Catalytic Steam Gasification of Liquefaction Residue

Abstract

Steam gasification of liquefaction residue was carried out in a thermo-balance. The chemical structure of Fe liquefaction catalyst in residue during gasification was investigated with XRD. Fe catalyst was contained in residue as FeS, transformed to Fe₃O₄ in the steam gasification stage and then to Fe₂O₃ after burning. Fe catalyst contained in residue showed small catalytic activity for the steam gasification of residue, however, the reactivity of the char produced from liquefaction residue was quite lower than that of raw coal char.
In order to develop an effective gasification process of liquefaction residue, Ca catalyst and K catalyst were added to the residue. The catalysts added enhanced the steam gasification rate of residue. The effectiveness of the catalyst depended on the method of catalyst addition, the catalyst type and the catalyst loading. The catalytic effect of Ca catalyst prepared from lime milk was larger than that of K₂CO₃ catalyst in the range of less than 10wt% of catalyst loading, while the gasification rate of the sample with 20wt% of potassium was significantly higher than that of the sample with 20wt% of calcium.
Highly dispersed Ca catalyst was also quite effective for SO2 removal during char combustion.