Hydropyrolysis of coal in a powder-particle fluidized bed

Abstract

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 Al 2O 3 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 Al 2O 3 showed high activity for the cracking of tarry materials. In the presence of CoMo Al 2O 3 , 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 Al 2O 3 increased with temperature to 590 °C and then sharply decreased above 600 °C. Maximum yields of light aromatic hydrocarbons, 7.2wt% (BTX 5.8 wt%, naphthalene 1.4 wt%), ~30 times those with silica sand, were obtained at 590 °C with a bed height of 10 cm. The yields of hydrocarbon gases increased with temperature; the CH 4 yield was 32 wt% at 650 °C.