Composition of liquid products from catalytic hydrotreatment of flash pyrolysis tars: 2. Slurry-phase reactor products

Abstract

The compositions of the oils obtained by catalytic hydrotreatment of flash pyrolysis tars in a slurry-phase reactor using red mud as catalyst were determined by g.c. The tars were from Millmerran subbituminous and Piercefield bituminous coals. In both cases the major components of the oils produced at 460 °C were simple phenols, alkyl-substituted naphthalenes, polycyclic aromatic hydrocarbons and n-alkanes (C 6–C 30). The effect of processing temperature in the range 419–460 °C was determined for the subbituminous coal. The increased volatility of the 460 °C product was accompanied by increased concentrations of simple phenols and aromatics, including the polycyclic aromatics, and a decrease in the relative proportions of longer-chain n-alkanes, owing to increased gas formation. Comparison of the product compositions with those from a two-stage trickle-bed reactor shows that the slurry-phase products are characterized by: 1. (1)alkylphenols (as opposed to alkylcyclohexanes for the trickle-bed products) as the major single-ring products; 2. (2)alkylnaphthalenes (as opposed to alkyltetralins) as the major two-ring products; 3. (3)higher concentrations of polycyclic aromatic hydrocarbons; and 4. (4) lower concentrations of n-alkanes. Hydrocracking of product oils would be necessary to reduce aromaticity.