Sasol Technology Proprietary Limited

Herman Gerhardus Nel

André Peter Steynberg

Werner Siegfried Ernst

Roy W Silverman

Jacob W De Boer

Johannes J Liebenberg

A method of operating a process for catalytically converting one or more reactants to one or more products using a fluid bed reactor containing a catalyst which deactivates over time includes, during a catalyst campaign, in a step A, gradually increasing an operating temperature of the reactor to counteract the negative effect of catalyst deactivation on a conversion rate of the one or more reactants. The operating temperature is not allowed to exceed a selected maximum operating temperature. Thereafter, in a step B, catalyst is added which has the tendency to increase the conversion rate of the one or more reactants into the reactor, and the operating temperature of the reactor is reduced to counteract to at least some extent the effect of the added catalyst on the conversion rate of the one or more reactants. The operating temperature remains above a selected minimum operating temperature during step B. Steps A and B are repeated until the end of the catalyst campaign or until the end of a production run.

Operation of processes which employ a catalyst that deactivates over time

A process () for synthesising hydrocarbons includes feeding a gaseous feedstock () comprising hydrogen and carbon monoxide, into a first Fischer-Tropsch reaction stage () which is a three-phase low temperature catalytic Fischer-Tropsch reaction stage, and allowing the hydrogen and carbon monoxide partially to react catalytically in the first reaction stage () to form hydrocarbons. At least a portion of a tail gas () which includes unreacted hydrogen and carbon monoxide obtained from the first reaction stage, is fed into a second Fischer-Tropsch reaction stage () which is a two-phase high temperature catalytic Fischer-Tropsch reaction stage. The hydrogen and carbon monoxide are allowed at least partially to react catalytically in the second reaction stage () to form gaseous hydrocarbons.

Process for synthesising hydrocarbons

A process for producing liquid and/or gaseous products from gaseous reactants includes feeding them, at a low level, into a slurry bed of particles suspended in a liquid, to react as they rise therethrough to form the products, with the reactants and any gaseous product assisting in maintaining the suspension. The liquid product forms, together with the suspension liquid, the liquid phase of the bed. Any gaseous product and unreacted reactants rise from the bed into a head space. Slurry passes downwardly in the bed through downcomers located respectively in first and second downcomer regions of the bed, thereby redistributing solid particles within the bed. The second downcomer region is spaced vertically with respect to the first downcomer region. Any gaseous product and unreacted reactants are withdrawn from the head space and liquid phase is withdrawn from the bed.

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Sasolburg, South Africa

Herman Gerhardus Nel