Liquid phase hydrogenation of maleic anhydride and intermediates on copper-based and noble metal catalysts

The liquid phase hydrogenation of maleic anhydride and intermediates was investigated using copper-based and noble metal catalysts. The experiments were performed in a stirred tank slurry reactor in discontinuous as well as continuous operation. Copper chromites and noble metal catalysts were found to be suitable for the hydrogenation of maleic anhydride. However the hydrogenation of succinic anhydride proceeded with high selectivity to gamma-butyrolactone and 1,4-butanediol on copper zinc catalysts, whereas other copper catalysts revealed no activity in the formation of 1,4-butanediol. Selective sorption interactions of succinic anhydride with the zinc surface were assumed to be responsible for this effect. Starting from gamma-butyrolactone all copper catalysts were active in the formation of 1,4-butanediol while noble metal catalysts showed no or little activity. Kinetic models have been proposed for the hydrogenation of maleic anhydride and intermediates on the basis of experimental data obtained in a continuously operated stirred tank slurry reactor.