Advanced direct coal liquefaction concepts. Quarterly report, July 1, 1993--September 30, 1993

Abstract

The bench unit was operated in the two stage configuration during this quarter, and two runs (DOE-008 and DOE-009), which included eight mass balance periods were completed. Addition of potassium carbonate, although the best catalyst for promoting the shift reaction in the first stage, led to severe plugging problems particularly between the first and second stage reactors. Therefore, sodium aluminate, less effective as a shift catalyst, but better for unit operation, was used as an alternate. Ammonium tetrathiomolybdate was used throughout as a second stage catalyst, with and without sodium aluminate as shift catalyst. Overall coal conversions under the conditions studied were approximately 80% wt on MAF coal and C{sub 1}--C{sub 4} gas yields were about 10% wt. Conditions in both stages need to be optimized to improve coal conversion and maximize distillable oil yield. The results so far indicate that increased severity and better carbon monoxide shift conversion are required in the first stage, while maximum pressure ({approximately}2,500 psi) is needed in the second stage. The effects of other catalysts also need to be determined, including the establishment of optimum conditions for operation with those catalysts. Ammonium tetrathiomolybdate was shown to possess no measurable activity as a shift catalystmore » at the level used (600 ppM on total feed) in either the bench unit or autoclave tests. However, in autoclave tests, the addition of ammonium tetrathiomolybdate did improve asphaltene and preasphaltene conversion to oils (and therefore, product quality) in both one and two stage tests when compared with iron sulfide.« less