A NEW COAL FLASH PYROLYSIS METHOD UTILIZING EFFECTIVE RADICAL TRANSFER FROM SOLVENT TO COAL

A new coal flash pyrolysis method was developed for drastically increasing the total volatile matter and the liquid products under mild conditions. The original idea of this method lies in the realization of effective hydrogen transfer from the hydrogen donor solvent to the coal fragments during the flash pyrolysis. To realize it, we found the contact at the molecular level between the solvent and the coal functional groups was essential in addition to the matching of the dehydrogenation rate of the solvent and the primary decomposition rate of coal. Contact at the molecular level was achieved by swelling the coal with solvent at 100-250-degrees-C under a pressurized atmosphere (1 MPa). When two coals were swollen by tetralin, tetralin penetrated into the micropores of its molecular size by enlarging the pores. Pyrolyzing the swollen coal in a Curie-point pyrolyzer at 670, 764, and 920-degrees-C in a helium stream at atmospheric pressure resulted in production of 56% of volatile matter for Taiheiyo (TC, Japanese subbituminous coal) and surprisingly 67% for Morwell (MW, Australian brown coal). A maximum liquid yield from MW reached more than 42%, which was larger by 24% than that from the raw coal. It was clarified that this significant increase was brought about by a physical effect as well as the effective hydrogen transfer from/via tetralin.