Performance of MoCl₃-LiCl-KCl and NiCl₂-LiCl-KCl Catalysts in Coal Hydroliquefaction with a Hydrogen Donor Vehicle

The catalytic performance of MoCl₃-LiCl-KCl and NiCl₂-LiCl-KCl salts in coal hydroliquefaction with the H donor tetralin was studied. Yilan subbituminous coal impregnated with the above catalysts and with LiCl-KCl at different loading levels (weight ratios of salts to coal of 0.1-1.0) was hydroliquefied at 400 °C for 1 h with an initial H₂pressure of 4.9 MPa. Increased loading of the MoCl₃salt increased oil yield (up to 50 wt %), coal conversion, and H₂consumption, decreased the net hydrogen transfer from tetralin, and lowered the heteroatom content of oil. Addition of the NiCl₂salt below a weight ratio of 0.2 led to more pronounced increases in oil yield, coal conversion, and H₂consumption and decreases in net hydrogen transfer from tetralin than with the MoCl₃system. Higher loadings (>0.2) led to a small decrease in H₂consumption in spite of a further increase in oil yield (up to 50 wt %), implicating contributions of in situ formed H donors. The use of a LiCl-KCl mixture slightly improved coal conversion while considerably suppressing H₂consumption. The relation between coal conversion and hydrogen consumption suggests that the action of the MoCl₃and NiCl₂catalysts led to enhanced but selective hydrocracking reactions that contribute mainly to oil production. ¹H NMR analysis of the oil revealed that hydroaromatic compounds increased and the average ring sizes of aromatics decreased with increased loading of the catalysts.