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Density Functional Theory (DFT) and Kinetic Monte Carlo (KMC) Study of the Reaction Mechanism of Hydrogen Production from Methanol on ZnCu(111)

Zuo, Zhi-Jun, Gao, Xiao-Yu, Han, Pei-De, Liu, Shi-Zhong, Huang, Wei
The Journal of Physical Chemistry C 2016 v.120 no.48 pp. 27500-27508
alloys, carbon dioxide, catalysts, dehydrogenation, formaldehyde, hydrogen, hydrogen production, methanol, oxidation, physical chemistry, reaction mechanisms, steam
Cu/ZnO-based catalysts have been widely used for methanol decomposition (MD), partial oxidation of methanol (POM), steam reforming of methanol (SRM), and oxidative steam reforming of methanol (OSRM). In this work, we systematically studied all possible reaction paths involved in MD, POM, SRM, and OSRM on ZnCu alloys (111) using density functional theory (DFT). On the basis of these results, Kinetic Monte Carlo (KMC) simulations show that the rate-limiting step of the four reactions is CH₂O formation from CH₃O dehydrogenation. The reaction pathway of MD occurs via the direct decomposition of CH₃OH, and the main reaction pathways of POM and SRM occur via CH₂OO and CH₂OOH, respectively. There are two main reaction pathways of OSRM as follows: one occurs via CH₂OO, whereas the other occurs via CH₂OOH. Finally, according to the results of sensitivity analysis, some possible modifications to improve the CO₂ selectivity and turnover frequency (TOF) of H₂ for OSRM on Cu/ZnO-based catalysts are also presented. The results may be useful for designing and optimizing Cu-based catalysts for MD, POM, SRM, and OSRM.