Liquid-phase hydrogenation of dimethyl maleate to 1,4-butanediol over a sorbitol-modified Cu@C/ZnO catalyst

With the growing global demand for biodegradable plastics, the hydrogenation of dimethyl maleate (DMM) to produce 1,4-butanediol (BDO), raw materials for poly(butylene succinate), has become one of the hot spots in chemical industry. In this work, we synthesized a series of Cu@C/ZnO–S_x catalysts by the method of sorbitol modification for the liquid-phase hydrogenation of DMM. The modification with appropriate sorbitol led to a decoration of carbon on catalyst surface, which improved the copper dispersion and Cu⁺/(Cu⁰ + Cu⁺) molar ratio in the Cu@C/ZnO–S_0.08 catalyst. The carbon decoration not only promoted the formation of more copper species having stronger interaction with ZnO, but also enhanced the absorption of ester on catalyst surface. These distinctive properties contributed to the high performance of the Cu@C/ZnO–S_0.08 catalyst in DMM hydrogenation, achieving an excellent BDO yield of 98.4% and superior reusability. The insights into the roles of sorbitol modification could give valuable guidance to the further design of high performance catalysts for esters hydrogenation.