Pyrolysis GC/MS Analysis of Low-Rank Coal

摘要

The reactivity of coals under liquefaction conditions is related to their thermal decomposition. Pyrolysis GC/MS is used to determine the identity of the volatile products as the changes in coal structure occur. A Wyoming subbituminous coal (Clovis Point) and a North Dakota lignite (Indian Head) were heated under helium at four temperatures (160 sup 0 C, 250 sup 0 C, 300 sup 0 C, and 350 sup 0 C) for 30 minutes. The volatile species were cryogenically trapped in a capillary gas chromatographic column for GC/MS analysis. The two lower temperatures showed only devolatilization products (e.g., biological markers such as alkanes and terpenoids) while the higher temperatures yielded products resulting from bond-breaking (i.e., pyrolysis). The devolatilization and pyrolysis products of the two coals were similar in overall composition but markedly different in their distribution. The subbituminous coal (Clovis Point) pyrolysate contained phenol and cresols along with large amounts of C sub 19 to C sub 31 normal alkanes. Indian Head lignite pyrolysate contained a much larger amount of phenol, alkyl substituted phenols and dihydroxybenzene and lesser amounts of C sub 19 to C sub 31 alkanes. 10 refs., 3 figs. (ERA citation 13:000062)