Insight into the formation mechanism of C[sbnd]C chain in ethanol synthesis at the interface of partially hydroxylated γ-Al2O3 (110D) surface and polyethylene glycol solvent

Abstract

A detailed reaction network has been constructed for ethanol synthesis at the interface of partially hydroxylated γ-Al2O3 (110D) surface and polyethylene glycol (PEG) solvent using periodic density functional theory calculations, which provides a first glimpse into the plausible reaction mechanism for ethanol synthesis. The formation of key intermediate CH3 is the rate determining step of the overall process, accompanied with a reaction barrier of 1.29 eV. Based on thermodynamic, kinetic data and Bader charge analyses, we confirm that the methyl carbonylation is responsible for the initial CC bond formation, which needs to overcome a 0.96 eV barrier and is exothermic by1.67 eV. The hydroxyl coverage conditions formed by dissociative adsorbed H2O govern the key active sites on the γ-Al2O3 (110D) surface which in turn has a significant role in determining the dominant reaction mechanism. Meanwhile, the absence of PEG solvent also affects the optimal reaction route of ethanol synthesis and the essential reason is the existence of fairly strong hydrogen bonds. Our findings manifest the interface located between partially hydroxylated γ-Al2O3 (110D) surface and PEG solvent possesses decent catalytic performance for ethanol synthesis and facilitates providing new strategy to tune and design promising CuZnAl catalysts for ethanol synthesis.