期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 124, 期 27, 页码 14658-14663出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.0c03125
关键词
-
资金
- Swedish Research Council
- state of Baden-Wurttemberg through bwHPC (bwunicluster)
- Helmholtz Association
- state of Baden-Wurttemberg through bwHPC (JUSTUS) [RV bw17D011]
- Rontgen-Angstrom collaboration Time-resolved in situ methods for design of catalytic sites within sustainable chemistry
Acidity is considered a key factor in zeotype-based catalysts. Here, the effect of acidity in the methanol-to-DME reaction is investigated using first-principles calculations and microkinetic modeling, thereby establishing a connection between acididity and kinetics. The CHA, MFI, and BEA frameworks are investigated, and the acidity of the Bronsted hydroxyl group is varied by exchanging a T-site Si with Al, B, Ga, and Fe in the zeolites, along with SAPO-34, Mg-AIPO-34, Zn-AlPO-34, and Ti-AlPO-34 zeotypes with the CHA structure, and as a result, the Bronsted hydroxyl group spans a wide range of acidity. Clear trends in adsorption and transition-state energies are found and by means of linear regression, we obtain scaling relations of relevant energies that are later used as input in a mean-field steady-state microkinetic model. This study confirms that both the shift in frequency of the Bronsted hydroxyl stretch, Delta f(OH), caused by adsorption of CO and the ammonia adsorption energy, Delta E-ammonia, on the Bronsted site are equivalent descriptors for the acidity of the Bronsted acid site and the reactivity of the different zeotypes relevant for the methanol-to-DME reaction. It further shows that a full microkinetic model is needed to accurately describe the reaction over the whole range of temperatures. However, if focusing on low temperatures, where the associative mechanism is dominating the reaction, a simple rate-determining step model is actually able to describe the results with satisfying agreement (deviation of the rate by less than a factor of two).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据