Patent ID: 7968610

Claim:
A process for maintaining the stability of the performances of a catalyst for Fischer-Tropsch reaction carried out in a slurry bubble column reactor, wherein a solid phase, consisting of a metal cobalt-based catalyst in finely subdivided form, is dispersed in a continuous liquid phase consisting of hydrocarbons, and is kept in suspension by a gaseous phase consisting of synthesis gas, which passes through said liquid phase, in the form of bubbles, comprising: a. in the reaction start-up phase, regulating the operative variables, among which, prevalently, the flow-rate of the synthesis gas, so that the P H2O /P H2 ratio between the partial water pressure (P H2O ) generated during the reaction, and the partial hydrogen pressure (P H2 ) gradually increases from 0.4 to 0.8 (without substantially exceeding these limits) for a period of time not shorter than 100-150 hrs and not longer than 200-300 hrs; b. in the reaction start-up phase, regulating the operative variables, among which, prevalently, the flow-rate of the synthesis gas, so that the P H2O /Z ratio gradually increases from 0.4 to 0.8 (without substantially exceeding these limits) for a period of time not shorter than 100-150 hrs and not longer than 200-300 hrs, wherein Z is given by the following equation: Z=P 0 ·( T/T 1 ) 4 ·e −(K2/t·K3)) wherein P 0 =1 bar T 1 =100° C. T=temperature inside the reactor, in ° C. K2=constant equal to 7745 K·nm t=temperature inside the reactor as K K3=average diameter of the catalyst pores; and c. at the end of the start up, maintaining the P H2O /P H2 and P H2O /Z ratios substantially the same as, or lower than 0.8, by operating on the same operative parameters of the two phases previously described.