Direct Coal Liquefaction

This chapter explains coal liquefaction, which is recognized as a competition between hydrogenation to liquid products and destructive distillation that forms solids. The principal objective of coal liquefaction is the production of liquid hydrocarbon distillate products from a coal's mostly aromatic structure to be used as transportation fuels or chemicals. Coal rank and composition are primary factors that influence liquefaction behavior and, although some of that influence may be overcome by increasing process severity or the use of catalysts, these options may be counterproductive in reducing operating expenses. The chapter explains that coals of high total sulfur content are generally derived from high saline, marine peat-forming environments in which bacteria are more active. Contribution of lipid-like organic materials by bacteria to the biomass may have as much impact on total conversion and oil production during liquefaction as sulfur.