Recovery of deactivated γ-Al2O3 catalyst used in chlorination of benzene by a hybrid method: Acid washing and thermal treatment

Abstract

This study implements a hybrid method to revive the deactivated γ-Al₂O₃ catalyst used in the chlorination of waste-recycled benzene in vinyl chloride production by Arvand Petrochemical Company. The method includes chemical and thermal remedies: acid washing and heating under steam. The acidity strength of two different acids, HCl and HNO₃, and furnace temperature are perceived as influential variables in the reviving process in three levels of 0.5, 1, and 1.5 M, and 450, 500, and 550 °C. Characterization analyses including XRD, BET, SEM, and FTIR are employed to compare fresh, deactivated, and revived catalysts. The results suggested that HCl with a concentration of 0.5 M and a furnace temperature of 500 °C triggered the optimal conditions to recover the specific surface area. It is proven that HNO₃ even in the lowest concentration could destroy the catalyst structure. On the contrary, thermal treatment was insufficient to revive the deactivated catalyst.