Pilot-plant study of upgrading of medium and low-temperature coal tar to clean liquid fuels

Abstract

Clean liquid fuels can be obtained from hydrogenation of middle and low-temperature coal tar at hydrogen pressure of 10MPa using three serial fixed-bed reactors on a pilot scale. The hydrodemetallizaiton catalyst in the first-stage reactor provides the high capacity of metal removal and asphaltenes conversion as well as the low removal of sulfur and nitrogen, protecting the highly active downstream catalysts from poisoning by carbon and metal deposition. The second-stage hydrotreating catalysts exhibited the high activity for the deep removal of sulfur and nitrogen, which was affected by reaction temperature and liquid hourly space velocity. The excellent hydrocracking activity can be obtained with a desirable distribution of liquid products under the feed nitrogen of below 100 ppm and optimized conditions. The product composition is also correlated with the reaction behaviors occurred on the different catalyst surface. The results of this work show that the whole-fraction MLTCT could be upgraded through moderate-pressure hydrogenation to produce high-quality clean fuels.