Effect of Ni loading and calcination temperature on catalyst performance and catalyst deactivation of Ni/SiO2 in the hydrodechlorination of 1,2-dichloropropane into propylene

The hydrodechlorination of 1,2-dichloropropane (DCPA), a chlorinated organic waste which is produced in the epichlorohydrin process, to propylene was carried out over Ni/SiO(2) catalysts. The effects of Ni loading and calcination temperature on catalyst performance and catalyst deactivation of Ni/SiO(2) were systematically investigated. The Ni/SiO(2) catalysts efficiently converted DCPA into propylene in 95% selectivity or higher. The particle size of Ni on SiO(2) was strongly related to the catalyst stability. In terms of the effect of Ni loading, the largest Ni particles on SiO(2) showed the best durability against deactivation. A series of TPR and UV-DRS measurements revealed that nickel hydrosilicate was formed as the result of the interaction between Ni and SiO(2). Nickel hydrosilicate was found to be responsible for the catalyst stability leading to low catalyst deactivation. HCl adsorption on Ni/SiO(2) was the main reason for catalyst deactivation. HCl modified the crystal structure of metallic Ni to NiCl(2) and led to irreversible deactivation and metal sintering.