Fuel-Blending Stocks from the Hydrotreatment of a Distillate Formed by Direct Coal Liquefaction

摘要

The direct liquefaction of coal in the iron-catalyzed Suplex process was evaluated as a technology complementary to Fischer-Tropsch synthesis. A distinguishing feature of the Suplex process, from other direct liquefaction processes, is the use of a combination of light- and heavy-oil fractions as the slurrying solvent. This results in a product slate with a small residue fraction, a distillateaphtha mass ratio of 6, and a 65.8 mass % yield of liquid fuel product on a dry, ash-free coal basis. The densities of the resulting naphtha (C_5-200℃) and distillate (200-400℃) fractions from the hydroprocessing of the straight-run Suplex distillate fraction were high (0.86 and 1.04 kg/L, respectively). The aromaticity of the distillate fraction was found to be typical of coal liquefaction liquids, at 60-65%, with a Ramsbottom carbon residue content of 0.38 mass %. Hydrotreatment of the distillate fraction under severe conditions (200℃, 20.3 MPa, and 0.41 g_(feed) h~(-1) g_(catalyst)~(-1)) with a NiMo/Al_2O_3 catalyst gave a product with a phenol content of < 1 ppm, a nitrogen content <200 ppm, and a sulfur content < 25 ppm. The temperature was found to be the main factor affecting diesel fraction selectivity when operating at conditions of WHSV = 0.41 g_(feed) h~(-1) g_(catalyst)~(-1) and P_(H_2) = 20.3 MPa, with excessively high temperatures (T > 420℃) leading to a decrease in diesel selectivity. The fuels produced by the hydroprocessing of the straight-run Suplex distillate fraction have properties that make them desirable as blending components, with the diesel fraction having a cetane number of 48 and a density of 0.90 kg/L. The gasoline fraction was found to have a research octane number (RON) of 66 and (N + 2A) value of 100, making it ideal as a feedstock for catalytic reforming and further blending with Fischer-Tropsch liquids.