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Publications (10 of 14) Show all publications
Haghighi Moud, P., Andersson, K. J., Lanza, R. & Engvall, K. (2016). Equilibrium potassium coverage and its effect on a Ni tar reforming catalyst in alkali- and sulfur-laden biomass gasification gases. Applied Catalysis B: Environmental, 190, 137-146
Open this publication in new window or tab >>Equilibrium potassium coverage and its effect on a Ni tar reforming catalyst in alkali- and sulfur-laden biomass gasification gases
2016 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 190, p. 137-146Article in journal (Refereed) Published
Abstract [en]

Biomass conversion to syngas via gasification produces certain levels of gaseous by-products, such as tar and inorganic impurities (sulfur, potassium, phosphorus etc.). Nickel, a commonly used catalyst for hydrocarbqn steam reforming, suffers reduced reforming activity by small amounts of sulfur (S) or potassium (K), while resistance against deleterious carbon whisker formation increases. Nevertheless, the combined effect of biomass derived gas phase alkali at varying concentrations together with sulfur on tar reforming catalyst performance under realistic steady-state conditions is largely unknown. Prior to this study, a methodology to monitor these effects by precise K dosing as well as K co-dosing with S was successfully developed. A setup consisting of a 5 kW biomass fed atmospheric bubbling fluidized bed gasifier, a high temperature hot gas ceramic filter, and a catalytic reactor operating at 800 degrees C were used in the experiments. Within the current study, two test periods were conducted, including 30 h with 1 ppmv potassium chloride (KCl) dosing followed by 6 h without KCl dosing. Besides an essentially carbon-free operation, it can be concluded that although K, above a certain threshold surface concentration, is known to block active Ni sites and decrease activity in traditional steam reforming, it appears to lower the surface S coverage (theta(s)) at active Ni sites. This reduction in theta(s) increases the conversion of methane and aromatics in tar reforming application, which is most likely related to K-induced softening of the S-Ni bond. The K-modified support surface may also contribute to the significant increase in reactivity towards tar molecules. In addition, previously unknown relevant concentrations of K during realistic operating conditions on typical Ni-based reforming catalysts are extrapolated to lie below 100 mu K/m(2), a conclusion based on the 10-40 mu K/m(2) equilibrium coverages observed for the Ni/MgAl2O4 catalyst in the present study.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Tar reforming, Biomass gasification, Ni-based catalyst, Potassium, Sulfur
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-187323 (URN)10.1016/j.apcatb.2016.03.007 (DOI)000374604900013 ()2-s2.0-84960464172 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20160520

Available from: 2016-05-20 Created: 2016-05-20 Last updated: 2017-11-30Bibliographically approved
Bernardini, A., Gemo, N., Biasi, P., Canu, P., Mikkola, J. P., Salmi, T. & Lanza, R. (2015). Direct synthesis of H2O2 over Pd supported on rare earths promoted zirconia. Catalysis Today, 256, 294-301
Open this publication in new window or tab >>Direct synthesis of H2O2 over Pd supported on rare earths promoted zirconia
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2015 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 256, p. 294-301Article in journal (Refereed) Published
Abstract [en]

In this work Pd (0.3 or 0.6 wt.%) was supported on both ZrxM1-xO2 (M = La, Y, Ce) and on mechanical mixtures of CeO2 and ZrO2. The synthesized catalysts were characterized by XRD, TPR, AAS and CO chemisorption and tested for the direct synthesis of hydrogen peroxide in a high pressure semibatch apparatus. The reactants conversion was limited in order to avoid mass-transfer limitations. No selectivity enhancers of any kind were used and the all the materials were halide free. Small metal particles were obtained (1-2.6 nm). Supports with smaller pore diameters leaded to larger Pd particles, which in turn were found to preferentially support the formation of the peroxide. Moreover, supports with higher reducibility favored the production of H2O2, probably due to an easier reduction of the active metal, essential to achieve high selectivity. Notwithstanding the absence of enhancers, the specific activity and selectivity recorded were very high.

Keywords
Palladium, H2O2 direct synthesis, Zirconia, Ceria, Rare earths
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-173955 (URN)10.1016/j.cattod.2014.12.033 (DOI)000360657000010 ()2-s2.0-85002910325 (Scopus ID)
Funder
The Kempe Foundations
Note

QC 20151006

Available from: 2015-10-06 Created: 2015-09-24 Last updated: 2020-03-10Bibliographically approved
Moud, P. H., Andersson, K. J., Lanza, R., Pettersson, J. B. & Engvall, K. (2015). Effect of gas phase alkali species on tar reforming catalyst performance: Initial characterization and method development. Fuel, 154, 95-106
Open this publication in new window or tab >>Effect of gas phase alkali species on tar reforming catalyst performance: Initial characterization and method development
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2015 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 154, p. 95-106Article in journal (Refereed) Published
Abstract [en]

In thermochemical conversion of biomass to synthesis gas and biofuels, the effect of varying gas phase alkali concentrations on tar reforming catalyst performance in combination with gas phase sulfur and chlorine is largely unknown. The current study demonstrates a new methodology for investigating gas phase alkali adsorption and presents results for early stage adsorption on a Ni-based catalyst under realistic industrial conditions. The experiments were carried out using pine pellets as feedstock in a setup consisting of a 5 kW atmospheric bubbling fluidized bed gasifier, a high temperature hot gas filter and a catalytic reactor - all operating at 850 °C. A potassium chloride solution was atomized with an aerosol generator, and the produced submicrometer KCl particles were continuously introduced to the catalytic reactor where they rapidly evaporated to form KCl (g). The accurate dosing of gas-phase alkali was combined with elimination of transient effects in catalytic performance due to catalyst sintering and S adsorption, and results for K uptake in relation to sulfur uptake were obtained. Different KCl levels in the gas phase demonstrates different initial uptake of K on the catalyst surface, which at low K coverage (θK) is approximately linearly proportional to time on stream. The results also show a clear suppressing effect of sulfur adsorption on potassium uptake. Indications of a slow approach to K equilibration on the catalyst were observed. The potential of the developed methodology for detailed studies under close to industrial conditions is discussed.

Keywords
Alkali, Biomass gasification, Ni catalyst, Potassium, Sulfur, Tar reforming, Adsorption, Catalysts, Chlorine compounds, Fluidization, Fluidized beds, Gasification, Nickel, Sintering, Tar, Bubbling fluidized bed, Linearly proportional, Ni catalysts, Potassium chloride solutions, Thermochemical Conversion, Gases
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-167687 (URN)10.1016/j.fuel.2015.03.027 (DOI)000353893200012 ()2-s2.0-84926632320 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20150602

Available from: 2015-06-02 Created: 2015-05-22 Last updated: 2017-12-04Bibliographically approved
Scarabello, A., Dalle Nogare, D., Canu, P. & Lanza, R. (2015). Partial oxidation of methane on Rh/ZrO2 and Rh/Ce-ZrO2 on monoliths: Catalyst restructuring at reaction conditions. Applied Catalysis B: Environmental, 174-175, 308-322
Open this publication in new window or tab >>Partial oxidation of methane on Rh/ZrO2 and Rh/Ce-ZrO2 on monoliths: Catalyst restructuring at reaction conditions
2015 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 174-175, p. 308-322Article in journal (Refereed) Published
Abstract [en]

0.5% Rh catalysts on ZrO2 or CeO2-ZrO2, coated on monoliths were tested for partial oxidation of methane, (GHSV=100000h-1). We ran temperature cycles up to 850°C, varying the O2/CH4 ratio from 0.5 to 0.7. The catalysts were characterized by XRD, TPR/TPO, BET and chemisorption. ZrO2 required a long conditioning step, to reach stable performance, while the CeO2-ZrO2 catalyst quickly gained steady activity. The conditioning step is explained with a restructuring of the surface, with the metallic particles becoming smaller. Ceria lowers the ignition temperature by 60°C. At low temperature, ceria allows an increase in CH4 conversion and selectivity to syngas. At high temperature, the CeO2-ZrO2 catalyst significantly increases the CH4 conversion, compared to ZrO2, approaching 100%. However, the selectivity to syngas decreases below 80%. The syngas selectivity is higher at lower O2/CH4 ratio, at any temperature, but the absolute amount of syngas can be larger with more O2.

Keywords
Ceria-zirconia, Methane, Reconstruction, Rhodium, TPR-TPO, Catalysts, Image reconstruction, Synthesis gas, Temperature, Zirconia, Zirconium alloys, Catalyst restructuring, Ignition temperatures, Partial oxidation of methane, Reaction conditions, Stable performance, Temperature cycles, Catalyst activity
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-167686 (URN)10.1016/j.apcatb.2015.03.012 (DOI)000354505100031 ()2-s2.0-84924944067 (Scopus ID)
Note

QC 20150608

Available from: 2015-06-02 Created: 2015-05-22 Last updated: 2017-12-04Bibliographically approved
Lanza, R., Bersani, M., Conte, L., Martucci, A., Canu, P., Guglielmi, M., . . . Rosei, R. (2014). Effect of Crystalline Phase and Composition on the Catalytic Properties of PdSn Bimetallic Nanoparticles in the PROX Reaction. The Journal of Physical Chemistry C, 118(44), 25392-25402
Open this publication in new window or tab >>Effect of Crystalline Phase and Composition on the Catalytic Properties of PdSn Bimetallic Nanoparticles in the PROX Reaction
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2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 44, p. 25392-25402Article in journal (Refereed) Published
Abstract [en]

We present a synthetic strategy for the preparation of palladiumtin alloy and intermetallic nanoparticles. Complexes of palladium(II) and tin(IV) precursors in oleylamine were thermally decomposed in an organic solution in the presence of reducing moieties, leading to the formation of monodispersed nanoparticles with varying crystallographic structures. We found that the nanoparticles crystalline structure closely follows the bulk material phase diagram. The nanoparticles were supported on Al2O3 and their reactivity tested as catalysts for the preferential oxidation of CO in excess of hydrogen (PROX). Different Pd/Sn and O-2/CO ratios have been investigated, and the structurereactivity correlation highlighted. With increasing tin content, the CO ignition temperature remarkably lowers and the CO conversion rate increases, up to the formation of intermetallic phases that concurrently determine a reduction in the catalyst activity; the selectivity of the pure palladium references is preserved.

Keywords
Bimetallic nanoparticles, Catalytic properties, Crystalline phase, PROX reaction
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-157596 (URN)10.1021/jp503531b (DOI)000344579300011 ()2-s2.0-84949146717 (Scopus ID)
Note

QC 20141212

Available from: 2014-12-12 Created: 2014-12-11 Last updated: 2017-12-05Bibliographically approved
Karatzas, X., Jansson, K., Dawody, J., Lanza, R. & Pettersson, L. J. (2011). Microemulsion and incipient wetness prepared Rh-based catalyst for diesel reforming. Catalysis Today, 175(1), 515-523
Open this publication in new window or tab >>Microemulsion and incipient wetness prepared Rh-based catalyst for diesel reforming
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2011 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 175, no 1, p. 515-523Article in journal (Refereed) Published
Abstract [en]

The role of the catalyst preparation technique was investigated for diesel reforming. Reverse microemulsion (ME) and incipient wetness (IW) techniques were used for the preparation of Rh-based monolithic catalysts that were employed for hydrogen generation of low-sulfur diesel via autothermal reforming (ATR). The washcoat of the tested catalysts consisted of 0.5 wt% Rh, 1 wt% Rh, and 1: 1 wt% Rh: Pt supported on gamma-alumina. All washcoats were deposited on 400 cpsi cordierite monoliths. The reaction condition was T(feed) = 650 degrees C, H(2)O/C similar to 2.5, O(2)/C similar to 0.49, TOS = 3 h, GHSV similar to 13 000 h(-1) and P = 1 atm. Fresh and aged powder samples of the catalyst were characterized by N(2)-BET, H(2) chemisorption, XRD, H(2)-TPR, O(2)-TPO and TEM. The activity results established that Rh and RhPt formulations, prepared by ME and IW, are highly active for ATR of diesel where fuel conversions above 92% were obtained. FTIR and NDIR analysis also showed that the highest formation of ethylene was found in the product gas stream from the bimetallic samples indicating that RhPt/Al(2)O(3) is less resistant towards carbon deposition. The latter observation was confirmed by O(2)-TPO analysis of the aged samples where high loads of coke were found both on the active metals and on the support. Interestingly, these effects were less significant on the ME samples. The characterization results clearly showed differences in morphology between the ME and the IW samples. N(2)-BET analysis showed that higher surface area, similar to 268-285 m(2)/g, was obtained with the ME samples. Also, H(2) chemisorption analysis showed that the rhodium dispersion was similar to 10% higher for the ME samples (H/Rh similar to 60-66%). XRD analysis showed that crystalline phases of gamma-alumina were present on all samples. The diffractograms also showed small traces of metallic Pt (similar to 16-30 nm) in the bimetallic samples. H(2)-TPR analysis, showed peaks ascribed to bulk rhodium oxides and rhodium aluminates. It was also noted that the addition of Pt on the support lowered the reducibility of the different rhodium species. TEM analysis performed on the fresh and aged ME and IW bimetallic samples showed mainly Rh(x)Pt(1-x) alloys with an average particle size of similar to 20-50 nm were present on the alumina support. Also, for the aged samples, no sintering effects were noted. Furthermore, rhodium was found to switch oxidation state from e. g. Rh(3+) to Rh(0) while Pt remained in the metallic state.

Keywords
Autothermal reforming, Diesel, Incipient wetness, Platinum, Reverse microemulsion, Rhodium
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-32504 (URN)10.1016/j.cattod.2011.02.042 (DOI)000295735400072 ()2-s2.0-80054860735 (Scopus ID)
Note
QC 20110415Available from: 2011-04-15 Created: 2011-04-15 Last updated: 2017-12-11Bibliographically approved
Lanza, R., Velasco, J. & Järås, S. (2011). Recent developments and achievements in partial oxidation of methane with and without addition of steam (23ed.). In: James J. Spivey (Ed.), Catalysis (pp. 50-95). Royal Society of Chemistry
Open this publication in new window or tab >>Recent developments and achievements in partial oxidation of methane with and without addition of steam
2011 (English)In: Catalysis / [ed] James J. Spivey, Royal Society of Chemistry, 2011, 23, p. 50-95Chapter in book (Refereed)
Abstract [en]

The latest works on catalytic partial oxidation of methane (CPO) have beenconsidered and reviewed to give an updated frame of the state of the art inthis topic. Papers published since 2008 have been considered, dealing withthe process both without and with addition of steam. Particular attentionwas dedicated to Ni and Rh, that are the most used metals. The mechanismfollowed by the reaction was also considered as well as new and promisingtechnologies such as SOFCs, membrane reactors and plasma systems.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2011 Edition: 23
Series
Catalysis
Keywords
CPO, steam, syngas, ATR, methane, H2
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-88872 (URN)10.1039/9781849732772-00050 (DOI)2-s2.0-84860250151 (Scopus ID)978-1-84973-277-2 (ISBN)
Note
QC 20120222Available from: 2012-02-14 Created: 2012-02-14 Last updated: 2015-11-04Bibliographically approved
Lanza, R., Canu, P. & Järås, S. G. (2010). Methane partial oxidation over Pt-Ru catalyst: An investigation on the mechanism. Applied Catalysis A: General, 375(1), 92-100
Open this publication in new window or tab >>Methane partial oxidation over Pt-Ru catalyst: An investigation on the mechanism
2010 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 375, no 1, p. 92-100Article in journal (Refereed) Published
Abstract [en]

The mechanism of the partial oxidation of methane has been investigated over a bimetallic Pt-Ru catalyst. Dedicated experiments aimed to separate and quantify the relative contribution of single reactions included in the so-called "combustion and reforming" mechanism using the same catalyst. The catalyst is 0.5% Ru and 0.5% Pt (w/w) supported on mixture of alumina, ceria and zirconia (75/4.4/20.6%, w/w), washcoated on a ceramic monolith. Steam reforming, dry reforming, direct and reverse water-gas shift reactions were investigated. The temperature range investigated is 300 < T < 800 degrees C, while the space velocity range is 25.000 < GHSV < 100.000 h(-1). Conditions at which single side reactions are expected to occur during the partial oxidation process, were approximated by tuning the reactant composition. The experimental results are also compared with thermodynamic equilibrium calculations. The CO and H-2 yields of partial oxidation have been quantitatively connected with steam and dry reforming, while the persistent water-gas shift reaction always rearranges the products and intermediates.

Keywords
Partial oxidation, Methane, Syngas, Mechanism, synthesis gas, ruthenium catalysts, syngas production, monoliths, rh
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-19278 (URN)10.1016/j.apcata.2009.12.021 (DOI)000275144200012 ()2-s2.0-74849102042 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
Lanza, R., Canu, P. & Dalle Nogare, D. (2009). Gas Phase Chemistry in Cellulose Fast Pyrolysis. Industrial & Engineering Chemistry Research, 48(3), 1391-1399
Open this publication in new window or tab >>Gas Phase Chemistry in Cellulose Fast Pyrolysis
2009 (English)In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 48, no 3, p. 1391-1399Article in journal (Refereed) Published
Abstract [en]

We experimentally and theoretically studied cellulose pyrolysis at high temperature and short residence time. We investigated the gas phase chemistry with dedicated experiments and feeding intermediates. Results have been also compared with equilibrium calculations, both single (gas) phase and allowing for solid C formation. Our aim was to understand the cellulose degradation mechanism and particularly the role of gas phase chemistry. We provided evidence of a simplified mechanism, where CO formation is a first, fast step that can be related to levoglucosan ring opening, while H(2) comes from a totally different route, based on hydrocarbon reforming reactions, which also provide further CO. In addition, butadiene was identified as a key intermediate in the decomposition sequence. The different paths and rates of CO formation and H2 formation explain why the ratio of CO to H(2) is not constant, particularly at short residence time. A two-stage process or longer contact time is required, if aiming at syngas production.

Keywords
Cellulose mechanism pyrolysis
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-88669 (URN)10.1021/ie801280g (DOI)000262892800046 ()2-s2.0-61549129223 (Scopus ID)
Note

QC 20120220

Available from: 2012-02-14 Created: 2012-02-14 Last updated: 2020-05-11Bibliographically approved
Lanza, R., Eriksson, E. & Pettersson, L. J. (2009). NOx selective catalytic reduction over supported metallic catalysts. Catalysis Today, 147, S279-S284
Open this publication in new window or tab >>NOx selective catalytic reduction over supported metallic catalysts
2009 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 147, p. S279-S284Article in journal (Refereed) Published
Abstract [en]

In this work we present the results obtained with 3 catalysts (Pt, Rh and Ag on alumina) tested in ranges of temperatures and gas hourly space velocities typical of diesel engines in real trucks. NO concentration was 500 ppm, C3H6 ranged between 500 and 2000 ppm, while oxygen was always 5%. All the catalysts were active and showed high conversions. Both Pt and Rh were active at low temperature (T-50 = 200-250 degrees C) but had quite high selectivity towards NO2. Silver was active at higher temperature, but showed very high selectivity towards N-2. A strong boosting effect on NO conversion was recorded if H-2 was added to the gas mixture.

Keywords
HC-SCR, DeNO(x), Alumina, H-2 effect, Steam
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-30687 (URN)10.1016/j.cattod.2009.07.045 (DOI)000269990800046 ()2-s2.0-69249222494 (Scopus ID)
Note

QC 20110310 3rd International Conference on Structured Catalysts and Reactors (ICOSCAR-3), Ischia, ITALY, SEP 27-30, 2009

Available from: 2011-03-10 Created: 2011-03-04 Last updated: 2017-12-11Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-9391-7552

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