Removal of ultra- fine particles from a Fischer Tropsch stream

This invention relates to a process for the removal of catalyst particles from a hydrocarbon stream (14) derived from the reaction of synthesis gas (12) with a particulate Fischer Tropsch catalyst in a Fischer Tropsch reactor (10). The process includes a primary separation step (16) which makes use of a filter, wherein the filter has a pore size which is 70% to 95 of the average size of the particles of the Fischer Tropsch catalyst, thereby forming a primary filtered hydrocarbon stream (18) containing fine catalyst particles. The benefit of this selection of filter pore size is that it mitigates fines build-up on the filter of the primary separator. The primary filtered hydrocarbon stream(18) is then passed to a secondary separation step in a cross-flow filtration unit (20) which removes fine catalyst particles from the primary filtered hydrocarbon stream to provide a retenate (24) containing the catalyst fines, and permeate (22) containing a hydrocarbon product.