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采用等体积浸渍法制备了一系列不同n(Cr)∶n(Ce)的Cr-Ce/H-MOR催化剂。利用XRD、H2-TPR和NH3-TPD等对催化剂结构和性质进行表征。结果表明:催化剂表面存在铬铈氧化物;催化剂在100~600℃范围内出现耗氢峰和NH3脱附峰,说明具有一定的氧化性和酸性。利用固定床连续反应器装置,在15 000 h-1的空速下,评价了所制催化剂对氧化降解三氯乙烯(TCE)的催化活性。结果表明,n(Cr)∶n(Ce)=1∶1时的催化剂(1Cr-1Ce/H-MOR)具有最优的催化活性,在279.4℃时对三氯乙烯转化率达90%。稳定性实验表明:反应400 min后,该催化剂上TCE转化率下降了9.2%。采用XRD、TG和XPS对反应前后的1Cr-1Ce/H-MOR催化剂进行表征,结果表明:催化剂结构没有发生改变,表面也无明显积炭现象;其催化活性下降可能是由n(Cr6+)和n(Ce3+)比例下降及催化剂表面吸附Cl物种引起的。
A series of Cr-Ce / H-MOR catalysts with different n (Cr): n (Ce) were prepared by the same volume impregnation method. The structure and properties of the catalysts were characterized by XRD, H2-TPR and NH3-TPD. The results show that the cerium oxide is present on the surface of the catalyst; the peak of hydrogen consumption and the desorption of NH3 appear in the range of 100 ~ 600 ℃, indicating that it has some oxidation and acidity. The catalytic activity of the prepared catalyst for the degradation of trichlorethylene (TCE) was evaluated using a fixed bed continuous reactor apparatus at a space velocity of 15 000 h-1. The results show that the catalyst (1Cr-1Ce / H-MOR) has the best catalytic activity at n (Cr): n (Ce) = 1: 1 and the conversion of trichlorethylene reaches 90% at 279.4 ℃. Stability experiments showed that: after 400 min reaction, the conversion of TCE on the catalyst decreased by 9.2%. The results of XRD, TG and XPS indicated that there was no change in the catalyst structure and no apparent carbon deposition on the surface of the catalyst. The catalytic activity of 1Cr-1Ce / The decrease of n (Ce3 +) ratio and the adsorption of Cl species on the catalyst surface.