SOLUBILIZATION OF LIGNITE WITH SUPERACID (TRIFLUOROMETHANESULFONIC ACID) ISOPENTANE AT THE MILD CONDITIONS

Trifluoromethanesulfonic acid (TFMS) was found to solubilize lignite a nd subbituminous coal in the presence of isopentane at temperature as low as 150 degrees C for three hours under autogeneous pressure of 6.1 -6.9 MPa without hydrogen. Yallourn coal gave 63 wt% pyridine soluble fraction after reaction and required more TFMS to achieve the maximum solubility, but the treated Taiheiyo coal could be solubilized in pyri dine to the extent of 90% by the same reaction with TFMS, Acid-catalyz ed depolymerization with TFMS would be inadequate, because the lignite has many oxygen containing functional groups, The average molecular w eight of benzene soluble and THF soluble fraction from the treated Yal lourn coal decreased, and their aromaticity increased with the increas e of TFMS concentration. In contrast, average molecular weight of solu ble fraction from the treated Taiheiyo coal was unchanged, and their a romaticity decreased with the increase of TFMS concentration. It is su ggested that TFMS plays an important role in depolymerization of the c oal molecules for Yallourn coal solubilization, and accelerates alkyla tion and hydrogenation in the Taiheiyo coal solubilization. Oxygen fun ctional groups would lower the activity of TFMS as acid catalyst by in teraction, leading to the formation of water from the cleavage of alip hatic ether groups and the dehydration of phenoxy OH groups.