CO-REFINING OF COAL AND PETROLEUM - NEW ANALYTICAL METHODS AND RESULTS

A UK bituminous coal was co-processed with five different petroleum re sidues, and with hydrotreated feedstocks, in a simulation of the Briti sh Coal Corporation's two-stage liquid solvent extraction process. One -stage co-processing in the presence of a catalyst and hydrogen gas wa s also investigated. The feedstocks and products were analysed by a va riety of procedures, some of which were especially devised, e.g. simul ated distillation by supercritical fluid chromatography, determination of the functionality of nitrogen and sulphur, and assessment of the c ontributions of coal and petroleum to the products by stable-isotope m ass spectrometry and size-exclusion chromatography. In low-severity co -processing the best yields were found to be associated with the conte nt of n-pentane insoluble (asphaltene) aromatics in the solvent. Singl e-stage co-processing gave improved yields. Progressive changes in the composition of the solvent during recycle were identified. No changes in the distribution of nitrogen among different functional groups dur ing co-processing were observed, but the formation of new sulphur grou ps was observed.