Product compositions in rapid hydropyrolysis of coal

Abstract

The rapid hydropyrolysis of a Montana lignite and a Pittsburgh Seam bituminous coal has been examined at a high heating rate (1000 °C s −1). The results are interpreted in the light of those presented previously for pyrolysis of the two coals. A complex situation involving simultaneous chemical and mass transfer rate control is revealed, and it is apparent that the pyrolysis phase cannot be treated separately from the hydropyrolysis phase. Three key process variables, hydrogen pressure, temperature, and particle diameter, are seen to have major effects on the total yields of products. There appears to be an important tradeoff between high hydrogen pressures and high temperatures. Under the present conditions of almost zero vapour residence time at elevated temperatures, methane is the principal product of reaction between hydrogen and coal, and the yields of light aromatic liquids are small.