Benzaldehyde reduction over Cu-MCM-41 catalyst: Influence of the Si/Cu ratio during hydrothermal synthesis on the structure and catalytic properties

This work aims to evaluate the catalytic performances of mesoporous MCM-41 materials modified by the insertion of a copper heteroatom in the Gas-phase reduction of benzaldehyde under hydrogen flow. The catalysts were synthesized by the hydrothermal method and characterized by AAS, XRD, FTIR, and N₂-physical adsorption/desorption techniques to improve controlling the entire functionalization sequence of materials. It was established that the hexagonal structure of MCM-41 displays good crystallinity due to the presence of the characteristic peak of this structure. The introduction of a metallic element such as copper in the structure of MCM-41 showed a more or less significant modification of the structural and textural properties. The performed catalytic properties in a reaction temperature range of 160–250 °C showed that the Cu-MCM-41 catalysts were stable and led to good benzaldehyde conversion rates ranging between 0 and 31%. Benzyl alcohol and toluene were obtained through consecutive hydrogenation/hydrogenolysis reactions, while benzene was formed via a concomitant hydrogenolysis reaction. The yields of the obtained hydrogenation and hydrogenolysis products (benzyl alcohol, toluene, and benzene) were highly dependent on the copper content and reaction temperature.