The potential of hydropyrolysis as a route for coal liquefaction

摘要

AbstractThe use of sulphided molybdenum (Mo) as a dispersed catalyst enables tar yields of ∼ 60 daf coal to be achieved for bituminous coals (80–83 dmmf C) in fixed‐bed hydropyrolysis using relatively low‐severity conditions. Sulphur‐containing Mo precursors, such as ammonium dioxydithiomolybdate are the most effective, Mo concentrations of 0.2 being required to achieve maximum tar yield. Ion‐exchange preparation procedures offer the potential of improving catalyst dispersions, and concentrations as low as 0.02 are effective when Mo is ion‐exchanged onto coals coated with hydrous titanium oxides. Iron sulphides are much less effective than in direct liquefaction because of the higher heating rates used in hydropyrolysis. Low‐rank coals can yield up to 50 tar without catalyst, and improvements in yield on catalyst addition are considerably less than for bituminous coals. Exinite has a positive synergistic effect on vitrinite conversion in catalytic hydropyrolysis for one of the bituminous coa