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Deactivation of supported nickel catalysts during CO methanation
KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.ORCID-id: 0000-0003-3826-1858
KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
2014 (engelsk)Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 486, s. 143-149Artikkel i tidsskrift (Fagfellevurdert) Published
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.

sted, utgiver, år, opplag, sider
2014. Vol. 486, s. 143-149
Emneord [en]
Methanation, Deactivation, Support, Titania, Carbon formation
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-157220DOI: 10.1016/j.apcata.2014.08.021ISI: 000344439400016Scopus ID: 2-s2.0-84908648449OAI: oai:DiVA.org:kth-157220DiVA, id: diva2:769767
Forskningsfinansiär
EU, FP7, Seventh Framework Programme, 308733Swedish Energy Agency
Merknad

QC 20141209

Tilgjengelig fra: 2014-12-09 Laget: 2014-12-08 Sist oppdatert: 2017-12-05bibliografisk kontrollert
Inngår i avhandling
1. Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation
Åpne denne publikasjonen i ny fane eller vindu >>Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation
2016 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

            A potential route for converting different carbon sources (coal, natural gas and biomass) into synthetic fuels is the transformation of these raw materials into synthesis gas (CO and H2), followed by a catalytic step which converts this gas into the desired fuels. The present thesis has focused on two catalytic steps: Fischer-Tropsch synthesis (FTS) and methanation. The Fischer-Tropsch synthesis serves to convert synthesis gas into liquid hydrocarbon-based fuels. Methanation serves instead to produce synthetic natural gas (SNG). Cobalt catalysts have been used in FTS while nickel catalysts have been used in methanation.

            The catalyst lifetime is a parameter of critical importance both in FTS and methanation. The aim of this thesis was to investigate the deactivation causes of the cobalt and nickel catalysts in their respective reactions.

            The resistance to carbonyl-induced sintering of nickel catalysts supported on different carriers (γ-Al2O3, SiO2, TiO2 and α-Al2O3) was studied. TiO2-supported nickel catalysts exhibited lower sintering rates than the other catalysts. The effect of the catalyst pellet size was also evaluated on γ-Al2O3-supported nickel catalysts. The use of large catalyst pellets gave considerably lower sintering rates. The resistance to carbon formation on the above-mentioned supported nickel catalysts was also evaluated. Once again, TiO2-supported nickel catalysts exhibited the lowest carbon formation rates. Finally, the effect of operating conditions on carbon formation and deactivation was studied using Ni/TiO2 catalysts. The use of higher H2/CO ratios and higher pressures reduced the carbon formation rate. Increasing the temperature from 280 °C to 340 °C favored carbon deposition. The addition of steam also reduced the carbon formation rate but accelerated catalyst deactivation.

            The decline in activity of cobalt catalysts with increasing sulfur concentration was also assessed by ex situ poisoning of a cobalt catalyst. A deactivation model was proposed to predict the decline in activity as function of the sulfur coverage and the sulfur-to-cobalt active site ratio. The results also indicate that sulfur decreases the selectivity to long-chain hydrocarbons and olefins.

sted, utgiver, år, opplag, sider
Stockholm: US-AB, 2016. s. xii, 124
Serie
TRITA-CHE-Report, ISSN 1654-1081
Emneord
cobalt, nickel, Fischer-Tropsch synthesis, methanation, deactivation, carbonyl, sintering, carbon fomation. sulfur, poisoning
HSV kategori
Forskningsprogram
Kemiteknik
Identifikatorer
urn:nbn:se:kth:diva-190593 (URN)978-91-7729-060-5 (ISBN)
Disputas
2016-09-23, F3, Lindstedtsvägen 26, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Forskningsfinansiär
EU, FP7, Seventh Framework Programme, 308733
Merknad

QC 20160817

Tilgjengelig fra: 2016-08-17 Laget: 2016-08-12 Sist oppdatert: 2016-08-18bibliografisk kontrollert

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