3500. -----[STANDARD OIL CO.] Hydrocarbon Synthesis. British Patent 651,559; appl. filed in United States Nov. 28, 1947, Petroleum (London), vol. 14, 1951, p. 228.

Describes method for the use and reconditioning of finely divided catalysts having high activity and selectivity and used in well-known fluid-solids technique. C deposits are removed without appreciable oxidation of the spent catalyst by reacting it in the fluidized state with an oxidizing gas at about 1,000° F. and pressure of 1 atm. under conditions of quantitative composition of oxidizing gas to form atmosphere in the regeneration zone with virtually no free O₂, and CO and CO₂ in such amounts that the ration of partial pressure of CO₂/CO equals or is less than value of the equation

where r is ratio and t temperature in F°. and the sum of the partial pressures of the CO₂ and CO is less than the value of

where S is the sum of the partial pressures. Such oxidizing gas may therefore be O₂, steam, or CO₂. Means are provided to remove heat of reaction or increase it as may be required. Inert gas may be added to permit working at higher pressure. Flue gas from the top of the regenerator is recycled to the oxidizing gas inlet of the regeneration zone in amount 2-8 times that produced in the reaction. This gas may be contacted with oxidizing gas in a separate chamber so that all O₂ is converted to C oxides or H₂O vapor before passing into the regenerator; exothermic reaction is divided.