失效的铂/陶质催化剂中铂的细化

Redispersion of Platinum on Aged Supported Ceramic Catalysts

铂催化剂在长时间高温使用中,铂粒聚集、表面积炭、载体比表面积减少、催化活性降低.本文研究柴油机排气净化铂陶质催化剂聚集了的铂粒细化的方法,目的在恢复催化活性、延长其使用寿命.试验表明催化剂在除去表面积炭后,在纯氧气氛中于500℃下处理16～96h时,载体结构虽未恢复,但由于在催化剂表面发生金属迁移,铂晶粒明显细化,催化活性因此得到恢复,但不能恢复到新鲜催化剂的铂粒大小和活性.

During prolonged use at high temperatures, the activated platinum crystallites on supported metal catalysts can aggregate, carbon is seriously deposited on the surface of catalysts, and the surface area of support decreased rapidly. And thus the supported catalysts will lose their activity gradually. A method of redispersion of supported ceramic platinum catalysts for the purify of diesel engine exhaust gases is investigated. It is expected to restore the catalytic activity and prolong the lifetime of the catalysts. The experimental results show that although the structure of the support has not been restored yet by the treatment of catalysts in oxygen atmosphere at 500℃ for 16～96h and elimination of carbon deposited on the surface of catalysts, the platinum crystallites, by migrating on the surface, redisperse apparently, and the activity of catalysts can be restored. But the original sizes and activity of platinum particles can not be obtained. The mechanisms of redispersion has also been discussed summarily.