MCM-41 Supported Copper-Based Catalysts: Physicochemical Characterizations and Catalytic Performances in the Gas Phase Hydrogenation of Benzaldehyde

We are reporting in this study the preparation of copper-based catalysts supported on MCM-41 mesoporous molecular sieves with different Si/Cu ratios (10 and 50) via two steps: firstly, the synthesis of the mesoporous material MCM-41 by the hydrothermal method and secondly, the preparation of the supported catalysts by a wet impregnation method. The structural and textural properties of the supported catalysts were determined using the atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), N₂-physical adsorption, and scanning electron microscopy (SEM) techniques. The catalytic properties of the supported materials have been evaluated on the reduction reaction of benzaldehyde at atmospheric pressure and in the gas phase. The yields of the obtained hydrogenation and hydrogenolysis products (benzyl alcohol, toluene, and benzene) were highly dependent on the copper content and reaction temperature, and preferentially formed in the whole range of reaction temperatures 160–250 °C. The observed selectivity of the hydrogenation and hydrogenolysis reactions towards the production of various products suggests the existence of catalytic active species of different particle sizes in the two catalyzed reactions.