Pressure-temperature microscopy of coal liquefaction

A pressure-temperature microscopy system (PTM) has been developed for obtaining observations on coals and heavy hydrocarbons at elevated temperatures and hudrogen pressures commonly used in the hydroprocessing of coal, coal liquids, and petroleum residua. A Pittsburgh #8 seam coal, from near New Eagle in Washington County located south of Pittsburgh, Penna., was extensively characterized by petrographic analysis, proximate and ultimate analysis, Gieseler plastometer, and Ruhr dilatometry as well as data on grindability, ash characteristics, and oxidation properties. Novel direct microscopic observations at elevated temperatures and pressures with catalysts give observable changes in phase transition behavior of coal. Direct microscopic observations of fresh vitrain particles at elevated temperature and high nitrogen pressure in the presence of a tin chloride catalyst show plastic deformation. Upon replacement of nitrogen by pressurized hydrogen, individual vitrain particles are observed to liquefy in the presence of molten tin. After liquefaction, further temperature increase at 1950 psig hydrogen results in the formation of mesophase and the segregation of the molten tin.Pressure-temperature microscopy is also presented on the liquefaction behavior of a solvent-refined coal (SRC) from Wilsonville, Ala. Additional pressure-temperature microscopy is presented on the tin-catalyzed co-liquefaction behavior of the solvent-refined coal with the Pittsburgh #8 seam vitrain. The pressure-temperature microscopy of the liquefaction experiments and mesophase development have been video recorded and are available for viewing.