Carbon-Modified Alumina and Alumina-Carbon-Supported Hydrotreating Catalysts

Two types of supports, carbon-modified alumina and alumina-carbon, were prepared in this investigation. These supports were used to prepare hydrotreating (HDT) catalysts for Maya heavy crude. It was found that, when carbon was added to the alumina matrix and the carbon was then burned, pores having larger diameter were generated. The average pore diameter of the support increased with increasing amount of carbon in the alumina. However, when the carbon was not burned, the pore size decreased with added carbon. The hydrotreating activity results show that, because of the larger pore diameter and higher pore volume, the modified-alumina-supported PCoMo catalysts have slightly higher activities than the alumina-carbon-supported catalysts. The effects of additives, boron and phosphorus, on the hydrotreating of heavy oil were also compared. It was found that P-containing catalysts have higher activities than B-containing catalysts. It was also found that, when boron-containing catalyst were prepared at higher pH, they had higher hydrodemetalation (HDM) activities. Deactivation studies showed that the presence of carbon in the support might hinder rate of deactivation during hydrotreating of heavy oil.