Hydrogenation of maleic anhydride to succinic anhydride over nickel/clay catalysts

Hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) over Ni/clay catalysts prepared by an impregnation method has been studied at different temperatures, Ni contents, pressures and weighted hourly space velocity (WHSV). The catalytic activity was greatly influenced by the temperature, Ni content, WHSV and pressure. A 97.1 % MA conversion with 99.6 % selectivity to SA was obtained over 5 %wt catalyst at 180 A degrees C and at a pressure of 1 MPa H-2. The catalysts were characterized by an array of techniques, including X-ray diffraction (XRD), H-2 temperature-programmed reduction (TPR) and thermogravimetric analysis (TGA). XRD and TPR studies showed that nickel was present as Ni2+ species on the support. Increasing the calcination temperature up to 650 A degrees C led to the destruction of the support structure, as observed by TGA, while a calcination temperature of 550 A degrees C gave the best results. Catalyst deactivation studies showed that the catalyst has a long lifetime, the yield of SA remaining better than 90 % even after a reaction time of 60 h. Studies on the catalyst induction showed that the presence or absence of an induction period was determined by the type of hydrogenation catalyst.