Hydrogenation of brown coal: 8. The effect of added promoters and water on the liquefaction of Victorian brown coal using hydrogen, carbon monoxide and synthesis gas

Abstract

Victorian brown coal has been pretreated with a wide range of additives and treated coals reacted with hydrogen, with carbon monoxide, and with synthesis gas ( H 2 + CO). Reactions were carried out both in the presence and in the absence of water. The promoters which are active in dry hydrogenation reactions (Co, Ni, Cu, Zn, Mo, Sn and Pb) lost some activity for conversion to oil when water was added to the reactions. These promoters were found to be inactive in reactions using carbon monoxide. Chromium acetate, vanadyl sulphate, magnesium acetate, sodium aluminate, and sodium silicate were promoters for reactions of coal with carbon monoxide. However, at comparable promoter loadings (300 mmol kg −1) the promoters active in carbon monoxide were not as effective as the promoters active with hydrogen. At this loading the maximum increase in conversion for the carbon monoxide promoters was ≈ 12% (over the value for acid washed coal) whereas the maximum increase in conversion for the hydrogen promoters was ≈ 25%. Reactions of the treated coals with synthesis gas generally gave values intermediate between those obtained for reactions with carbon monoxide and with hydrogen. Addition of promoters active towards reactions of hydrogen led to increased utilisation of hydrogen fro, the gas phase and a decrease in consumption of hydrogen from the solvent, tetralin. In general, addition of water led to a decrease in the utilisation of hydrogen from the solvent, tetralin.