HYDROGENOLYTIC ACTIVITY OF SOLUBLE AND SOLID FE-BASED CATALYSTS AS RELATED TO COAL-LIQUEFACTION EFFICIENCY

A comparative activity study of soluble and solid Fe-containing cataly sts for hydrogenolysis of (1) coal-simulating compounds, i.e., 2-isopr opylnaphthalene (IPN), 1,2-dinapthylethane (DNE), and diphenylmethane (DPM), and (2) a Blind Canyon coal sample (designated as DECS-17) was performed. The soluble catalysts were supported on inert SiO2 and incl uded aqua complexes of various Fe salts, i.e., sulfate, acetate, and c hloride. The solid catalysts consisted of finely dispersed superacides , i.e., Fe2O3/SO42- and ZrO2/SO42-. The activity of the soluble cataly sts is ascribed to the aqua complex ion [Fe(H2O)(6)](3+), which is per formed or formed in situ in the presence of water and could act as a p rotonic acid by ligand dissociation. Kinetic rate constants for hydrod ealkylation of IPN and hydrogenolytic cleavage of DPM show that at tem peratures of 350-400 degrees C the above solid superacids possess mark edly higher activity as compared with that of the SiO2-supported solub le Fe salts. In agreement with this finding, the same solid superacids were found to be effective hydrogenolysis catalysts in the low-temper ature depolymerization-liquefaction of the Blind Canyon coal sample. C onsequently, small amounts (0.1-0.5 wt %) of Fe-containing solid super acids can be conveniently used in the initial step of a modified versi on of the HT-BCD (mild hydrotreatment-base catalyzed depolymerization) coal liquefaction procedure.