Gas phase hydrogenation of maleic anhydride at low pressure over silica-supported cobalt and nickel catalysts.

CAMILO I. MEYER; SILVINA A. REGENHARDT; ALBERTO J. MARCHI; TERESITA F. GARETTO

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Año: 2011

0926-860X

The gas-phase hydrogenation of maleic anhydride over Ni/SiO2 and Co/SiO2 catalysts,prepared by the incipient wetness impregnation method, was studied. The catalytic testswere carried out at 1 bar pressure, between 170 and 220ºC and 0W FMA in the range 5-25g.h.mol-1. In this work, the product distribution was different to those obtained at highpressures, previously reported in the open literature. Both Ni/SiO2 and Co/SiO2 catalystswere active for the selective hydrogenation of maleic anhydride (MA) into succinicanhydride (SA). Subsequently, SA was converted to g-butyrolactone (GBL) andpropionic acid (PA). Neither tetrahydrofurane nor butanediol were detected at thereactor outlet. GBL/PA ratio was strongly depending on the metallic catalyst andtemperature. At 170ºC, Ni/SiO2 was more selective to GBL than Co/SiO2. Besides, withNi/SiO2, GBL formation rate diminished during the experiment while PA production showed a small increase. Instead, over Co/SiO2, both the PA and GBL formation rate decayed with time on stream. At 220ºC, Co/SiO2 showed a higher initial selectivity to GBL than Ni/SiO2. However, the GBL formation rate diminished more rapidly with Co/SiO2.than with Ni/SiO2. Thus, both catalysts gave similar selectivity to GBL after 3 h reaction at 220ºC. The observed catalyst deactivation was attributed to carbonaceous species of different nature deposited on the metallic phase during reaction. The amount and type of these species depends on both metal catalysts and reaction conditions. Selectivity and stability of Ni/SiO2 and Co/SiO2 catalysts is explained on the basis oftheir hydrogenolytic activity.