ONE-STAGE AND 2-STAGE COPROCESSING OF COAL AND PETROLEUM RESIDUES

The potential of two atmospheric and three vacuum petroleum residues a s feedstocks for coprocessing with a UK bituminous coal has been asses sed. In a simulation of the British Coal Corporation's two-stage liqui d solvent extraction process, the residues were first examined as pros pective solvents in the extraction stage. Coal conversions varied from about 6-37%, the best yields being obtained from residues with a high asphaltene content or a high (aromatic and polar) content in the malt ene fraction. These yields compare poorly with those obtainable with c oal-derived solvents. In two cases, catalytic prehydrogenation of the petroleum residue improved conversions to about 65%, but these results were not reproducible. One-stage coprocessing at 450-degrees-C and 12 MPa hydrogen pressure was much more successful. Coal conversions of a bout 75% were obtained at optimum conditions. Conversions under one-st age coprocessing were insensitive to the nature of the residue.