A pulse reactor was used to compare the catalytic activity of a commercial desulphurization catalyst (Nalco 471) and of mineral matter from Western Kentucky coal. Hydrodesulphurization of thiophene, a model coal sulphur compound, was the reaction studied. Mineral matter was obtained from the coal in its least altered state by a low-temperature, oxygen-plasma technique commonly referred to as low-temperature ashing. Conversion is determined from the C4 gases which are separated in a two-column chromatographic system. At 748 K it was found that thiophene conversion with mineral matter was 12% of that with the commercial catalyst. Relative activities of hydrogenation of intermediate butenes to butane, the effect of presulphiding, and that of pyridine poisoning were also determined.
In current gasification and liquefaction processes, the naturally occurring mineral matter in the coal or lignite is present during the reaction period. No definitive studies are available which separate the catalytic effect of the inherent mineral matter and added catalysts. Yavorsky et al. ' speculated that coal mineral matter behaved as a catalyst during liquefaction of coal to oil. Some of the important reactions that occur are hydrocracking, hydrogen transfer, hydrogenation, isomerization, and hydrodesulphurization (I-IDS). The purpose of this study was to compare quantitatively the catalytic activity of a commercial HDS catalyst that has been used in coal liquefaction with that of mineral matter from a Western Kentucky coal, using a pulse reactor. The reaction chosen was the I-IDS of thiophene which serves as a model organic sulphur-coal compound.
Coal mineral matter in its least altered state was first obtained by Gluskoter' using radio-frequency low-temperature ashing. This method represented a breakthrough in coal analysis, and most of the work with low-temperature ash (LTA) has been focused in this area. By X-ray diffraction Rao and Gluskoter3 identified pyrite, calcite, quartz, and clay minerals as the principal constituents of LTA produced from 65 Illinois-basin coals. In this paper mineral matter and LTA are used synonymously.
Commercial catalysts for HDS are alumina-supported oxides of cobalt and molybdenum or nickel and molybdenum, which are sulphided in use. Two extensive reviews have recently been published detailing catalyst structure, reaction mechanisms and kinetics, and commercial applications (Schuman and Shalit4 and Schuit and Gates'). Both reviews present the reaction mechanism of Owens and Amberg whereby reaction occurs by direct hydrogenolysis of the carbon-sulphur bond forming 1,3-butadiene which quickly hydrogenates to the butene isomers which in turn