Date of Award


Document Type


Degree Name

Master of Science (MS)


Chemical Engineering


The effects of second stage temperature and the effects of the type of solvent used on the liquefaction of North Dakota lignite in a staged liquefaction process were investigated. The UND hot-charge, time-sample, batch autoclave facility was used for the experimentation. Approximately one hundred and fifty grams of moisture- and ash-free (MAF) lignite, three hundred grams of solvent (either anthracene oil or a hydrogenated anthracene oil was used as the solvent), and seventy five grams of water were reacted in the hot charged experiments. Carbon monoxide was used in the first stage and hydrogen and one hundred grams of solvent were added to the second stage. First stage temperature was held at about 360°C and pressure ranged from 3725 to 4645 psig. The second stage temperature was varied from 424 to 460°C while the pressure range was from 2500 to 2900 psig. Residence time was twenty minutes in the first stage and thirty minutes in the second stage.

Overall conversion ranged from 82.5 to 93.9 percent while total distillate yield varied from 12 percent to about 30 percent of MAF coal fed, with the major increase in light oils. Increasing second stage temperature increased the distillate yield significantly and increased overall conversion and hydrocarbon gas production slightly. The presence of a good hydrogen donating solvent, HA061, in both the first and second stages produced higher overall conversion and distillate yield. Two staged liquefaction using only solvent HA061 yields not only higher overall conversions and distillate yields but greatly increased the fraction of light oils and decreased the yield of THF-soluble residuum as compared with a single stage run which only saw second stage conditions.