Molten alkali metal hydroxide catalyzed coal liquefaction. Final report, October 1978-September 1979

The most important results of this research are the following: With a 2/1 NaOH melt/coal ratio, conversions of >80% and liquid yields of >50% can be achieved under hydroliquefaction conditions using tetralin. NaOH is a more effective catalyst than KOH. NaOH affords very good heteroatom removal, particularly with respect to sulfur and nitrogen. At 400/sup 0/C, some improvement in liquefaction is noted compared with the reaction at 425/sup 0/C. Contacting is very important. Preliminary experiments indicated that impregnation of small amounts (2 wt %) of NaOH has some catalytic effect and improves conversion. Inconel 671 is a satisfactory material of construction for use with NaOH under hydroliquefaction conditions. Inconel 600, 617, 625, and 671 were tested as potential materials of construction for molten alkali metal hydroxide-catalyzed coal liquefaction. Coupons were tested in both the hydroxide-sulfide melt and in the vapor phase. The samples in the melt showed little evidence of corrosion, and the samples in the vapor phase showed even less. There had been some general surface attack of the samples in the melt, but no noticeable intergranular corrosion, no stress-corrosion cracking, and no pitting. Of the four samples, Inconel 671 showed the least corrosion with an estimated corrosion rate of 2.8 mils/year.