Ni-Mn catalysts on silica-modified alumina for CO2 methanation

Wilbert L. Vrijburg, G. Garbarino, Wei Chen, Alexander Parastaev, Alessandro Longo, Evgeny A. Pidko, Emiel J.M. Hensen (Corresponding author)

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Abstract

The viability of the Power-to-Gas (PtG) concept is strongly dependent on the development of highly active and stable methanation catalysts obtained from cheap and abundant elements. In this paper, the promotional effect of MnO on Ni catalysts supported on silica-modified γ-Al2O3 (SA) was investigated in CO2 and CO methanation on catalysts with Mn/Ni atomic ratios between 0 and 0.25. Significantly higher methanation rates and CH4 selectivities were obtained for Mn-promoted compositions compared to Ni-only catalysts. The optimal NiMn/SA (Mn/Ni = 0.25) catalyst exhibited improved stability compared with unpromoted Ni/SA at 20 bar. The nature of the catalyst precursor and active catalyst was studied with STEM-EDX, XPS, and X-ray absorption spectroscopy (XAS). Evidence of a mixed Ni-Mn oxide in the catalyst precursor was obtained by EXAFS. EXAFS measurements revealed that the reduced catalyst consisted of metallic Ni particles and small oxidic Mn2+ species. Moreover, Mn addition improved the Ni dispersion and enhanced the Ni2+ reducibility by weakening the interaction between the Ni-oxide precursor and the support. A mechanistic study involving IR spectroscopy and steady-state isotopic (13CO2) transient kinetic analysis (SSITKA) showed that the presence of Mn enhanced CO2 adsorption and activation.
Original languageEnglish
Pages (from-to)358-371
Number of pages14
JournalJournal of Catalysis
Volume382
DOIs
Publication statusPublished - 1 Feb 2020

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Keywords

  • CO valorization
  • Manganese promotion
  • Methanation
  • Nickel
  • Power-to-gas

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