Ni/Ce0.9Eu0.1O1.95 with enhanced coke resistance for dry reforming of methane

Abstract

Methane reforming with carbon dioxide provides an environmentally friendly route for converting methane to synthesis gas while consuming two greenhouse gases. Large-scale implementation of this process has been stalled by the lack of stable catalysts owing to the rapid deactivation caused by carbon deposition and sintering. Ni/Ce0.9Eu0.1O1.95 catalysts with better activity and enhanced stability are synthesized for dry reforming of methane. This reaction is believed to occur via the direct C-H bond dissociation of CH4 to form surface carbon intermediates on metal sites followed by the oxidation of carbon intermediates to CO. Compared with CeO2, Ce0.9Eu0.1O1.95 with stronger lattice oxygen mobility and higher oxygen storage capacity generates more mobile active oxygen species that participate in eliminating the carbon deposition. Moreover, the particle size of Ni species decreases and Ni shifts to higher oxidation state as a result of the strong metal-support interaction over Ce0.9Eu0.1O1.95. The more surface oxygen species are involved in the reaction, the more methane can be converted to CO rather than surface carbon. As a consequence, the balance between the rate of carbon generation (i.e., the direct C-H bond dissociation of CH4) and the rate of carbon consumption (i.e., the oxidation of formed carbon intermediates) can be achieved for dry reforming of methane over Ni/Ce0.9Eu0.1O1.95, leading to less coke accumulation and thereafter an improved overall catalytic performance.