The shortage of crude oil supply placed an increased emphasis on methods of upgrading petroleum residue, heavy oil and oil bearing sands. However, the high metal content of these stocks will result in poisoning of the catalysts used in processes such as catalytic cracking, hydrocracking and hydrotreating.
For treatment of high metal feedstocks, processes such as coking, deasphalting, use of a hydrogen-donor solvent, extraction with acid, and precipitation with a polar solvent are used.
Selection of the most economic process route for residuum conversion is not straightforward; however, if crude oil price continues growing upward more rapidly than solid fuels do and if high sulfur tar and coke prices remain comparable with those of other fuels, then processes fo elimination of high sulfur by-products will become more attractive. With this in view, it is apparent that residuum hyroprocessing will play a major role in residuum conversion in the future.