Abstract: Fresh catalyst particles are added to a slurry hydrocarbon synthesis reactor and their activity increased by contact with hydrogen in-situ in the slurry in a catalyst activity increasing means, while the reactor is producing hydrocarbons. The means may be a simple, vertically oriented and hollow tube, open at the top and bottom, into which slurry and a hydrogen treat gas are passed. The treat gas acts as a lift gas which provides slurry circulation into and out of the means and back into the slurry body, while increasing the activity of the catalyst particles. During the activity increase of the fresh catalyst, partially and reversibly activated catalyst particles are rejuvenated. The activity increasing means may be inside the reactor and at least partially immersed in the slurry or external of the reactor, or both.

Abstract: Fresh catalyst particles are added to a slurry hydrocarbon synthesis reactor and their activity increased by contact with hydrogen in-situ in the slurry in a catalyst activity increasing means, while the reactor is producing hydrocarbons. The means may be a simple, vertically oriented and hollow tube, open at the top and bottom, into which slurry and a hydrogen treat gas are passed. The treat gas acts as a lift gas which provides slurry circulation into and out of the means and back into the slurry body, while increasing the activity of the catalyst particles. During the activity increase of the fresh catalyst, partially and reversibly activated catalyst particles are rejuvenated. The activity increasing means may be inside the reactor and at least partially immersed in the slurry or external of the reactor, or both.