Shengli lignite liquefaction under syngas and complex solvent

The liquefaction of Shengli lignite (SL) were studied in the system of syngas (H₂+CO) and complex solvent (H₂O+THN) and the system of hydrogen (H₂) and tetralin (THN). Asphaltene (AS) and preasphaltene (PA) from the two systems were characterized by FT-IR. The results show that both conversion and oil yield of Shengli lignite liquefaction in the (H₂+CO)/(H₂O+THN) system are significantly higher than those in the H₂/THN system. The conversion and oil yield under syngas (H₂:CO=1:1) and complex solvent (THN:H₂O=1:1) reach respectively 88.79% and 55.47% at 400℃, 4MPa and 30min. The differences in the conversion and oil yield between the (H₂+CO)/(H₂O+THN) and H₂/THN systems are 8.00% and 7.54%, respectively. This suggests that the water-gas shift reaction can produce active hydrogen in the (H₂+CO)/(H₂O+THN) system, which benefits the hydrogenation of SL and PA. Meanwhile, THN can stabilize the free radicals from SL pyrolysis and dissolve the products (AS and PA) from SL liquefaction. The synergistic effect of two factors results in the improvement of conversion and oil yield. This study shows that it is a new lignite liquefaction technology using the (H₂+CO)/(H₂O+THN) system.