In situ hydrocarbon conversion catalyst regeneration and sulfur

Abstract

A method is disclosed for regenerating reforming catalysts containing a platinum group component and/or rhenium component in association with a halogen component on a porous inorganic oxide, such as one containing alumina without significant displacement of the rhenium components by sulfur oxides generated during the regeneration process. The method is particularly characterized in that carbon is removed from the catalyst by in situ oxidation at temperatures not in excess of about 750.degree. F. and without modification of the catalytic reforming process flow circuit, as by disconnecting or isolating the heat exchangers and furnace tubes. Sulfide scale is converted in a separate oxidation step to sulfur dioxide, SO.sub.2, without substantial oxidation to sulfur trioxide, SO.sub.3, by maintaining the inner walls of the heat exchangers and furnace tubes, where such iron sulfides are present, at a temperature not in excess of about 900.degree. F. and not less than about 750.degree. F. and under regenerating conditions including a low oxygen, O.sub.2, concentration. The sulfur dioxide then passes through the reforming catalyst without effectively displacing rhenium components from the carrier base. Further, by removal of these sulfides, complete regeneration of the catalyst is facilitated for subsequent redistribution of the platinum component at temperatures in excess of 900.degree. F., particularly when accompanied by halide addition.