Reactions of coal liquids with cross-linked smectite catalysts. 1. Effects of pillaring materials and recycling

To determine their potential for upgrading coal liquefaction products, a range of clays pillared with aluminium, aluminofluoride, titanium, cerium, vanadium, tin, chromium and zirconium species have been synthesized and reacted with Australian brown coal (Yallourn) liquefaction products in the presence of a conventional sulphided nickel molybdenum catalyst. Typically, 13% of the recycle solvent comprising an oil-vacuum bottom mixture was cracked to gas by these catalysts, so that the conversion to liquid products was lower than those obtained from initial liquefaction. However, the liquid products are comparatively more volatile. A synergistic effect between pillared clay and nickel molybdenum catalyst has been identified. Although yields of oil were similar, the product oil contained less aromatic carbon when prepared in the presence of aluminium pillared clay and nickel molybdenum catalyst than when prepared using nickel molybdenum and pillared clay catalyst in sequence. Catalysts pillared with vanadium, titanium, cerium, fluorine or phosphorus based materials improve the hydrogen content and decrease the aromaticity of the product compared with uncatalysed experiments. However, in experiments in which the catalyst was recycled, there was a marked deterioration in yields and volatility of the product.