Preparation of Cu/SBA-15 catalysts by different methods for the hydrogenolysis of dimethyl maleate to 1,4-butanediol

Mesoporous siliceous SBA-15-supported Cu catalysts have been prepared by different methods and systematically characterized. The results revealed that the incipient wetness impregnation (IWI) method gives poor dispersion of copper species, whereas much better dispersion is found in catalysts prepared by the deposition precipitation (DP), grafting, and homogeneous deposition precipitation (HDP) methods. The Cu/SBA-15 catalyst prepared by the grafting method is rich in Cu+, while a partial destruction of the hexagonal mesostructure of SBA-15 occurs in the catalyst prepared by the HDP method. In gas phase hydrogenolysis of dimethyl maleate (DMM) to 1,4-butanediol (BDO), the hydrogenolysis activities of the catalysts follow the sequence of the metallic Cu surface areas; the catalyst prepared by the HDP method exhibits the highest activity and selectivity. Irrespective of the much smaller metallic Cu surface area of the catalyst prepared by the grafting method, this catalyst exhibits only slightly lower activity than that prepared by the DP method, suggesting that Cu+ also participates in DMM hydrogenolysis. The reaction conditions are further investigated over the Cu/SBA-15 catalyst prepared by the HDP method, aiming to obtain a high yield of BDO.