HYDROPYROLYSIS OF COAL IN A POWDER PARTICLE FLUIDIZED-BED

Coal was pyrolysed in hydrogen in a powder-particle fluidized bed at atmospheric pressure. The coal powder was continuously fed into the bed, in which CoMo/Al2O3 catalyst particles or silica sand particles were fluidized. The effect of silica sand on the secondary reactions of volatile matter was quite small, whereas CoMo/Al2O3 showed high activity for the cracking of tarry materials. In the presence of CoMo/Al2O3 a hydrocarbon liquid with a narrow product distribution was obtained; the main components were light aromatic hydrocarbons such as BTX and naphthalene. The product composition was quite sensitive to the pyrolysis temperature. The yields of light aromatic hydrocarbons with CoMo/Al2O3 increased with temperature to 590-degrees-C and then sharply decreased above 600-degrees-C. Maximum yields of light aromatic hydrocarbons, 7.2 wt% (BTX 5.8 wt%, naphthalene 1.4 wt%), approximately 30 times those with silica sand, were obtained at 590-degrees-C with a bed height of 10 cm. The yields of hydrocarbon gases increased with temperature; the CH4 yield was 32 wt% at 650-degrees-C.