Influence of the catalyst loading on the activity and the CO selectivity of supported Ru catalysts in the selective methanation of CO in CO₂ containing feed gases

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• 作者：Stephan Eckle^a ; Matthias Augustin^a ; Hans-Georg Anfang^b ; R. Jü ; rgen Behm^a ; ^{juergen.behm@uni-ulm.de}
• 关键词：CO methanation ; CO2 methanation ; Mechanism ; CO adsorption ; Selectivity ; Ru catalyst
• 刊名：Catalysis Today
• 出版年：2012
• 出版时间：12 February 2012
• 年：2012
• 卷：181
• 期：1
• 页码：40-51
• 全文大小：1529 K

文摘

We have investigated the methanation of CO and CO₂ over Ru/zeolite catalysts with different Ru loading in semi-realistic reformate gases by in situ X-ray absorption spectroscopy (XAS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and kinetic measurements. Increasing the Ru loading causes an increase of the mean particle size from 0.9 nm (2.2 wt. % Ru) to 1.9 nm (5.6 wt. % Ru). At the same time, also the activity for CO methanation increases, while the selectivity for CO methanation, which is constant at 100 % for reformate gases with 0.6 % CO, decreases at low CO contents. The latter findings are interpreted in terms of a change in the physical effects governing the selectivity for CO methanation with increasing Ru particle size, from an inherently low activity for CO₂ dissociation and subsequent CO_ad methanation on very small Ru nanoparticles to a site blocking mechanism on larger Ru nanoparticles. In the latter mechanism, CO₂ methanation is hindered by a reaction inhibiting adlayer of CO at higher CO_ad coverages, i.e., at not too low CO concentrations, but facile in the absence of a CO adlayer, at lower CO concentrations in the reaction gas mixture.