Changes in trace element concentrations and catalyst activity during the hydrocracking of a coal extract solution

Abstract

A hydrocracking rig has been constructed which involves the passing of coal-derived liquids and hydrogen over a trickle bed packed with a nickel oxide/molybdenum oxide catalyst. The ash and trace metal levels have been measured, before and after hydrocracking, and their variation with catalyst lifetime has been assessed. Al, Ca, Fe, Mg, Mn, K, Si, Na and Ti levels have been determined by a.a.s. and considerable reductions have been observed for Fe, Mg, Mn and Ti after hydrocracking. The ash level of hydrocracked extract increases for the first 50 h and then stabilizes at about 60% of the feed level. Metal levels determined for the catalyst itself show an accumulation of all the metals under consideration, especially for the sections of the catalyst which were hottest. Overall catalytic activity is not seen to decrease markedly but the ability of the catalyst to produce lower boiling material is considerably reduced after only 25 h. Comparisons between catalyst activity and metal deposition are made.