Influence of Reaction Conditions on Pathways of Methane and Carbon Dioxide Reforming over NiMo2C Catalyst
The catalytic pathways of Ni/Mo2C in methane and carbon dioxide reforming reaction involve both noble metal mechanism and oxidation-carburization cycle,with the latter usually being the predominant pathway at higher temperatures,attracting significant attention.Reaction conditions exert significant influence on the oxidation-carburization cycle mechanism.Two cyclic pathways can be obtained by varying the reactant gas composition and space velocity:(Ⅰ)Mo2C→MoO2→Mo2C,wherein Mo2C is initially oxidized to MoO2 by CO2,followed by the carbonization of MoO2 by CH4 to regenerate Mo2C;(Ⅱ)Mo2C→MoO2→Mo→Mo2C,wherein Mo2C is first oxidized to MoO2 by carbon dioxide,then MoO2 undergoes reduction with the H species dissociated from CH4 to produce metallic Mo and H2O,subsequently,metallic Mo interacts with the carbon species dissociated from methane to form Mo2C.The cyclic pathways have a significant impact on catalyst stability,with cycle Ⅱ being more favorable for catalyst stability.
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