Toward Understanding and Simplifying the Reaction Network of Ketene Production on ZnCr₂O₄ Spinel Catalysts

It was found experimentally that a reduced ZnCr 2 O 4 spinel performs well in syngas conversion to ketene (CH 2 CO), which is a key intermediate for ethylene production. In this work, we have systematically investigated the stability of several ZnCr 2 O 4 spinel surfaces by using first-principles calculations. It was identified via microkinetic modeling that the partially reduced ZnCr 2 O 4 (111) surface is preferable to produce ketene. According to the microkinetic modeling, the key of ketene production is the coupling between CH 2 * and CO*. However, half of the reactive sites were covered by CH 3 CO* at a steady state, which is formed through the coupling of CH 3 * and CO*, while it is hard to dehydrogenate to CH 2 CO. Finally, we propose a global optimization algorithm for ranking the importance of elementary reactions and pathways, which can be considered as a useful tool for simplifying the reaction network and rational design of catalysts in the future.