One-pot synthesis of 1,4-butanediol via the deep hydrogenation of maleic anhydride over Cu-xMo/SiO₂ catalysts

Sustainability issues have led to a gradual market expansion for the 1,4-butanediol (BDO) monomer of the biodegradable plastics to replace conventional plastics. Maleic anhydride (MA) can be derived from the oxidation of bio-based furfural or fructose. Although the hydrogenation of MA can produce a series of products, including succinic anhydride (SA), γ-butyrolactone (GBL), BDO and tetrahydrofuran (THF), the one-pot deep hydrogenation of MA to BDO or THF under mild conditions has been rarely reported in the literature until now. Herein, we report the production of BDO from the one-pot deep hydrogenation of MA over a Cu-0.03Mo/SiO₂ catalyst, achieving 100% MA conversion and 88.3% BDO yield. The Cu-0.03Mo/SiO₂ catalyst also showed good long-term stability without obvious loss in activity or BDO selectivity during a 160 h time-on-stream test. Doping Mo to Cu/SiO₂ catalysts in an optimal amount adjusted the distribution of Cu⁰/Cu⁺ species and modulated the interaction of Cu-SiO₂ and surface acidity, so that the activation of hydrogen, MA and relevant intermediates can become balanced, in addition to the restriction of side-reactions. This study provides potential for the green synthesis of BDO with non-precious Cu-based catalysts.