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 temperatures. Subtraction procedures were used to obtain difference spectra that reveal small net changes in the IR band intensity between 2000 and 1000 cm-1. The spectra suggest that the ZnCl2-impregnated coal samples could be depolymerized in an inert argon atmosphere. However, the extent to which the ZnCl2-catalyzed ether linkages are cleaved under an inert atmosphere is only about 30% of that for a high-pressure hydrogen atmosphere (68 atm). Phenyl ethers of the form Ph-O-CH2-R are cleaved catalytically by metal chloride, and the oxygen is retained as a phenolic group. Both the FeCl3and CrCl3catalysts have a higher reactivity and selectivity for the cleavage of ether linkages than does the ZnCl2catalyst. A higher degree of catalytic cleavage of phenyl ether is obtained when the ZnCl2-impregnated coal is prepared in methanol as compared to samples prepared in water and acetone.
All Science Journal Classification (ASJC) codes
- 化學工程 (全部)