Insights into the copper silicate modification on Cu/ZnO/Al2O3 catalysts during HPA hydrogenation: influence of copper species on catalytic selectivity†

Abstract

In this study, different amounts of copper silicate-modified Cu-based catalysts with a fixed Cu/Zn/Al molar ratio were prepared via a coprecipitation method, and their catalytic activity in the hydrogenation of hydroxypivalaldehyde (HPA) to neopentyl glycol (NPG) was investigated. The reaction mechanism of copper silicate for copper-catalyzed aldehyde hydrogenation was explored using various characterization methods. Results showed that an appropriate amount of copper silicate improved the interaction between the metal components, augmented the surface area of the catalyst, captured more H₂ and HPA, and thus promoted the reaction. It also promoted the reduction of copper active species and optimized the dispensation of Cu⁺ and Cu⁰ on the catalyst surface, reduced the occurrence of side reactions, and improved the selectivity for NPG. Under the reaction conditions of 373 K, 3.5 MPa, and LHSV = 6 h⁻¹, the enhanced catalyst exhibited exceptional catalytic performance, with an HPA conversion rate of 99.8% and an NPG selectivity of 94.4%.