Infrared spectroscopic study of coal depolymerization catalysis by metal chlorides

Abstract

Diffuse reflectance infrared spectroscopy was used to monitor in situ reactions in which ether linkages undergo cleavage during the depolymerization of metal chloride impregnated Wyodak coal at elevated temperature. Subtraction procedures were used to obtain difference spectra that reveal small net changes in the IR band intensity between 2000 and 1000 cm −1 . Phenyl ethers of the form Ph-O-CH 2 -R are cleaved catalytically by metal chloride, and the oxygen is retained as a phenolic group. Both the FeCl 3 and CrCl 3 catalysts have a higher reactivity and selectivity for the cleavage of ether linkages than does the ZnCl 2 catalyst. A higher degree of catalytic cleavage of phenyl ether is obtained when the ZnCl 2 -impregnated coal is prepared in methanol as compared to samples prepared in water and acetone