Liquid Phase Hydrogenation of Maleic Anhydride to 1,4-Butanediol in a Packed Bubble Column Reactor

The liquid phase hydrogenation of maleic anhydride was investigated in a packed bubble column reactor using different copper-based catalysts. A copper-zinc catalyst was found to be active in the formation of 1,4-butanediol, whereas on zinc-free copper catalysts, mainly succinic anhydride and γ-butyrolactone were formed. At suitable reaction conditions, maleic anhydride hydrogenation over a copper-zinc catalyst gave valuable products with high yield and selectivity whereas succinic anhydride was absent in the reactor outlet. Based on a three-phase reactor model and a kinetic model of the reaction mechanism, the influence of reaction conditions on reactor performance was determined. It was observed that the use of large particles and a high axial dispersion of liquid phase is a necessary condition for the feasibility of a "one-step-hydrogenation" of highly concentrated maleic anhydride feed solutions because of a significant decrease of succinic anhydride formation rate.