Study on hydrodeoxygenation mechanism of anisole over Ni (111) by first-principles calculation

Abstract

Anisole, as an aromatic oxygenate lignin model compound, which can be selectively cleaved into benzene over Ni/C at high temperature. On the basic of experimental results, the hydrodeoxygenation (HDO) mechanism of anisole was investigated on clean Ni (111) surface by using computational techniques. Based on static energies, the microkinetic modeling on clean Ni (111) and H-covered Ni (111) were built in which the modeling of H-covered Ni (111) approximately simulated the real catalytic system under lower temperature and higher H2 pressure. As a result, the microkinetic analysis proved the phenol was the major product in the anisole decomposition on clean Ni (111) surface. However, the phenol was preferred to decompose rather than desorb from Ni surface because of the high desorption energy, suggesting that the benzene mainly originated from the secondary dissociation of phenol. Differently, the decreasing of energy barrier for anisole hydrogenation led to the formation of methylcyclohexane as main product on H-covered Ni (111) surface by microkinetic analysis. The differences in products distribution between Ni (111) and H-covered Ni (111) provided a mechanistic understanding for anisole conversion under different experimental conditions.