Abstract:
The removal of chlorinated volatile organic compounds (CVOCs) by catalytic combustion is one of the research hotspots in recent years. Zeolite materials have attracted extensive attention arising from their rich pore structures, large specific surface area and abundant acid sites. In this paper, Ce-USY catalysts with different Ce doping contents were synthesized by liquid phase ion exchange method. The activity and stability for degradation of DCE, a common and highly toxic kind of CVOCs, on different samples in different reaction atmospheres (aqueous or benzene) were determined. Besides, XRD, H2-TPR, NH3-TPD and other techniques were performed for sample characterization and analysis. The results showed that the catalytic degradation performance increased with the augment amount of Ce doping.The Ce saturation exchange mass fraction was about 4.0%, and the T90% (the temperature at which DCE conversion rate reaches 90%) of corresponding catalyst was 90 ℃ lower than that of HUSY. Through the characterization analysis, it was found that CeO2 effectively increased the acidity sites and the oxygen species on the catalyst surface, and produced an obvious catalytic synergy with zeolite, which significantly improved the activity, selectivity and stability of the catalyst. The stability test results also indicated that the presence of water could remove Cl species adsorbed on the surface of HUSY zeolite and inhibit carbon deposition, which benefited the stability of the catalyst. With the presence of benzene, Ce-USY catalyst was more prone to carbon deposition and deactivation due to the presence of more strong Lewis acid and Brφnsted acid sites on the surface of the catalyst.
