Bioethanol Guerbet condensation reaction: Construction of a highly active and stable catalytic system

Abstract

The production of n-butanol from bioethanol via Guerbet condensation is a green process route. However, this process has issues such as easy leaching of metal components from the catalyst and the impact of byproduct water on catalytic activity and stability. To inhibit metal leaching, core-shell structured 10%Ni/HAP@x-g-C3N4 and 10%Ni-5%Cu/HAP@x-g-C3N4 catalysts were prepared by incorporating graphitic carbon nitride (g-C3N4). The catalysts were characterized by means of XRD, nitrogen adsorption-desorption, ICP-OES, XPS, and HRTEM, and their catalytic performance was evaluated subsequently. The results indicate that the interaction between N and metals promoted the catalyst's activity and stability. To address this issue, acetal was introduced to construct an integrated reaction of ethanol Guerbet condensation and acetal hydrolysis. The acetal hydrolysis consumed the byproduct water, with the hydrolysis products—ethanol and acetaldehyde—not complicating the system. This integration not only promoted the Guerbet condensation of ethanol, but also further improved the activity and stability of the 10%Ni-5%Cu/HAP@15-g-C3N4 catalyst. The yield and selectivity of n-butanol reached 30.3% and 56.2%, respectively, and the yield of n-butanol only decreased by 1.9% after five consecutive reaction cycles.