Identification of Mono Methyl-Dibenzothiophenes in Coal Liquefaction Products

摘要

Previous work has involved investigations into the effects of H sub 2 S on the liquefaction of low-rank coal. Addition of H sub 2 S to the process, increases the yield and improves the quality of distillable oils, but may be incorporated into the product oil. We are therefore interested in the detection and identification of sulfur compounds in liquefaction products; especially as this pertains to sulfur incorporation. The liquefaction process is typically conducted in the presence of a hydrogen donor solvent. The samples analyzed in this work were portions of the products of two runs which employed two distinctly different startup solvents. Authentic samples of the four isomeric methyldibenzothiophenes were synthesized according to published procedures and characterized by correlation of exp 1 H NMR chemical shifts. exp 13 C NMR and mass spectroscopy were used for further characterization. Dibenzothiophene and the methyldibenzothiophenes in the samples from Runs 101 and 103 were initially identified by GC/MS. Unfortunately, the individual isomers could not be distinguished, since each exhibited the same fragmentation pattern. The isomers were subsequently identified by matching their GC retention times with those of the authentic samples. Analysis of the PDU startup solvent (Run 103) showed that these sulfur compounds were present; therefore we are unable to conclude whether any sulfur incorporation had occurred. We can conclude, however, that sulfur incorporation occurred in Run 101 since analysis of startup solvent A04 indicated that sulfur compounds were not present initially. 6 references. (ERA citation 09:017943)