摘要
本文以宜兴堇青石为载体,γAl2O3为洗涂层,稀土元素La和Ce以不同比例负载在氧化铝上,然后再负载Pd,制得不同镧铈比的PdTWC,评价了此类催化剂对CO、HC和NOx的催化活性,并使用XRD、XPS和SEM等手段对催化剂进行表征。结果表明,PdTWC的三效性能随镧铈比的不同而变化,当m(La)∶m(Ce)=1∶4时,催化活性最好,此时Ce以3+、4+价态共存,其中Ce4+所占比例为60%。La、Ce虽然是性质相近的稀土元素,但它们在提高PdTWC活性上存在某种协同效应。
Using cordierite monoliths coated with alumina washcoat as carrier, Pd TWC with different La and Ce ratio have been prepared by impregnating aqueous La(NO 3) 3, Ce(NO 3) 3 and Pd(NO 3) 3 on the washcoat. These catalysts have been studied with respect to their catalytic activity in the purification of automotive exhaust. The means of XRD, SEM, XPS and BET were also used to characterize the catalysts. It is shown that in the catalytic assessment: the catalyst activity of Pd TWC in purifying CO, HC, NO x containing in exhaust varies with the ratio of La Ce, the best catalytic activity has been gotten when the ratio was 1∶4. Under these conditions, Ce 4+ coexisted with Ce 3+ , and the relative amount of Ce 4+ is 60%. It has also been found that there is a definite synergic action existing between La and Ce, which can improve the catalytic activity of Pd TWC.
出处
《现代化工》
CAS
CSCD
2000年第2期35-37,共3页
Modern Chemical Industry
