This paper presents an overview of a research program being pursued at the Research Institute of King Fahd University of Petroleum and Minerals is aimed at development of suitable catalysts for hydrocracking of the vacuum gas oils from Arabian Light crude to obtain higher quality distillate products.
The newly developed high-performance hydroprocessing catalysts are based on amorphous silica alumina and modified zeolites. Active metals have been incorporated into these novel supports to prepare several catalyst formulations for both the stages of the conventional fixed-bed hydrocrackers. These novel catalysts have been characterized by sophisticated techniques and evaluated for their performance. Some of the formulations of developed catalysts have exhibited high performance in terms of hydrodesulfurization and cracking activities. These catalysts are being further developed, comprehensively characterized, and thoroughly evaluated in order to come up with a tailor-made catalyst formulation for hydrocracking of heavy fractions of Arabian Light crude oil.
The conversion of the heaviest fraction of crude oil into more valuable light products has long been a primary goal of the petroleum refining industry. Today, this goal has become even more important as the demand for heavy fuel oil and known reserves of the lighter crudes continue to decline. The market for residual fuel oil has been shrinking because of the steady increase in demand for middle distillates. Therefore, research has been aimed- -especially in U.S., Canada, Japan and in Europe- -to upgrade residuum. In some refineries, a large proportion of residues from distillation is not treated any further. It should be noted that about 30 percent of the Kingdom's refined product output is heavy fuel oil and only 14 percent is gasoline1. With the commissioning of hydrocracker and continuous catalytic reformer units at Ras Tanura refinery, the overall conversion should have increased.
The overall objective of residue upgrading is to obtain additional quantities of desirable products of a higher hydrogen-carbon atomic ratio. It is worth noting that H/C ratio lies between 1.8 and 2.1 for middle distillates and lubricants, between 1.6 and 1.8 for residues, and around 1.5 for heavy crude oils. Atmospheric residues have components like resins and asphaltenes that are the most hydrogen deficient and relatively rich in carbon as well as in sulfur, nitrogen, nickel and vanadium. In general, the H/C atomic ratios of atmospheric residue, resins and asphaltenes are 1.41, 1.33 and 1.06, respectively2. The presence of these heavy molecules causes difficulties in the catalytic processing of heavy feedstock either by hyd