【作者】 吴波；

【导师】 程琰；

【作者基本信息】 西南交通大学 ， 环境工程（专业学位）， 2017， 硕士

【摘要】 挥发性有机气体是大气污染的重要来源,可引发如光化学污染、臭氧层破坏、雾霾等严重的大气污染问题,给人类生存环境带来极大影响。控制VOC的催化燃烧技术由于其能耗低,无二次污染等优点得到广泛运用。VOCs催化燃烧技术的关键是催化剂,但目前工业生产过程中所使用的贵金属催化剂存在价格昂贵、资源稀缺、稳定性差等问。因此,研究开发价格低廉,活性优良的VOCs催化剂很有必要。过渡金属氧化物中铜、锰、铈的金属氧化物稳定性好、价格低廉,但其催化性能仍有待进一步提高。本文确定了包含铜、锰、铈三种金属元素的三个系列的复合氧化物催化剂的最佳制备条件,测试了其VOCs催化活性,确定了其中催化性能最优的催化燃烧催化剂,并采用N2吸脱附、XRD、SEM、H2-TPR等表征手段分析催化剂的结构性能变化。本文考察了催化剂制备方法、活性组分比例、煅烧温度和空速等工艺条件对催化剂VOCs催化活性的影响,确定了锰铈复合氧化物催化剂最优制备方案为;采用共沉淀法制备,活性组分Mn:Ce为0.3:0.7,锻烧温度为650℃。研究结果表明:(1)Mn-Ce复合氧化物催化剂中形成的Mn-Ce固溶体,可能有利于催化剂催化活性的提升。(2)共沉淀法制备的催化剂拥有较高的比表面积、表面活性组分分散更均匀、具有良好的孔道结构以及较好的氧化还原能力。(3)催化剂煅烧温度适度增加有利于催化剂的活性的提升,而煅烧温度过高可能导致催化剂活性组分发生聚集,甚至坍塌现象,从而影响催化剂的催化性能。根据上述催化剂最佳制备条件,制备了铜铈系列和铜锰系列催化剂。在甲苯进口浓度为500ppm,空速为30000h-1的操作条件下,分别考察了这两个系列催化剂的催化性能。活性测试结果表明,在铜铈系列催化剂中,Cu:Ce=0.3:0.7的催化剂对甲苯催化活性最好(T90=229℃)。在铜锰系列催化剂中,Cu:Mn=0.25:0.75的催化剂表现出最优的催化性能(T90=202℃)。研究结果表明,(1)铜铈系列催化剂中,Cu-Ce复合氧化物催化剂均为介孔结构,CuO和CeO2之间存在良好的协同作用;适当比例的铜铈混合可得到活性组分分散较均匀,比表面积和孔容较高的催化剂。(2)铜锰系列催化剂中,Cu-Mn复合氧化物催化剂均为介孔结构。催化剂中铜锰元素存在较强相互作用,并检测出了尖晶石结构,这可能有利于催化剂氧化还原性能和催化活性的提高。本文比较了在相同条件下铜锰、铜铈、锰铈三个系列的催化剂中结构性能最优的催化剂,比较了对甲苯和乙酸乙酯的催化活性。其中,Cu:Mn=0.25:0.75的铜锰复合氧化物催化剂性能最优,在空速为30000h-1操作条件下,处理进口浓度为500ppm的甲苯的完全转化温度为T90为202℃,处理进口浓度为1000ppm的乙酸乙酯的完全转化温度为 T90 为 212℃。更多还原

【Abstract】 VOCs is an important source of atmospheric pollution,which can cause serious air pollution problems,such as photochemical pollution,ozone damage,haze.These problems have a great impact on the human living environment.Catalytic combustion technology because of its low energy consumption,no secondary pollution and other advantages are widely used.For the VOC emission control,the key to VOCs catalytic combustion technology is good catalyst.but the noble metal catalysts widely used in current industrial processes is expensive and have poor stability.Therefore,it is necessary to research low price and excellent activity of VOCs catalyst.Copper oxide,manganese oxide and ceria are stable and cheap,but their catalytic performance still needs to be further improved.In this paper,three series of composite oxide catalysts containing copper,manganese and cerium were prepared,and the catalytic activity to VOCs was tested.N2 desorption,XRD,SEM and H2-TPR were used to analyze the catalytic mechanism of the catalyst,and the catalytic with the best catalytic performance was determined.In this paper,the effects of catalyst preparation methods,ratio of active components,calcination temperature and space velocity on the catalytic activity to VOCs.were investigated.The optimal preparation scheme of Mn-Ce composite oxide catalyst was determined as follows:Mn:Ce = 0.3:0.7;the catalyst preparation method adopts coprecipitation method;the calcination temperature of the catalyst is 650℃.In this paper,it is verified that the working conditions of space velocity have a great influence on the catalytic activity of Mn-Ce composite oxide catalyst,which will increase the complete conversion temperature of VOCs in the experiment.The results show that:（1）Mn-Ce solid solution formed in Mn-Ce composite oxide catalyst may be beneficial to the catalytic activity of the catalyst.（2）The catalyst prepared by coprecipitation method has a high specific surface area,and the surface active components are dispersed more uniformly,have good pore structure and better redox ability.（3）The increase of the calcination temperature of the catalyst is beneficial to the activity of the catalyst,and the high calcinations temperature may lead to the aggregation and even collapse of the catalyst active components,thus affecting the catalytic performance of the catalyst.In this paper,copper-cerium series and copper-manganese series catalysts were prepared under the optimum preparation conditions.Under the condition of toluene inlet concentration of 500ppm and space velocity of 30000h-1,the catalytic performance of these two series of catalysts was investigated.The results show that Cu:Ce = 0.3:0.7 has the best catalytic activity for toluene（T90 = 229 ℃）in copper cerium series catalysts.In the copper一manganese series catalyst,Cu:Mn = 0.25:0.75 catalyst showed the best catalytic activity of toluene（T90 = 202 ℃）.The results of the activity test showed that,（1）Cu-Ce composite oxide catalysts are slit mesoporous structures in Cu-Ce series catalysts,and there is a good synergistic effect between CuO and CeO2,which is favorable for oxidation-reduction performance and catalytic performance.A suitable proportion of the copper-cerium mixture can be obtained by dispersing the active ingredient uniformly,the size and shape of the more regular catalyst to enhance the catalyst’s specific surface area and pore volume.（2）In the Cu-Mn series catalysts,the Cu-Mn composite oxide catalysts have mesoporous structure,and the copper-manganese elements in the catalysts have strong interaction,and the spinel structure is detected in the catalyst,to improve the redox performance of the catalyst,which improves the redox performance and catalytic performance of the catalyst.In this paper,the catalytic activity for toluene and ethyl acetate of the catalyst with best structure and performance in copper manganese,copper cerium and manganese cerium three series of catalysts,The catalyst with Cu:Mn = 0.25:0.75 was the best catalyst for the catalytic activity,The complete conversion temperature of toluene at a feed concentration of 500 ppm was 202℃ at a space velocity of 30000 h-1 and the complete conversion temperature of ethyl acetate at a feed concentration of 1000 ppm was 212℃ at a space velocity of 30000 h^-1.更多还原