1331. HALL, C. C., AND SMITH, S. L. Life of a Cobalt Catalyst for the Synthesis of Hydrocarbons at Atmospheric Pressure. Jour. Soc. Chem. Ind., vol. 65, 1946, pp. 128-136. Chem. Abs., vol. 40, 1946, p. 5895.

Return to Abstracts of Literature 1250-1499

Literature Abstracts

Detailed account of the experimental operation of a Co-ThO₂-MgO-kieselguhr catalyst for the synthesis of hydrocarbons from CO and H₂ and the nature of the reaction products. The catalyst employed (Co 100, ThO₂ 6, MgO 12, kieselguhr 200) was prepared by mixing simultaneously boiling solutions of Co and Th nitrates (40 gm. Co and 2.4 gm. ThO₂ per 1. and Na₂CO₃ (88 gm. Na₂CO₃ per l.) and a warm, aqueous suspension of MgO and kieselguhr. After filtering, precipitating, washing, and drying, the catalyst was reduced by passing dry electrolytic H₂ downwards through it at a rate of approximately 560 l. per hr. for 2 hr. at 390°-405° and then cooling to 150°. Synthesis gas of composition CO₃, 2.5; CO, 31.4; H₂, 63.1; and N₂, 3.0% was passed through the catalyst at 150°, raised to 175° during 12 hr. and maintained for 24 hr., then raised to 180° for a second 24-hr. period and then to 185°, which was maintained constant. The synthesis gas rate was maintained at 1 l. per gm. Co per hr. throughout. Over a period of 14 months at atmospheric pressure an average yield of 122 gm. of liquid hydrocarbons per N m.³ of inert-free synthesis gas was obtained. The composition of the liquid products remained unchanged throughout the period for a given reaction temperature. Increase in temperature caused an increase in the proportion of the gasoline fraction and a decrease in that of the wax fraction. Various methods of maintaining and restoring catalyst activity were examined, and it was concluded that maximum catalyst life is obtained by intermittent treatment with H₂ at temperatures in the synthesis range and by repetition of the original reduction process when a reaction temperature of 195° becomes necessary to maintain activity. By adhering to such a procedure it is estimated that with an active catalyst and a S-free gas (not more than 0.1 gm. S per 100 N m.³) it should be possible to maintain in a single-stage synthesis an output of 115-120 gm. of liquid hydrocarbons per N m.³inert-free gas for 5-6 mo. without repetition of the reduction process and for at least 18 mo. before remanufacture of the catalyst becomes necessary. The experiments indicated the existence of 3 processes leading to the deterioration of the catalyst apart from S poisoning; the relatively rapid deposition on the catalyst of hydrocarbons readily removeable by the H₂ treatment; a change, possibly oxidation of the Co, which takes place more slowly and can be reversed by repetition of the original reduction procedure; and a still more gradual but more fundamental change, probably a physical alteration of the active surface of the catalyst or of the presence of some substance strongly absorbed on the active centers.