초록 ▼

A catalyzed hydrocarbon trap material washcoat (20) used in a trap (10), which may be placed downstream of a conventional catalyst member (28), is useful for treating internal combustion engine (22) exhaust. Trap (10) traps hydrocarbons during cold operation periods and releases them for oxidation d

A catalyzed hydrocarbon trap material washcoat (20) used in a trap (10), which may be placed downstream of a conventional catalyst member (28), is useful for treating internal combustion engine (22) exhaust. Trap (10) traps hydrocarbons during cold operation periods and releases them for oxidation during higher-temperature operating periods. The material comprises palladium and silver dispersed on a high surface area metal oxide support and a zeolite material such as one or more of ZSM-5, Beta, Y, and other suitable zeolites. The trap material is efficiently made by combining in a single vessel the zeolite, the metal oxide support, and aqueous solutions of a palladium compound and a silver compound. Surprisingly, the intimate combination of silver with the palladium does not adversely affect catalytic efficiency of the palladium and provides advantageous results in enhancing catalytic oxidation of hydrocarbons desorbed from the trap (10) and coke which forms thereon.

대표청구항 ▼

[ What is claimed is:] [1.] A catalyzed hydrocarbon trap material comprising a mixture of (1) a particulate refractory inorganic oxide support having dispersed thereon a silver component and a catalytically effective amount of a palladium component, and (2) a particulate zeolite having a Si to Al at

[ What is claimed is:] [1.] A catalyzed hydrocarbon trap material comprising a mixture of (1) a particulate refractory inorganic oxide support having dispersed thereon a silver component and a catalytically effective amount of a palladium component, and (2) a particulate zeolite having a Si to Al atomic ratio of at least 10 and a pore aperture diameter of at least 4 Angstroms, the zeolite having dispersed thereon a silver component and a palladium component, the catalyzed hydrocarbon trap material being made by a process ofa) combining (i) water, (ii) a water-soluble silver component, (iii) a water-soluble palladium component, (iv) particulate refractory inorganic oxide solids, and (v) particulate zeolite solids to form an aqueous slurry of the solids;b) maintaining the resulting slurry for a time sufficient to disperse at least some of the palladium component and at least some of the silver component onto each of the inorganic oxide solids and the zeolite solids; andc) dewatering the slurry to provide dewatered solids and heating the dewatered solids to provide the catalyzed hydrocarbon trap material as a dried mixture of solids.