The hydrodeoxygenation, hydrogenation, hydrodealkylation and ring-opening reaction in the hydrotreating of low temperature coal tar over Ni–Mo/γ-Al2O3 catalyst

Abstract

The hydrotreatment of low temperature coal tar was carried out in a fixed bed reactor with the Ni–Mo/γ-Al2O3 catalyst. The compounds in the product and feedstock were determined by GC–MS and the effect of temperature, pressure and liquid hourly space velocity (LHSV) were studied based on this analysis. The results show that high temperature had adverse effect on the hydrogenation of aromatics but favorable effect on the ring-opening reaction and hydrodealkylation of aromatics. High pressure and low LHSV was very positive for all these three kinds of reaction of aromatics in coal tar. Most of the aromatics in the products of gasoline originate from the conversion of the monocyclic O-containing compounds. The reactivity of coal tar hydrocracking with the Ni–Mo/γ-Al2O3 catalyst is not very high because γ-Al2O3 is weak acid carrier. The ring-opening seldom occurs at temperatures lower than 380°C. Hydrodeoxygenation is the most important reaction to the upgrading of the coal tar. The gasoline fraction in the product mainly comes from the phenol hydrodeoxygenation in the coal tar hydrogenation process.