Quantifying the lateral interactions between adspecies is necessary in the development of truly predictive, theoretical models for bimetallic catalysts, as they will significantly affect the coverage and diffusion of adspecies and therefore the heterogeneous catalytic environment. To that end, we have characterized the benzene-benzene lateral interactions on a Pt (111) surface and a Pt3Sn (111) surface alloy. This coverage-dependent adsorption behavior was incorporated into a kinetic model for each surface and used to simulate the temperature-programmed desorption (TPD) spectra. We benchmarked our simulated spectra by comparing it to experimental TPD [1]. We found that it is imperative to incorporate the effect of surface coverage in these theoretical models if the desorption behavior is to be accurately predicted. Furthermore, we found that a mean-field model is sufficient in describing the benzene-benzene lateral interactions. Using our models, we were able to interpret the desorption behavior at an atomistic level and provide a deeper level of insight into these systems. We also found that the adsorption of benzene was significantly weaker on the Pt3Sn (111) than on Pt (111), and as such, we were able to assign the monolayer desorption of benzene to a TPD peak previously attributed entirely to multilayer benzene desorption [1]. While these ultra-high vacuum studies provide significant insight into the reactions occurring on the catalyst's surface under typical experimental conditions, liquid bio-oil has a high concentration of water which can significantly affect the surface species and reaction mechanisms[2]. In order to understand how water could affect the HDO mechanisms of phenol on Fe (110), we examined the influence of an aqueous environment on the HDO mechanism and the results show that the presence of water affects the elementary reactions involving the movement of hydrogen, promoting hydrogenation and tautomerization mechanisms. Furthermore, the presence of hydroxyl on the Fe (110) surface was found to be crucial in hydrogenating the aromatic ring with the surface hydroxyl acting as Brønsted acid sites.

Elucidating the mechanism for the catalytic hydrodeoxygenation of phenols

255th National Meeting (2018)

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