Hydrocracking of hydropyrolysis tar with hydrous titanium oxide catalysts

Abstract

Vapour and liquid phase hydrocracking tests have been carried out on hydropyrolysis tar using a commercially available Ni Mo on alumina catalyst and hydrous titanium oxide (HTO) catalysts exchanged with Ni, Co, Mo and Pd. Batch screening (liquid phase) tests on condensed tar suggested that the activities of the alumina and HTO catalysts were comparable although no attempt was made to optimise conversions. Tar vapours were hydrocracked in the second stage of a fixed-bed two-stage hydropyrolysis reactor. At 400 °C and 150 bar, this converted the primary tar (≈25% of bituminous coal) into colourless liquids low in heteroatoms and containing up to 40% material boiling below 150 °C. A lower boiling product was obtained with the Co/Ni/Mo HTO formulation than with the commercial Ni Mo catalyst. The most extensively hydrogenated product was obtained with Pd HTO, which was still effective at 300 °C and 50 bar. The initial effects of carbon build-up on product composition are similar for the alumina- and HTO- Ni Mo catalysts tested.