Abstract:
Direct coal liquefaction residue (DCLR) is deashed by hydrochloric acid and hydrofluoric acid to obtain ACLR. The ACLR was extracted with
n-hexane, toluene and tetrahydrofuran to obtain
n-hexane insoluble matter (HCLR), toluene insoluble matter (TCLR), tetrahydrofuran insoluble (FCLR). The surface properties of ACLR, HCLR, TCLR and FCLR were characterized by inverse gas chromatography (IGC). Based on net residual volume
Vn of the non-polar probe, surface dispersion free energy were calculated by Dorris-Gray and Schultz method respectively. The adsorption enthalpy △
Hsp of the polar probe on surface of the 4 insoluble solids was obtained by
Vn of the polar probe, and the acid constant
Ka and the base constant
Kb of the 4 insoluble solids were calculated by △
Hsp. The results show that the surface dispersion free energy of ACLR are obviously changed after solvent extraction, and the dispersion free energy on surface of the 4 insoluble solids is decreasing from 60 to 100℃. By
Kb/
Ka> 1 and △
Hsp analysis, 4 insoluble solids surfaces are both amphoteric and the alkaline effect is stronger than that of the acid effect. As a kinetic adsorption technique, IGC can quickly and accurately characterize change of surface properties of DCLR during fractionated extraction. At the same temperature the surface dispersion free energy obtained by the Dorris-Gray method is slightly higher than that by the Schultz method.