催化学报
催化學報
최화학보
CHINESE JOURNAL OF CATALYSIS
2014年
8期
1267-1280
,共14页
阳雪%杨林颜%林嗣煜%周仁贤
暘雪%楊林顏%林嗣煜%週仁賢
양설%양림안%림사욱%주인현
单钯密偶催化剂%催化性能%氧化铈%热稳定性%原位红外光谱
單鈀密偶催化劑%催化性能%氧化鈰%熱穩定性%原位紅外光譜
단파밀우최화제%최화성능%양화시%열은정성%원위홍외광보
Fourier transform spectroscopy%Catalytic behavior%Thermal stability%Palladium-only close-coupled catalyst%Appropriate ceria In situ diffuse reflectance infrared
以La改性的Al2O3为载体，采用共吸附浸渍法制备了一系列不同CeO2含量的单Pd密偶催化剂，并对其进行了表征。 PdOx和CeO2之间的强相互作用改善了Pd0再氧化为PdO的能力，同时增强了反应条件下硝酸盐，亚硝酸盐和异氰酸盐在载体上的吸附。因<br> 此适量CeO2的添加明显改善了新鲜催化剂对HC和NOx的催化性能，且当CeO2添加量为2%时催化效果最佳。 Pd-Ce界面上PdOx和CeO2间强相互作用也使得PdOx物种在高温时仍能以小颗粒的形式分散在载体上，从而显著地提高催化剂的热稳定性。经1100°C高温老化后， CeO2(2%-4%)的存在明显拓宽了HC和NOx的操作窗口，这对于提高单Pd密偶催化剂在汽车尾气处理上的催化性能有重要意义。
以La改性的Al2O3為載體，採用共吸附浸漬法製備瞭一繫列不同CeO2含量的單Pd密偶催化劑，併對其進行瞭錶徵。 PdOx和CeO2之間的彊相互作用改善瞭Pd0再氧化為PdO的能力，同時增彊瞭反應條件下硝痠鹽，亞硝痠鹽和異氰痠鹽在載體上的吸附。因<br> 此適量CeO2的添加明顯改善瞭新鮮催化劑對HC和NOx的催化性能，且噹CeO2添加量為2%時催化效果最佳。 Pd-Ce界麵上PdOx和CeO2間彊相互作用也使得PdOx物種在高溫時仍能以小顆粒的形式分散在載體上，從而顯著地提高催化劑的熱穩定性。經1100°C高溫老化後， CeO2(2%-4%)的存在明顯拓寬瞭HC和NOx的操作窗口，這對于提高單Pd密偶催化劑在汽車尾氣處理上的催化性能有重要意義。
이La개성적Al2O3위재체，채용공흡부침지법제비료일계렬불동CeO2함량적단Pd밀우최화제，병대기진행료표정。 PdOx화CeO2지간적강상호작용개선료Pd0재양화위PdO적능력，동시증강료반응조건하초산염，아초산염화이청산염재재체상적흡부。인<br> 차괄량CeO2적첨가명현개선료신선최화제대HC화NOx적최화성능，차당CeO2첨가량위2%시최화효과최가。 Pd-Ce계면상PdOx화CeO2간강상호작용야사득PdOx물충재고온시잉능이소과립적형식분산재재체상，종이현저지제고최화제적열은정성。경1100°C고온노화후， CeO2(2%-4%)적존재명현탁관료HC화NOx적조작창구，저대우제고단Pd밀우최화제재기차미기처리상적최화성능유중요의의。
A series of La-Al2O3 supported Pd-Ce close-coupled catalysts were synthesized by a co-adsorption impregnation method and subsequently investigated. In the case of fresh catalysts, the presence of an optimal concentration of ceria obviously promoted the catalytic activity during HC and NOx eliminations, owing to the interaction between the palladium oxide species (PdOx) and CeO2 that improves the oxidation of Pd0 to PdO and enhances the adsorption of nitrite/nitrates and isocyanate intermediate species on the support under reaction conditions. Pd-Ce(2.0)/La-Al2O3 catalyst (where 2.0 is the wt%of CeO2) exhibited the highest catalytic activity for HC and NO eliminations. Following aging at 1100 °C, the operational window for HC and NOx conversions was broadened and the thermal stability of the catalysts was also improved as a result of the presence of an appropriate quantity of ceria (2.0-4.0 wt%). The enhanced interactions between PdOx and CeO2 evidently led to the formation of a Pd-O-Ce system, stabilizing PdOx species with smaller particle sizes at high tem-peratures. This result is significant since it suggests a means of improving the catalytic performance of Pd-only close-coupled catalysts during automobile exhaust elimination.
