Micro- and mesoporous supports for CO2 methanation catalysts : a comparison between SBA-15, MCM-41 and USY zeolite

Bacariza, M.C. and Graça, I. and Bebiano, S.S. and Lopes, J. M. and Henriques, C. (2018) Micro- and mesoporous supports for CO2 methanation catalysts : a comparison between SBA-15, MCM-41 and USY zeolite. Chemical Engineering Science, 175. pp. 72-83. ISSN 0009-2509

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    Abstract

    Mesoporous SBA-15 synthesized by two different methods and MCM-41 were used as supports for Ni and Ni-Ce catalysts applied in CO2 methanation reaction. The performances obtained for both materials were compared taking into account the differences in terms of textural properties, Ni species and reaction mechanism. Results were compared with the reported in the literature for a microporous USY zeolite. XRD, DRS UV–Vis, H2-TPR and TEM were used for the characterization of the samples. Catalytic tests were performed under the same conditions for all catalysts. Finally, FTIR Operando studies were carried out in order to establish differences from the mechanistically point of view as well as in terms of CO2 adsorption species for the different samples. Promising data was obtained with the Ni-based SBA-15 catalysts whatever the preparation method. Despite the greater Ni particles size, MCM-41 also reported interesting catalytic performances, so that presenting the highest TOF values among the catalysts studied. The good results obtained for the MCM-41 could be explained by the lower amount of non-reactive carbonyl species adsorbed on the Ni0 particles surface during the reaction as well as by the enhanced interaction between metal and support reflected in the calculated band gap values. All the results are comparable to the obtained using a HNaUSY zeolite with Si/Al = 2.8 as support. Cerium incorporation on Ni/mesoporous supports allowed enhancing the CO2 conversion, especially at lower temperatures, as already reported for the zeolite-based samples.