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针对有毒有害的含氯挥发性有机化合物废气的催化氧化脱除,从稀土氧化物(Ce和La)出发,以饱和含氯代烃(二氯甲烷,二氯乙烷等)和不饱和氯代烃(氯苯,氯乙烯)为模型反应;详细分析了稀土修饰(Ce,La)或以稀土为主的催化剂(CeO_2,La MnO_3)对氯代烃催化燃烧的影响。以催化剂表面的酸性中心和氧化还原性能为主线,分析了二者在氯代烃催化燃烧反应过程中的作用,酸中心与催化剂CO选择性、积碳相关;而多氯副产物的生成和分布则受催化剂氧化性能的影响。在此基础上提出氯代烃的催化燃烧催化剂的设计思路,结合氯代烃分子结构差异,调控催化剂表面酸性中心和氧化还原性能之间的匹配,提高催化剂的低温反应活性、兼顾含碳(氯)副产物的选择性、避免催化剂积碳、氯中毒的现象,增加催化剂的稳定性。
Aiming at the catalytic oxidation removal of toxic and harmful chlorine-containing volatile organic compounds (VOCs), starting from rare earth oxides (Ce and La), saturated chlorinated hydrocarbons (dichloromethane, dichloroethane and the like) and unsaturated chlorides (Chlorobenzene and vinyl chloride) were used as model reactions. The effects of rare earth-modified (Ce, La) or rare earth-based catalysts (CeO_2 and LaMnO_3) on the catalytic combustion of chlorinated hydrocarbons were analyzed in detail. The acid centers and redox properties of the catalyst surface were used as the main lines to analyze the role of the two in the catalytic combustion of chlorinated hydrocarbons. The acid sites were related to the CO selectivity and carbon deposition of the catalyst. The formation and distribution of polychlorinated by-products Is affected by the catalyst oxidation performance. On the basis of this, the design of catalyst for catalytic combustion of chlorinated hydrocarbons is proposed. Combining with the molecular structure of chlorinated hydrocarbons, the match between the acid sites on the surface of catalysts and the redox properties of catalysts is controlled, and the low temperature reactivity of catalysts is improved. ) By-product selectivity, to avoid carbon deposition of the catalyst, chlorine poisoning phenomenon, increase the stability of the catalyst.