GB784229A - Improvements in or relating to a method of regenerating a platinum-alumina catalyst - Google Patents

Abstract

Non-fluoride-containing platinum-alumina reforming catalyst prepared according to Specification 735,390 is regenerated by burning off carbonaceous material with a mixture of inert gases and not more than 1.5 per cent by volume of free oxygen at 500-930 DEG F. and a pressure not exceeding 500 p.s.i.g. while keeping the water vapour partial pressure of the exit gases below 50 mm. of mercury, then oxidizing the platinum by maintaining the catalyst at 800-950 DEG F. in a dry atmosphere having a partial pressure of free oxygen of 0.2-3 atmospheres for at least 0.5 hour, and reducing the oxidized platinum to the metallic state. The catalyst may be in the form of a fixed, moving, or fluidized bed; with a plurality of reactors, one reactor may be regenerated at a time. After the reforming period the catalyst is cooled and purged of combustible gas, e.g. by reducing the heat to the process and stopping the hydrocarbon feed while continuing to recycle gas; the pressure may then be reduced to a partial vacuum and the catalyst purged with flue gas or other inert gas. The pressure is then increased, e.g. to 100-150 p.s.i.g., and air is added to the inert gas which is dried and recirculated. The temperature and oxygen content of the gas are controlled to give the desired burning temperature. The second oxidation stage may be carried out at 930-950 DEG F. for 5-30 hours; the required oxygen partial pressure is preferably attained by compressing dry air. After completing the oxidation, the catalyst is cooled and reduced with a hydrogen-containing gas, e.g. at 40 p.s.i.g. In examples, catalysts prepared according to Example V of Specification 735,390 are regenerated. The first burning stage is carried out (a) with nitrogen containing 1 or 1.5 per cent oxygen at atmospheric pressure; (b) with nitrogen containing 0.35 per cent oxygen at a total pressure of 400 p.s.i.g.; or (c) with nitrogen containing 0.7 per cent oxygen at 30 p.s.i.g. increasing to 130 p.s.i.g. The second oxidation stage is carried out (a) with undiluted air at atmospheric pressure; (b) with pure dry oxygen at 20 p.s.i.g.; or (c) with air at 130 or 150 p.s.i.g. Reference has been directed by the Comptroller to Specifications 735,145 and 748,777.