Patent ID: 6303530
Filing Date: 2001-10-16
Classification: B01J

Abstract:
A method for preparing a uniformly impregnated extrudate catalyst including a zeolite, a noble metal and a predetermined amount of sodium, which comprises:extruding a mixture which includes water, a non-zeolitic refractory inorganic binder selected from the group consisting of alumina, silica, and mixtures thereof, and a zeolite comprising as nonframework cations a major amount of ammonium and a measurable initial amount of sodium to produce an extrudate including the binder and the zeolite;drying the extrudate at less than about 500 degrees F.;impregnating a noble metal selected from the group consisting of platinum, palladium, and mixtures thereof on the extrudate by exposing the extrudate to an impregnating solution which includes: (a) an aqueous solvent; (b) a water-soluble compound containing said metal; and (c) an amount of ammonium ions which is in the range of about 0.01 to about 60 percent of the ion exchange capacity of the zeolite and, thereafter, vaporizing the solvent; andcalcining the impregnated extrudate to produce a uniformly impregnated extrudate catalyst including said metal, the binder, the zeolite, and a predetermined amount of sodium which is at least about 50 percent of the initial amount;wherein the extrudate is maintained at less than about 500 degree F. during the period from start of extruding to immediately before impregnating.