High pressure hydropyrolysis of coals by using a continuous free-fall reactor☆

Rapid hydropyrolysis of coal was carried out at temperatures ranging from 923 to 1123 K and H2 pressures up to 7 MPa by using a continuous free-fall pyrolyzer. The effects of the reaction conditions on product yields were investigated. Carbon mass balance was fairly good. It was revealed that a large amount of methane was produced due to the hydrogenolysis of higher hydrocarbons and the hydrogasification of char. The influence of pyrolysis temperature was significant on both reactions while H2 pressure mainly affected the latter. A considerable amount of reactive carbon was formed during hydropyrolysis of coal. It was converted to methane at high temperatures and high H2 pressures, while the hydrogasification of reactive carbon takes place relatively slowly at low temperatures and low H2 pressures, resulting in a low overall carbon conversion. The coal conversions observed in the present study were much higher than those obtained with using reactors where the contact between coal particles and H2 is insufficient.