Ni–MgO–CeO2 Catalysts for Reforming of Mixed Alkanes: Structure‐Performance Relationship and Reaction Networks

Ni–MgO–CeO₂ catalysts were prepared for reforming of mixed alkane, which is an effective way to utilize the CH₄ and C₂H₆ in the purge gas of C1 chemistry. Mg-rich support with small and highly-dispersed Ni particles can achieve a high C₂H₆ conversion, whereas Ce-rich support with better oxygen mobility can reach a balance between C _x H _y generation and conversion, resulting in a consistent coke-free conversion in a 100-h reaction.

Abstract

Purge gas that is by-produced during syngas conversion contains significant amounts of low carbon alkanes (CH₄ and C₂H₆ in particular), and their flare and release represent one of the major sources of CO₂ emission for C1 chemistry. In this context, reforming of the mixed alkanes (RMA) in the purge gas and recycling of the produced syngas can effectively enhance the carbon and hydrogen efficiency of C1 chemistry. However, in-depth structure-performance relationships and catalytic mechanisms were rarely investigated for RMA, which forms a major research gap for further development. Herein, a series of Ni–MgO–CeO₂ catalysts with different Mg and Ce contents were prepared, and the catalytic performance in reforming of mixed alkanes was investigated. It was found that smaller Ni particles on the Mg-rich samples (NM₆C₀ and NM₅C₁) are more effective for the activation of C₂H₆. However, the generated C _x H _y intermediates cannot be converted with matching kinetics, which resulted in the formation of unwanted CH₄ and more importantly, larger amounts of carbon deposition. On the other hand, despite a moderate C₂H₆ conversion is observed on Ce-rich samples, appropriate balance between the generation of C _x H _y intermediates from alkanes and their conversion aided by the activated CO₂ and H₂O can be established, resulting in excellent anticarbon properties. Overall, the optimum catalyst (NM₃C₃) showed stable CH₄ and C₂H₆ conversion (28% and 43%, respectively) and negligible carbon formation in 100-h operation. Upon the comparison with individual reforming of CH₄ and C₂H₆, this study also presented in-depth understanding on the different mechanism and reaction network for reforming of mixed alkanes, which solidifies the foundation of catalyst design in related areas including CO₂ utilization or C1 reforming.

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