Deactivation and regeneration of Cu/SiO(2) catalyst in the hydrogenation of maleic anhydride. Kinetic modeling

In this work, the deactivation of a Cu(10%)/SiO(2) catalyst in the gas-phase hydrogenation of maleic anhydride (MA) was studied. The reaction was performed between 170 and 220 C, at atmospheric pressure and using two contact times [MathML equation]: 11.9 and 23.8 g cat. h/mol MA. The Cu(10%)/SiO(2) catalyst was prepared by the wetness impregnation method and characterized by N(2) physisorption at -196 C, N(2)O decomposition at 90 C, X-ray diffraction and temperature programmed reduction. From this characterization, it was concluded that catalyst is formed by large metal copper crystallites with little or none interaction with silica surface. Under the conditions used in this work, the Cu(10%)/SiO(2) catalyst was highly selective to succinic anhydride (SA) while MA conversion dropped drastically with time. Both high selectivity to SA and rapid catalyst deactivation can be explained considering different types of MA interaction with the large metal copper crystallites. Catalyst regeneration feasibility under two different atmospheres, oxidizing and reducing, was also analyzed. The experimental results were successfully fitted, by non-linear regression, using a deactivation model with residual activity (DMRA). This model predicts satisfactorily the deactivation of Cu(10%)/SiO(2) in the gas-phase hydrogenation of MA, both for fresh and regenerated catalysts, under the experimental conditions used in this work.