Tacoma filtrate

Hydrotreating of Tacoma filtrate was investigated over both an inert, low-surface-area alumina and a silica-promoted cobalt-molybdena (Co-Mo) on alumina catalyst. The filtrate feed used in this study was from a run made at Tacoma on June 21,1976 operating with Kentucky Colonial coal as feed at 843°F, 1500 psig at a solvent to coal ratio of 1.6 1. This... 

However, the heptane insolubility of 850° F+ SRC residue from Tacoma (see Table I) showed little change when subjected to the same treatment as the filtrate from Tacoma. The 850°F+ SRC residue received from Tacoma had 81% heptane insolubles while the 850°F+ residue from the distillation of the reconstituted SRC filtrate, which is described below, had 87% heptane insolubles. This was a 6% increase in heptane insolubles in Tacoma residual SRC after thermal treatment compared with a 40% increase for the Tacoma filtrate heptane insolubles after the same treatment. 

Table VI. Results on Tacoma Filtrate Using 850°F Cut Point for Co-Mo...

Authentic and synthetic solvent-refined coal filtrates were processed upflow in hydrogen over three different commercially available catalysts. Residual (>850°F bp) solvent-refined coal versions up to 46 wt % were observed under typical hydrotreating conditions on authentic filtrate over a cobalt-molybdenum (Co-Mo) catalyst. A synthetic filtrate comprised of creosote oil containing 52 wt % Tacoma solvent-refined coals was used for evaluating nickel-molybdenum and nickel-tungsten catalysts. Nickel-molybdenum on alumina catalyst converted more 850°F- - solvent-refined coals, consumed less hydrogen, and produced a better product distribution than nickel-tungsten on silica alumina. Net solvent make was observed from both catalysts on synthetic filtrate whereas a solvent loss was observed when authentic filtrate was hydroprocessed. Products were characterized by a number of analytical methods. 

Apparently the increase in heptane insolubles resulted from thermal repolymerization during distillation. The filtrate readily underwent this reaction but Tacoma 850° F+ SRC residue was unreactive because it already had been exposed to high temperature when isolated by distilla-... 

An 850°F cut point was used at the Tacoma plant when this filtrate was generated. 

Processing Reconstituted SRC Filtrate. A synthetic blend of 850°F+ residual SRC in a coal-derived creosote oil was prepared and used in catalyst evaluation studies when SRC filtrate became unavailable. The synthetic blend was a 52 wt % mixture of residual Tacoma 850°F+ SRC dissolved in Koppers Tar creosote oil. 

The process operates without catalysts, since the catalytic activity of the finely divided pyrites in the coal feedstock is sufficient. Hydrogen consumption is around 2%. The undissolved residue is separated by pressure filtration. A pilot plant was started up at Fort Louis in Tacoma/Wash., USA in 1974, with a throughput of 50 t/d of coal. By increasing the severity of cracking, this method can also be used to produce heavy heating oil (SRC-II process). 

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