Active sites and mechanism of aqueous phase methanol dehydrogenation on Pt/Al2O3 catalysts from multiscale modeling, microkinetic modeling, and operando spectroscopy
Ricardo A. García Cárcamo , Tianjun Xie , Bryan J. Hare , Carsten Sievers , Rachel B. Getman
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引用次数: 0
Abstract
One of the most important scientific challenges of the time is to design catalysts that produce H2 from “minimum ” sources. One way to do this is by aqueous phase reforming (APR) of sugar alcohol molecules derived from biomass. However, to date, H2 yields have been disappointing, indicating a need to optimize catalysts and reaction conditions to improve H2 production. This requires a detailed understanding of the APR mechanism. There are three primary steps: dehydrogenation, decarbonylation, and water gas shift. However, the details of these steps remain unknown due to the large and complex structures of the reactant molecules, the aqueous reaction conditions, and the participation of multiple types of active sites in the mechanism. To begin to address these knowledge gaps, herein we study the effect of liquid solvent and multiple types of active sites on the mechanism of CH3OH dehydrogenation. Specifically, we use a combination of multiscale modeling, microkinetic modeling, and Fourier transform infrared spectroscopy to determine the mechanism of CH3OH dehydrogenation on Pt/Al2O3 catalysts. We investigate sites on the terraces of large Pt particles as well as sites at the Pt/Al2O3 perimeter and the influence of liquid on both. We show that the reaction is predominantly carried out on terrace sites due to inhibition by strongly bound molecules at perimeter sites. We further show that water plays a significant role in the CH3OH dehydrogenation mechanism on Pt terrace sites but that these changes do not influence the observed rate of CH3OH consumption.
期刊介绍:
The Journal of Catalysis publishes scholarly articles on both heterogeneous and homogeneous catalysis, covering a wide range of chemical transformations. These include various types of catalysis, such as those mediated by photons, plasmons, and electrons. The focus of the studies is to understand the relationship between catalytic function and the underlying chemical properties of surfaces and metal complexes.
The articles in the journal offer innovative concepts and explore the synthesis and kinetics of inorganic solids and homogeneous complexes. Furthermore, they discuss spectroscopic techniques for characterizing catalysts, investigate the interaction of probes and reacting species with catalysts, and employ theoretical methods.
The research presented in the journal should have direct relevance to the field of catalytic processes, addressing either fundamental aspects or applications of catalysis.