EFFECT OF MILD CHEMICAL PRETREATMENT ON LIQUEFACTION REACTIVITY OF ARGONNE COALS

Mild pretreatment of four coals from the Argonne Premium Coal Sample Bank using alkylalcohols and hydrochloric acid has been investigated as a method for improving liquefaction reactivity. Our technique mildly alkylates the coal (< 0.5 alkyl groups added/100 carbon atoms) and adds small amounts of chlorine which may act as a dissolution catalyst. Infrared spectroscopic studies of the treated and untreated coals indicated that alkylation occurred at phenolic and carboxylic sites within the coal, but no evidence of alkylation at carbon sites was noted. Mild pretreatment with methanol or propanol and HCl improved liquefaction reactivity for each coal studied over a range of reaction severity and conversion levels. The enhancement was far greater per unit of methyl group addition than achieved using either Sternberg's reductive alkylation or Liotta's oxygen alkylation techniques.