Ethanol Reaction on Co3O4(110) and Co(0001): A Microkinetic Model Analysis
2016
Li, Meng-Ru | Wang, Gui-Chang
In the present work, the microkinetic model analysis is performed to study the reaction mechanisms and catalytic activity of ethanol reactions over Co⁰, Co²⁺, and Co³⁺ sites. On the Co⁰ site, it has been reported that the mechanism of ethanol reaction is CH₃CH₂OH → CH₃CH₂O → CH₃CHO → CH₃CO → CH₃ + CO, and the final products are CO and H₂. H₂ is formed by the combination of adsorbed H species. The microkinetic simulation shows that the elementary steps of the dehydrogenation of CH₃CH₂O species into CH₃CHO, C–C cleavage in CH₃CO, and desorption of CO dominate the rate of CO formation as the rate-controlling steps. The elementary steps of desorption of CH₃CHO and the C–C cleavage in CH₃CO species have the main impact on the selectivity as the selectivity-controlling steps. On the Co²⁺ site, the mechanism was reported to be CH₃CH₂OH → CH₃CH₂O → CH₃CHO, and the main final product is CH₃CHO. The microkinetic simulation demonstrates that the rate-controlling step is desorption of CH₃CHO. The selectivity-controlling steps are desorption of CH₃CHO and the dehydrogenation in CH₃CHO. On the Co³⁺ site, the mechanism has been examined, CH₃CH₂OH → CH₃CH₂O → CH₃CHO→ CH₂CHO→ CH₂CO → CHCO → CCO → COCO → CO → CO₂, and the final products are CO₂ and H₂O. The corresponding rate-controlling step and selectivity-controlling step on the Co³⁺ site is the step of dehydrogenation in CH₃CH₂O species into CH₃CHO species. The present result may help people to modify the experiment condition as the pressure, temperature, and catalyst to get the target product as CH₃CHO, CO, and CO₂ with high selectivity and reactivity.
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