increasing temperature enhanced the formation of more stable carbon species and thus catalyst deactivation. The temperature-programmed hydrogenation analyses also revealed that water reduces the rate of carbon deposition. However, water enhanced catalyst deactivation when the catalysts were reduced at high temperatures. This negative effect of water is probably due to a progressive destruction of the strong-metal-support interaction characteristic of titania-supported nickel catalysts reduced at high temperatures. (C) 2015 Elsevier B.V. All rights reserved.

  • 16.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Montes, V.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Further insights into the effect of sulfur on the activity and selectivity of cobalt-based Fischer–Tropsch catalysts2016In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 275, p. 119-126Article in journal (Refereed)
    Abstract [en]

     A sulfur poisoning study was performed by ex situ poisoning of a platinum-promoted cobalt/alumina catalyst with different sulfur amounts. The poisoned catalyst samples were tested at relevant Fischer–Tropsch reaction conditions and at the same CO conversion in order to evaluate the effect of sulfur on catalyst activity and product selectivity. It was found that the activity and the selectivity to long-chain hydrocarbons decrease with increasing sulfur content. Moreover, it was found that sulfur has no significant effect on the CO2 selectivity. It was also shown that sulfur significantly enhances olefin hydrogenation. Finally, a deactivation model relating the catalyst activity and the sulfur to cobalt active site ratio was proposed and used to describe the experimental results.

  • 17.
    Birgersson, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Birgersson, E
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Mathematical Analysis of Thermally Oxy-Chlorine Regenerated Three-Way CatalystsIn: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405Article in journal (Refereed)
  • 18.
    Birgersson, Henrik
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Järås, Sven G.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Eriksson, L.
    Deactivation and regeneration of spent three-way automotive exhaust gas catalysts (TWC)2004In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 30-1, no 1-4, p. 433-437Article in journal (Refereed)
    Abstract [en]

    The effect of oxidation, oxy-chlorination and reduction treatments at elevated temperatures on the dispersion of palladium (Pd) and rhodium (Rh) for commercially aged three-way automotive exhaust gas catalysts (TWC) has been investigated. The catalytic activity of treated samples was compared with a reference sample, which was taken from the corresponding aged TWC and tested using a 'mini-cuts' reactor simulating real driving conditions. In the case of oxygen, the improvement of the noble metal dispersion on the catalysts was dependent on the noble metal loading and the degree of metal sintering. Adding chlorine to the oxygen atmosphere facilitates the restructuring of the metals with an improved increase in the noble metal dispersion. The temperature and the composition of the gas used during these thermal treatments proved to be of importance not only to increase the metal dispersion, but also to prevent possible losses of noble metals, in the form of volatile MOxCly compounds. TEM-EDS techniques indicated changes in the size of the largest noble metal agglomerates of Lip to 100 nm in size after thermal gas treatment. BET porosity and XRD analyses were employed to investigate restructuring of the washcoat and showed a decrease in pore size distribution and an increase in surface area.

  • 19.
    Birgersson, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Klingstedt, F
    Yu Murzin, D
    Stefanov, P
    Naydenov, A
    An investigation of a new regeneration method of commercial aged three-way catalysts2006In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 65, p. 93-100Article in journal (Refereed)
    Abstract [en]

    The ability to modify aged three-way catalysts (TWC) by regaining part of the fresh catalyst surface structure has been verified by both bulk and surface-sensitive characterisation techniques. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM/EDX) techniques were applied to fully evaluate the efficiency of a regeneration procedure of commercial three-way catalysts targeting the washcoat surface. The regeneration comprised combined thermal and liquid chlorine treatments. Structural changes of the washcoat were further investigated with nitrogen adsorption-desorption (BET) and Laser Ablation methods. The investigation showed that the regeneration treatments resulted in an enrichment of the washcoat surface with palladium, thereby increasing the number of catalytically active surface sites. Furthermore, the observed removal of phosphorous and sulphur contaminants resulted in an increase of the relative amount of small pores between 1 and 10 nm and washcoat surface area. An increased catalytic activity regarding CO, NOx, and HC emissions was observed after regeneration. providing proof of the proposed concept.

  • 20.
    Birgersson, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Eriksson, L
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Regeneration of spent commercial automotive three-way exhaust gas catalysts (TWC)Article in journal (Other academic)
  • 21.
    Birgersson, Henrik
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Eriksson, L
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Järås, Sven
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Thermal gas treatment to regenerate spent automotive three-way exhaust gas catalysts (TWC)2004In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 54, p. 193-200Article in journal (Refereed)
    Abstract [en]

    The effect of regeneration on the metal dispersion and catalyst activity of commercial automotive three-way catalysts (TWC) in oxygen, hydrogen and oxy-chlorine at elevated temperatures has been investigated. In addition, characterisation of the catalysts has been performed using XRD, TEM, TPR, CO chemisorption and BET surface area measurements. Activity tests on monolith fragments were conducted in a micro-reactor supplied with real exhaust gases. An increase in activity was observed with oxygen treatment on catalysts showing heavy sintering as well as a high noble metal loading. Hydrogen proved to be an ineffective treatment procedure, whereas the addition of chlorine to the oxygen stream resulted in an activity increase even on catalysts less sintered and with lower noble metal contents. A comparison of the XRD and BET profiles showed no or small changes in the washcoat structure compared to fresh catalysts after successful regeneration. The TEM, TPR and CO chemisorption measurements suggest a decrease in the size of the largest noble metal agglomerates on the catalyst surface, as well as some Pd and RhO restructuring. The oxy-chlorine regeneration procedure is shown to be the most efficient, both regarding the catalyst activity and the metal dispersion. An increase in the amount of noble metal particles with a size of 20-70 nm, coupled with a decrease in size of larger clusters up to 100 nm in size, was observed for this treatment.

  • 22.
    Boutonnet, Magali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lögdberg, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Elm Svensson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Recent developments in the application of nanoparticles prepared from w/o microemulsions in heterogeneous catalysis2008In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 13, no 4, p. 270-286Article in journal (Refereed)
    Abstract [en]

    This paper reviews the use of microemulsions, especially the water-in-oil (w/o) microemulsions, for preparation of nanoparticles that are employed as catalyst components in heterogeneous catalytic reactions. The objective is to show the growing interest of using microemulsions in the preparation of different types of materials such as metals, single metal oxides or mixed metal oxides with a broad range of application in heterogeneous catalysis and also in electrocatalysis. In most cases, the catalytic material showed improved catalytic properties as a result of the special synthesis environment created by the microemulsions. Still, research is needed for a better understanding of such beneficial effects. In addition, this method needs improvements in order to produce, in an environmentally friendly way, a suitable amount of material for use in industrial-scale catalytic processes.

  • 23.
    Boutonnet, Magali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Marinas, A.
    Montes, V.
    Suárez-Paris, Rodrigo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sánchez-Domínguez, M.
    Nanocatalysts: Synthesis in Nanostructured Liquid Media and Their Application in Energy and Production of Chemicals2016In: Nanocolloids: A Meeting Point for Scientists and Technologists, Elsevier, 2016, p. 211-246Chapter in book (Refereed)
  • 24.
    Boutonnet, Magali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sanchez-Dominguez, Margarita
    Microemulsion droplets to catalytically active nanoparticles: How the application of colloidal tools in catalysis aims to well designed and efficient catalysts2017In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 285, p. 89-103Article in journal (Refereed)
    Abstract [en]

    In this review, we report the successful application of a colloidal tool, namely microemulsions (ME) in the design of catalysts for various applications. First, a brief introduction to MEs and the water-in-oil (w/o) ME reaction method is given. The first ME formulations used for catalyst synthesis are discussed. Catalytic activity of the materials obtained from those initial studies, both as particles deposited onto a support as well as directly as nanoparticles in ME suspension is described. Then various application examples which highlight several important properties of the catalysts obtained from w/o ME are given. For example, particle size control achieved with ME is very relevant to surface sensitive reactions, whose selectivity depends greatly on metal particle size. Another important aspect is related to the unique microenvironment of MEs which results in specific interactions within the formed materials; this is particularly important for certain catalysts such as mixed oxide particles, conferring them with special properties and enhanced performance. Comparison of activity and selectivity of impregnation-prepared versus ME-prepared materials is given for several catalytic reactions. Finally, the more recently developed oil-in-water (o/w) ME method is described, along with examples of materials obtained by this method as catalysts, including photocatalysis. The different aspects discussed in this review demonstrate the importance of the ME reaction method for the design of nanocatalysts with enhanced activity and selectivity.

  • 25. Di Carlo, Gabriella
    et al.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Venezia, Anna M.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sanchez-Dominguez, Margarita
    Design of Cobalt Nanoparticles with Tailored Structural and Morphological Properties via O/W and W/O Microemulsions and Their Deposition onto Silica2015In: CATALYSTS, ISSN 2073-4344, Vol. 5, no 1, p. 442-459Article in journal (Refereed)
    Abstract [en]

    Cobalt nanostructures with different size and morphology, i.e., spherical nanoparticles, nanorods, and particles arranged into elongated structures, were prepared using micelles and microemulsions as confined reaction media. The syntheses were carried out using three types of systems: aqueous surfactant solutions, oil-in water (O/W), and water-in-oil (W/O) microemulsions. The influence of the surfactant and the precipitating agent used for synthesis was also investigated. For this purpose, cobalt nanostructures were prepared using different non-ionic surfactants, namely Synperonic((R)) 10/6, Pluronic((R)) P123 and a mixture of SPAN 20-TWEEN 80. Three different precipitating agents were used: sodium borohydride, sodium hydroxide, and oxalic acid. Our findings revealed that by changing the type of reaction media as well as the precipitating agent it is possible to modify the shape and size of the cobalt nanostructures. Moreover, the use of O/W microemulsion generates better results in terms of colloidal stability and uniformity of particle size with respect to W/O microemulsion. The different cobalt nanostructures were supported on commercial and mesoporous silica; transmission electron microscopy (TEM) images showed that after deposition the Co nanocrystals remain well dispersed on the silica supports. This behavior suggests their great potential in catalytic applications.

  • 26.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    High-surface-area lanthanum hexaaluminates by carbon templatingArticle in journal (Other academic)
  • 27.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Preparation of hexaaluminate2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for preparing a hexaaluminate. The method comprises the steps of a) providing a porous template material, wherein pores having a pore size of about 5-200 nm form at least about 50% of the total pore volume; b) impregnating the material with a liquid comprising metal elements corresponding to the elements of said hexaaluminate to provide an impregnated material; c) drying the impregnated material to provide a dried material; d) optionally, repeating at least once step b), using the dried material, and step c); e) calcining the dried material in an inert atmosphere to provide a calcined material; and f) recovering the hexaaluminate by removing template material from the calcined material. A composition obtainable by such a method. A catalyst composition comprising a hexaaluminate, wherein the composition has an average surface area of at least about 9 m2/g after ageing of the composition in a moist high-temperature atmosphere. A supported catalyst comprising such a composition. Use of such a composition as a catalyst in a high-temperature application.

  • 28.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Stability of hexaaluminate-based catalysts for high-temperature catalytic combustion of methane2008In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 84, no 1-2, p. 241-250Article in journal (Refereed)
    Abstract [en]

    Lanthanum hexaaluminate with a nominal composition of LaAl11O18 Was used to support 20 wt.% of LaMnO3 and CeO2. LaAl11O18 was prepared through co-precipitation of metal nitrates within the water phase of an isooctane/CFAB/1-butanol microemulsion. The stabilities of the prepared catalysts were assessed by measuring the activities for combustion of methane before and after aging at 1000 degrees C for 100h in air with 10 vol.% H2O. The activities were compared with LaMnAl11O19, due to its well-documented stability. It was shown that by using hydrothermal treatment of the microemulsion, a significantly higher surface area was obtained for the LaAl11O18. For LaMnO3, the reference support (Al2O3) was shown to be superior to LaAl11O18 as support, both in terms of activity and stability. Reactions between LaMnO3 and support were observed for all supports included in the study. For CeO2, LaAl11O18 was superior to Al2O3 as support. Deactivations of the CeO2 catalysts were linked to crystal growth of CeO2. LMHA deactivated strongly during aging; LaMnO3 on Al2O3 and several of the catalysts with CeO2 supported on LaAl11O18 showed a much more stable behavior.

  • 29.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Synthesis of barium hexaaluminate by co-precipitation in microemulsionIn: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312Article in journal (Other academic)
  • 30.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Catalytic combustion of methane over perovskite supported on lanthanum hexaaluminate prepared through the microemulsion method2007In: Studies in Surface Science and Catalysis, ISSN 0167-2991, Vol. 172, p. 465-468Article in journal (Refereed)
  • 31.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Nassos, Stylianos
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Microemulsion synthesis of MgO-supported LaMnO3 for catalytic combustion of methane2006In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 117, no 4, p. 484-490Article in journal (Refereed)
    Abstract [en]

    Catalysts with 20% LaMnO3 supported on MgO have been prepared via CTAB-1-butanol-iso-octane-nitrate salt microemulsion. The preparation method was successfully varied in order to obtain different degrees of interaction between LaMnO3 and MgO as shown by TPR and activity tests after calcination at 900 degrees C. Activity was tested on structured catalysts with 1.5% CH4 in air as test gas giving a GHSV of 100,000 h(-1). The activity was greatly enhanced by supporting LaMnO3 on MgO compared with the bulk LaMnO3. After calcination at 1100 degrees C both the surface area and TPR profiles were similar, indicating that the preparation method is of little importance at this high temperature due to interaction between the phases. Pure LaMmO(3) and MgO were prepared using the same microemulsion method for comparison purposes. Pure MgO showed an impressive thermal stability with a BET surface area exceeding 30 m(2)/g after calcination at 1300 degrees C. The method used to prepare pure LaMnO3 appeared not to be suitable since the surface area dropped to 1.1 m(2)/g already after calcination in 900 degrees C.

  • 32.
    Eriksson, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Catalytic combustion of methane in steam and carbon dioxide-diluted reaction mixtures2006In: Applied Catalysis, ISSN 0166-9834, E-ISSN 1873-3867, Vol. 312, p. 95-101Article in journal (Refereed)
    Abstract [en]

    Supported palladium catalysts have been tested for methane combustion under lean conditions in the temperature range of 200-800 degrees C. The effect of diluting the reaction mixture with high amounts of water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. The influence of support material, i.e. ZrO2 or doped CeO2, on the catalytic performance was also investigated.

    The catalyst support material was found to influence the light-off temperature significantly, which increased in the following order: Pd/ZrO2 < Pd/Zr-CeO2 < Pd/La-CeO2. The order of activity changed at higher temperatures resulting in Pd/La-CeO2 being the most active catalyst above 670 degrees C. This catalyst also shows a more stable performance with no distinct deactivation occurring at higher temperatures during cooling.

    Both water and CO2 were found to have a negative influence on the catalytic activity. The inhibitory effect was, however, more pronounced for water. This inhibitory effect was present in the entire temperature range investigated. Adding CO2 in the presence of water resulted in conversions similar to the ones observed when feeding water alone for Pd/ZrO2 and Pd/La-CeO2, On the contrary, the activity of Pd/Zr-CeO2 was further decreased when co-feeding water and CO2.

  • 33.
    Eriksson, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Nilsson, Martita
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Partial oxidation of methane over rhodium catalysts for power generation applications2005In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 100, p. 447-451Article in journal (Refereed)
    Abstract [en]

    The partial oxidation of methane (POM) to syngas, i.e. H-2 and CO, over supported Rh catalysts was investigated at atmospheric pressure. The influence of support material, Rh loading and the presence of water vapor on the methane conversion efficiency and the product gas composition was studied. The catalysts containing ceria in the support material showed the highest activity and formation of H2 and CO. By increasing the Rh loading, a decrease of the ignition temperature was obtained. The addition of water vapor to the reactant gas mixture was found to increase the ignition temperature and the formation of hydrogen, which is favorable for combustion applications where the catalytic POM stage is followed by H-2-stabilized homogeneous combustion.

  • 34.
    Eriksson, Sara
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Nylén, Ulf
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Rojas, Sergio
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Preparation of catalysts from microemulsions and their applications in heterogeneous catalysis2004In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 265, no 2, p. 207-219Article in journal (Refereed)
    Abstract [en]

    Microemulsions have a wide range of applications from oil recovery to synthesis of nanoparticles. The first implementation of water-in-oil (w/o) microemulsions for synthesis of nanoparticles was introduced in 1982 and concerns nanoparticles of noble metals for catalytic uses. Since this time, the method has been employed quite extensively in the field of catalysis, from room-temperature reactions such as butene isomerisation to high-temperature reactions such as catalytic combustion of methane.The present review paper will introduce the term microemulsion with emphasis on the microemulsion properties essential for heterogeneous catalyst preparation followed by a general description of the mode of catalytic materials prepared from microemulsions. Several examples of the use of these materials in heterogeneous catalysis are then described. It is shown that nanoparticles obtained from microemulsions have specific properties with respect to size, size distribution and surface structure. Consequently, these particles are in some cases superior regarding catalytic activity and/or selectivity

  • 35.
    Eriksson, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rojas, S.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Fierro, J.L.G.
    Effect of Ce-doping on Rh/ZrO2 catalysts for partial oxidation of methane2007In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 326, no 1, p. 8-16-Article in journal (Refereed)
    Abstract [en]

    The partial oxidation of methane over supported (ZrO2, CeO2-ZrO2) rhodium catalysts was investigated at atmospheric pressure. The effect of temperature, CH4/O-2 ratio, catalyst composition and pre-treatment was studied. Ceria doping of the support material resulted in significant improvements concerning the methane conversion and syngas selectivity, which could be related to a higher noble metal dispersion on the Rh/CeO2-ZrO2 catalyst. In addition, the light-off temperature was decreased by 128 degrees C when using CeO2-ZrO2, as support. X-ray photoelectron spectroscopy revealed the presence of different Rh oxidation states depending on catalyst composition and pre-treatment. A stabilization of partially oxidized (Rh delta+) species by ceria could be detected. An active and stable catalyst behavior could be observed for Rh/CeO2-ZrO2, irrespectively of catalyst pre-treatment, whereas an activation period was required for stabilizing the activity of the Rh/ZrO2 catalyst. The activity tests indicate that the indirect reaction mechanism, consisting of methane combustion followed by steam and dry reforming, prevails under the experimental conditions studied.

  • 36.
    Eriksson, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Wolf, M.
    Schneider, A.
    Mantzaras, J.
    Raimondi, F.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Fuel-rich catalytic combustion of methane in zero emissions power generation processes2006In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 117, no 4, p. 447-453Article in journal (Refereed)
    Abstract [en]

    A novel catalytic combustion concept for zero emissions power generation has been investigated. Catalysts consisting of Rh supported on ZrO2, Ce-ZrO2 or alpha-Al2O3 were prepared and tested under fuel-rich conditions, i.e. for catalytic partial oxidation (CPO) of methane. The experiments were performed in a subscale gas-turbine reactor operating at 5 bar with exhaust gas-diluted feed mixtures.The catalyst support material was found to influence the light-off temperature significantly, which increased in the following order Rh/Ce-ZrO2 < Rh/ZrO2 < Rh/alpha-Al2O3. The Rh loading, however, only had a minor influence. The high activity of Rh/Ce-ZrO2 is probably related to the high dispersion of Rh on Ce-ZrO2 and the high oxygen mobility of this support compared to pure ZrO2. The formation of hydrogen was also found to increase over the catalyst containing ceria in the support material.

  • 37. Escudero, M. J.
    et al.
    Hontanon, E.
    Schwartz, S.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Daza, L.
    Development and performance characterisation of new electrocatalysts for PEMFC2002In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 106, no 1-2, p. 206-214Conference paper (Refereed)
    Abstract [en]

    New electrocatalysts based on Pt, Pt-Ru and Pt-Pd have been prepared by the microemulsion method. This method allows the production of a very narrow size distribution of metal particles, with an average size smaller than that of conventional electrocatalysts prepared by impregnation. Eight membrane electrode assemblies (MEAs) with an active surface area of 50 cm(2) were characterised in a single fuel cell. The MEAs consist of Nation 117 as membrane and a commercial electrocatalyst (40% Pt/C from E-TEK) on the cathode side, Four MEAs have electrocatalysts prepared by the microemulsion technique and the other four have commercial electrocatalysts on the anode side. The performance of the eight MEAs was evaluated by measuring the fuel cell polarisation curves and the internal resistance with H-2/O-2 and H-2/air, at 60 T and pressure in the range from I to 3 bar. The MEAs with the electrocatalysts prepared by microemulsion showed a performance comparable to that of the MEAs with commercial electrocatalysts. The satisfactory results obtained show that microemulsion is a promising method for the preparation of electrocatalysts for fuel cells. Further effort will be devoted to the optimisation of the method, mainly, the deposition of the metal particles on the carbon support, which it is expected to enhance the fuel cell performance.

  • 38. Garcilaso, V.
    et al.
    Barrientos, Javier
    KTH.
    Bobadilla, L. F.
    Laguna, O. H.
    Boutonnet, Magali
    KTH.
    Centeno, M. A.
    Odriozola, J. A.
    Promoting effect of CeO2, ZrO2 and Ce/Zr mixed oxides on Co/Γ-Al2O3 catalyst for Fischer-Tropsch synthesis2019In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 132, p. 1141-1150Article in journal (Refereed)
    Abstract [en]

    A series of cobalt-based catalysts have been synthesized using as support γ-Al2O3 promoted by ceria/zirconia mixed oxides with a variable Ce/Zr molar ratio. The obtained catalysts demonstrated oxide promotion results in the protection of the major textural properties, especially for Zr-rich solids. Reducibility of cobalt species was enhanced by the presence of mixed oxides. The chemical composition of the oxide promoter influenced not only physicochemical properties of final catalysts but also determined their performance during the reaction. In this sense, Zr-rich systems presented a superior catalytic performance both in total conversion and in selectivity towards long chain hydrocarbons. The observed Zr-promotion effect could be explained by two significant contributions: firstly, the partial inhibition of Co–Al spinel compound formation by the presence of Zr-rich phases which enhances the availability of Co actives site and secondly, Zr-associate acidic sites promote higher hydrocarbons selectivity.

  • 39. Ilieva, L.
    et al.
    Petrova, P.
    Ivanov, I.
    Munteanu, G.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sobczac, J. W.
    Lisowski, W.
    Kaszkur, Z.
    Markov, P.
    Venezia, A. M.
    Tabakova, T.
    Nanosized gold catalysts on Pr-modified ceria for pure hydrogen production via WGS reaction2015In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 157, p. 138-146Article in journal (Refereed)
    Abstract [en]

    The WGS activity of gold catalysts on ceria doped with Pr (5 and 10 at% Pr) was studied. The supports were synthesized by impregnation (IM) and microemulsion (ME) method. Gold (3 wt%) was introduced by deposition-precipitation method. The samples were characterized by means of XRD, TEM, XPS and TPR measurements. The catalytic activity in WGSR of fresh catalysts did not differ significantly. After re-oxidation following the first catalytic run, the activity of gold catalyst on IM support with 5 at% Pr increased, while a significant drop in activity of the gold catalyst on ME support containing 10 at% Pr was registered. In the latter case the presence of very small gold particles were responsible for the initial WGS activity, while their agglomeration after the catalytic reaction caused the observed activity decrease. In the former case the higher activity during the second catalytic run could be explained by: (i) the redox behavior, showing that only in this case the most mobile oxygen could be fully recovered; (ii) the morphology of the support, revealing better crystallization of the support after WGS catalytic test as compared to the presence of partially amorphous ceria in the fresh gold catalyst.

  • 40. Ilieva, L.
    et al.
    Petrova, P.
    Tabakova, T.
    Pantaleo, G.
    Montes, V.
    Sobczak, J. W.
    Lisowski, W.
    Kaszkur, Z.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Venezia, A. M.
    Pure hydrogen production via PROX over gold catalysts supported on Pr-modified ceria2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 134, p. 628-635Article in journal (Refereed)
    Abstract [en]

    Two series of Pr-doped (5 and 10 at.% Pr) cerium oxides were synthesized by impregnation (IM) and microemulsion method (ME). The Au catalysts (3 wt.%) supported on these oxides were tested in PROX. The samples were characterized by XRD, XPS and TPR measurements. At the operating temperature of the fuel cells (80-120 degrees C) gold catalysts on Pr-doped ceria supports synthesized by IM method exhibited much higher PROX activity as compared to the case of ME method. The observed different catalytic behavior was attributed to the different support preparation affecting the gold particle sizes and the mixed support features. In the case of mixed supports synthesized by IM the size of gold particles established by XRD is smaller and the supply of oxygen evidenced by the obtained TPR results is higher as compared to the gold catalysts on the ME prepared mixed supports. The higher gold dispersion as well as the more defective structure assumed by higher microstrain parameter of ceria lattice (XRD data) due to Pr-doping by IM method, improved both the reducibility and the PROX activity up to 120 degrees C.

  • 41. Jang, B. W. L.
    et al.
    Reynolds, J. G.
    Boutonnet, Magali
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Spivey, J. J.
    Catalysis and plasma technology - Preface2002In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 72, no 3-4, p. 171-171Article in journal (Refereed)
  • 42. Laguna, O. H.
    et al.
    Centeno, M. A.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Odriozola, J. A.
    Au-supported on Fe-doped ceria solids prepared in water-in-oil microemulsions: Catalysts for CO oxidation2016In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 278, p. 140-149Article in journal (Refereed)
    Abstract [en]

    Gold catalysts were synthesized by deposition-precipitation employing Fe-doped ceria systems, previously obtained by means of the water-in-oil microemulsions methodology with different iron contents (10, 25 and 50 Fe at.%). The final catalysts were tested in the CO oxidation reaction in presence of H-2. After gold deposition the crystalline structure of the supports was not altered. Moreover no XRD lines associated to gold were detected, indicating its high dispersion. Solid solution was generated in all samples, although the segregation of iron oxide was detected for the material with the highest iron loading. This phenomenon was then enhanced for the corresponding gold catalyst that also presented sintering of the gold nanoparticles. Strong interaction between gold and the oxygen vacancies of the supports was demonstrated, as well as the promotion of the reducibility of surface Ce4+ and Fe3+ species at low temperatures. A remarkable promotion of the CO conversion at lower temperatures respect to that of the supports was observed for the gold catalysts. Below 120 degrees C, lower the amount of iron incorporated, higher the catalytic performance of the catalyst. This behaviour is closely related not only to a high gold dispersion but also to the ability for creating additional oxygen vacancies in the support, required for the CO oxidation reaction.

  • 43. Laguna, O. H.
    et al.
    Centeno, M. A.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Odriozola, J. A.
    Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions2011In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 106, no 3-4, p. 621-629Article in journal (Refereed)
    Abstract [en]

    A series of Ce-Fe mixed oxides as well as the pure oxides were synthesized by the microemulsions method. The solid solution formation was established for all the Fe-doped systems and only a hardly noticeable segregation of alpha-Fe(2)O(3) was appreciated for the solid with the maximum iron content (50 at.% Fe). The oxygen exchange is improved for all the Fe-doped systems; however the 10 at.% Fe appears as the optimal iron content for achieving the maximum oxygen vacancies concentration and the higher reducibility efficiency. The CO oxidation (TOX. PROX) is especially achieved for the solids with the lower iron contents but with a superior oxygen vacancies proportion. These Ce-Fe systems prepared from microemulsions are very attractive to be considered as supports for depositing active phases capable of enhancing oxygen exchange ability of the whole system, allowing higher CO oxidation abilities.

  • 44.
    Lakshmanan, Ramnath
    et al.
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Okoli, Chuka
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology. KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Effect of Magnetic Iron Oxide Nanoparticles for Surface Water Treatment: Trace Minerals and MicrobesManuscript (preprint) (Other academic)
  • 45.
    Lakshmanan, Ramnath
    et al.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Industrial Biotechnology. KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Effect of magnetic iron oxide nanoparticles in surface water treatment: Trace minerals and microbes2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 129, p. 612-615Article in journal (Refereed)
    Abstract [en]

    The existing water treatment process often uses chemicals, which is of high health and environmental concern. The present study focused on the efficiency of microemulsion prepared magnetic iron oxide nanoparticles (ME-MIONs) and protein-functionalized nanoparticles (MOCP. +. ME-MIONs) in water treatment. Their influence on mineral ions and microorganisms present in the surface water from lake Brunnsviken and örlången, Sweden were investigated. Ion analysis of water samples before and after treatment with nanoparticles was performed. Microbial content was analyzed by colony forming units (CFU/ml). The results impart that ME-MIONs could reduce the water turbidity even in low turbid water samples. Reduction of microbial content (98%) was observed at 37 °C and more than 90% reduction was seen at RT and 30 °C when compared to untreated samples from lake örlången. The investigated surface water treatment method with ME-MIONs was not significantly affecting the mineral ion composition, which implies their potential complement in the existing treatment process.

  • 46.
    Lakshmanan, Ramnath
    et al.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Microemulsion prepared magnetic nanoparticles for phosphate removal: Time efficient studies2014In: Journal of Environmental Chemical Engineering, ISSN 2213-3437, Vol. 2, no 1, p. 185-189Article in journal (Refereed)
    Abstract [en]

    The present study investigates the effective removal of phosphate in sewage wastewater using magnetic iron oxide nanoparticles (MION). The microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) of around 7-10 nm was synthesized using water-in-oil microemulsion method. The interaction of ME-MION and phosphate was studied using In situ FT-IR technique. Batch experiments were carried out with wastewater to determine the conc. and time efficiency using ME-MION for removal of phosphate. The vibration peak at 1004 cm-1 and the presence of hydroxyl group (OH-) at 3673 cm-1 confirms the binding of phosphate to ME-MION. ME-MION with 0.44 g L-1 exhibited more than 95% phosphate reduction in 5 min and close to 100% in 20 min. Conversely the experimental data obtained has been fitted with Langmuir isotherm model and also exhibited high correlation coefficients. The ME-MION was regenerated and can be reused for minimum 5 consecutive times. Efficient and fast reduction of phosphate was attained while the recovery of nanoparticles was achieved by an external magnetic field. To the author's knowledge, this is the first report that underscores around 100% phosphate removal from wastewater using ME-MION in 20 min. The approach utilized in this study offers a potential technique in the reduction of phosphate in wastewater whilst, reducing the time and reuse of nanoparticles.

  • 47.
    Lakshmanan, Ramnath
    et al.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Rajaraman, P.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Application of magnetic nanoparticles for wastewater treatment using response surface methodology2013In: Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013: Volume 3, 2013, 2013, p. 690-693Conference paper (Refereed)
    Abstract [en]

    Nanotechnology is considered as one of the key techniques that provide unique materials with high reactivity due to large surface to volume ratio and which could address the fundamental issues in water sector and environment. The present study investigates the efficiency of magnetic iron oxide nanoparticles in wastewater treatment based on Central Composite Face centered (CCF) matrix of response surface methodology for the reduction of turbidity and total nitrogen. The multiple linear regression fit (MLR) obtained for turbidity (r2 0.97) and total nitrogen reduction (r 0.94) supports the future predictions obtaining a significant model. The maximum reduction of turbidity and total nitrogen achieved was 93% and 41% respectively. Other contaminants such as color, total organic carbon, nitrate and microbial content could be reduced. The present study reveals that magnetic property, time and reduction of pollutants by magnetic nanoparticles could impart an efficient treatment process.

  • 48.
    Lakshmanan, Ramnath
    et al.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Rajaraman, Premanand
    Sri Sairam Engineering College, Department of Physics.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Industrial Biotechnology. KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Järås, Sven
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Application of Magnetic Nanoparticles for the removal of turbidity and total nitrogen from sewage wastewater: Modelling studiesManuscript (preprint) (Other academic)
  • 49.
    Lopez, Luis
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology. UMSA Universidad Mayor de San Andrés, Bolivia.
    Montes, V.
    Kušar, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Cabrera, S.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Syngas conversion to ethanol over a mesoporous Cu/MCM-41 catalyst: Effect of K and Fe promoters2016In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 526, p. 77-83Article in journal (Refereed)
    Abstract [en]

    Transportation fuels such as ethanol can be obtained through thermochemical processing of biomass. Interest in the development of more selective catalysts for the conversion of biomass-derived syngas (H2 + CO) to ethanol is increasing in both academia and industry. In this work, we have evaluated the performances of K and Fe as metal promoters of a mesoporous Cu/MCM-41 catalyst and their effects on the product selectivity and especially on ethanol formation. The metal loading was 29 wt.% Cu, 2 wt.% Fe and 1.6 wt.% K. The catalysts were tested at 300 °C, 20 bar and gas-hourly-space-velocities in the range of 1500–30000 mlsyngas/gcat h; under these conditions the syngas conversion level was between 2 and 11%. The non-promoted Cu/MCM-41 catalyst showed interesting selectivity toward oxygenated compounds, mostly methanol. The addition of K as promoter increases the selectivity toward methanol even more, while the addition of Fe as promoter favors the formation of hydrocarbon compounds. When both K and Fe as promoters are incorporated into the Cu/MCM-41 catalyst, the reaction rate to oxygenated compounds is notably increased, especially for ethanol. The space time yield for ethanol for the Cu/MCM-41 catalyst is 0.3 × 10−5 carbon-mol/gcath which increases to 165.5 × 10−5 carbon-mol/gcath for the Cu-Fe-K/MCM-41 catalyst. From XPS analysis, the Cu-Fe-K/MCM-41 catalyst was found to have the following atomic composition: Cu0.34Fe0.08K0.08Si1.00. The promoting effect of both K and Fe, may be related to an increased reaction rate toward CO non-dissociation and CO-dissociation paths, respectively, which is beneficial for the ethanol formation. Further catalytic results, catalyst characterization and discussion of results are presented in this work.

  • 50.
    Lopez Nina, Luis Gagarin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology. UMSA Universidad Mayor de San Andres, Bolivia.
    Velasco, Jorge A.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Cabrera, Saul
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven G.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Effect of syngas conversion and catalyst reduction temperature in the synthesis of ethanol: concentration of water vapor in mesoporous Rh/MCM-41 catalyst2015In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 69, p. 183-187Article in journal (Refereed)
    Abstract [en]

    Rh-based catalysts typically show low selectivity to CO2 in the synthesis of ethanol from syngas. However, a novel mesoporous Rh/MCM-41 catalyst shows high selectivity to CO2 in a large range of syngas conversions; 1% to 68%, regulated by adjusting the operation conditions (270-430 degrees C, 30-90 bar and 6000-40,000 ml(syngas)/gcat h). The same effect is obtained at different catalyst reduction temperatures (200 degrees C and 500 degrees C) as well as on the non-reduced catalyst. A high concentration of water vapor seems to occur in the pores of Rh/MCM-41 which may promote the water-gas-shift-reaction, producing extra CO2 and H-2. (C) 2015 Elsevier B.V. All rights reserved.

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