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Understanding the Product Selectivity of Syngas Conversion on ZnO Surfaces with Complex Reaction Network and Structural Evolution
ACS Catalysis ( IF 12.9 ) Pub Date : 2021-09-17 , DOI: 10.1021/acscatal.1c02111
Xiaoyan Fu 1, 2, 3 , Jiayi Li 3 , Jun Long 1, 2, 3 , Chenxi Guo 3 , Jianping Xiao 3, 4
Affiliation  

Recently, a bifunctional oxide–zeolite (OX-ZEO) catalyst was widely studied experimentally, which can selectively convert syngas to light olefins. The performance of OX-ZEO is exceptional, while the mechanism is controversial. In this work, we have first developed an algorithm based on graph theory to establish a complete reaction network for syngas conversion to methanol, ketene, and methane. Combined with density functional theory (DFT) calculations, the activity and selectivity of syngas conversion over zinc oxide (ZnO) are systematically studied by a reaction phase diagram. The key intermediate, ketene, is observed in experiments, which has been first confirmed theoretically in this work. The evolution of ZnO surfaces is found to be a key factor of diverse product selectivity. It is found that methanol production is more favored over the ZnO surfaces with a low oxygen vacancy concentration. As the oxygen vacancy increases, the main product evolves gradually from methanol to ketene and finally to methane. Accordingly, the overall reaction activity increases too. Our prediction from the reaction phase diagram is finally verified by microkinetic modeling.

中文翻译:

了解具有复杂反应网络和结构演化的 ZnO 表面合成气转化的产物选择性

最近,对一种双功能氧化物-沸石(OX-ZEO)催化剂进行了广泛的实验研究,该催化剂可以选择性地将合成气转化为轻质烯烃。OX-ZEO 的性能非常出色,但其机制存在争议。在这项工作中,我们首先开发了一种基于图论的算法,以建立一个完整的合成气转化为甲醇、乙烯酮和甲烷的反应网络。结合密度泛函理论(DFT)计算,通过反应相图系统研究了合成气转化氧化锌(ZnO)的活性和选择性。在实验中观察到了关键中间体乙烯酮,这在这项工作中首次得到了理论上的证实。发现 ZnO 表面的演变是不同产品选择性的关键因素。发现甲醇生产比具有低氧空位浓度的 ZnO 表面更有利。随着氧空位的增加,主要产物逐渐从甲醇演变为乙烯酮,最后演变为甲烷。因此,总反应活性也增加。我们对反应相图的预测最终得到了微动力学模型的验证。
更新日期:2021-10-01
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