Deep Hydrotreatment of Coal-Derived Liquid by Denitrogenation Pretreatment

The combination of denitrogenation pretreatment and deep hydrotreatment was examined to produce clean transportation fuel from nitrogen-rich coal liquid. Heavier fraction (recovery yield; 13.1 wt%) of coal liquid was separated by distillation and denitrogenated by extractions with CuCl2 <middle dot> 2H(2)O, sulfuric acid, furfural and their combinations. Effectiveness of the treatments for nitrogen reduction was increased as following; H2SO4 (48.0%) < CuCl2 & sdot; 2H(2)O (75.0%) < furfural (80.0%) < H2SO4/furfural (85.0%) < CuCl2 & sdot; 2H(2)O/furfural (92.0%). The hydrotreatment tests using a batch-type autoclave showed that the hydrodenitrogenation of the heavier oil was promoted by the denitrogenation pretreatment with an order of furfural < H2SO4 < CuCl2 & sdot; 2H(2)O < H2SO4/furfural < CuCl2 & sdot; 2H(2)O/furfural. The combined treatment with CuCl2<middle dot>2H(2)O and furfural was the most effective for both its nitrogen reduction and enhancement of the following hydrodenitrogenation. As a result, the first-order hydrodenitrogenation rate increased by 4.4, and the nitrogen content was reduced to 11 wtppm or 230-fold compared with those of the untreated heavier oil. Mixtures of refined heavier oils and heavier-cut coal liquid were also hydrotreated and similar tendencies were obtained.