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首页> 外文期刊>Catalysis science & technology >Improving alkane dehydrogenation activity on gamma-Al2O3 through Ga doping
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Improving alkane dehydrogenation activity on gamma-Al2O3 through Ga doping

机译：改善烷烃脱氢活动通过Ga gamma-Al2O3兴奋剂

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Nonoxidative alkane dehydrogenation is a promising route to produce olefins, commonly used as building blocks in the chemical industry. Metal oxides, including gamma-Al2O3 and beta-Ga2O3, are attractive dehydrogenation catalysts due to their surface Lewis acid-base properties. In this work, we use density functional theory (DFT) to investigate nonoxidative dehydrogenation of ethane, propane, and isobutane on the Ga-doped and undoped (100) gamma-Al(2)O(3)via the concerted and stepwise mechanisms. We revealed that doping (100) gamma-Al2O3 with Ga atoms has significant improvement in the dehydrogenation activity by decreasing the C-H activation barriers of the kinetically favored concerted mechanism and increasing the overall dehydrogenation turnover frequencies. We identified the dissociated H-2 binding energy as an activity descriptor for alkane dehydrogenation, accounting for the strength of the Lewis acidity and basicity of the active sites. We demonstrate linear correlations between the dissociated H-2 binding energy and the activation barriers of the rate determining steps for both the concerted and stepwise mechanisms. We further found the carbenium ion stability to be a quantitative reactant-type descriptor, correlating with the C-H activation barriers of the different alkanes. Importantly, we developed an alkane dehydrogenation model that captures the effect of catalyst acid-base surface properties (through dissociated H-2 binding energy) and reactant substitution (through carbenium ion stability). Additionally, we show that the dissociated H-2 binding energy can be used to predict the overall dehydrogenation turnover frequencies. Taken together, our developed methodology facilitates the screening and discovery of alkane dehydrogenation catalysts and demonstrates doping as an effective route to enhance catalytic activity.
机译：Nonoxidative烷烃脱氢是一种很有前途的路线生产烯烃,常用化学工业的基石。氧化物,包括gamma-Al2O3 beta-Ga2O3,脱氢催化剂由于他们的吸引力表面路易斯酸碱属性。我们用密度泛函理论(DFT)调查nonoxidative脱氢乙烷、丙烷、异丁烷Ga-doped和纯的(100)gamma-Al (2) O(3)通过协调和分段机制。兴奋剂(100)gamma-Al2O3与Ga原子脱氢的显著改善活动通过减少碳氢键活化壁垒共同青睐的活动机制,提高整体脱氢周转频率。确定了分离,氢结合能烷烃的活动描述符脱氢,占的力量刘易斯的酸度和碱度的活跃网站。的分离,氢能源和有约束力激活壁垒的速率决定步骤共同和分段机制。我们进一步发现碳正离子的稳定性是一个定量reactant-type描述符,关联的碳氢键活化障碍不同的烷烃。烷烃脱氢模型,抓住了酸碱催化剂表面性质的影响(通过分离,氢结合能)和反应物替换(通过碳正离子稳定)。分离,氢可以用来结合能预测整体脱氢营业额频率。方法筛选和便利发现烷烃脱氢催化剂兴奋剂是一种有效的途径提高催化活性。

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