【作者】 李振峰；

【导师】 季生福；

【作者基本信息】 北京化工大学 ， 化学工程， 2009， 硕士

【摘要】 随着社会经济的不断发展,挥发性有机物（VOCs）的污染问题越来严重。特别是其中的芳烃类严重污染了大气,对人们的身体健康构成了严重威胁,受到了广泛关注。在诸多的处理方法中,催化燃烧由于燃烧温度低、燃烧效率高、能耗低、无二次污染等优点被看做处理VOCs最具前景技术。在整个处理系统中,催化剂是比较关键的部分,其性能优劣直接关系到催化燃烧的效率。常用的催化剂有贵金属类,过渡金属氧化物类。贵金属催化剂活性较高,但考虑价格资源等因素,过渡金属氧化物除活性稍逊色外,其它方面其更具竞争力,对其进行了研究。首先以SiO₂为载体,MMn（M为Cu、Fe、Co、Ni）为活性组分,浸渍法制备了负载型催化剂。为提高催化性能,制备了Ce改性的FeMn系列催化剂,在常压下评价了其活性,及不同空速对催化剂活性的影响,进行了催化剂稳定性测试。评价结果表明:在FeMn/SiO₂体系中,Fe、Mn摩尔比相同时,活性组分含量为30%时催化剂有最佳活性;活性组分含量相同时,Fe、Mn摩尔比相同时催化活性最佳,在空速为3.4×10⁴ h^-1,甲苯浓度为1000ppm条件下,甲苯250℃起燃,280℃完全燃烧。空速升高,催化剂活性有一定下降。采用XRD,TPR对其进行了结构表征:活性组分含量低时,在载体表面均匀分布,但氧化还原性较弱;活性组分含量较高时,含量较多的物种在载体表面富集形成晶体,提高了催化剂氧化还原能力;以SBA-15为载体,CoMn为活性组分,浸渍法制备了负载型催化剂。评价了催化剂的性能、及不同空速条件下其活性,发现活性组分含量相同,CoMn摩尔比为3:7时,催化剂有较好活性;CoMn摩尔比为3:7,活性组分含量为35%时催化剂活性最佳:空速为3.4×10⁴ h^-1时,甲苯浓度1000ppm,甲苯235℃起燃,265℃完全燃烧。空速增大,催化剂活性先增大后降低。采用XRD,TPR,TEM,BET进行了结构表征:活性组分含量较高时,孔道有一定收缩,孔径、孔容、比表面积均有一定程度减少,但介孔结构仍然保持。为强化传热性能,减小压降,参考负载型催化剂活性数据的基础上,以CoMn氧化物为活性组分,FeCrAl合金片为第一载体,SBA-15、Al₂O₃为第二载体制备并评价了金属基催化剂的性能,考察了不同空速对催化剂性能的影响。活性组分含量相同时,CoMn摩尔比为3:7有最佳活性;固定CoMn摩尔比,活性组分含量为40%催化剂活性最佳,在空速为3.4×10⁴h^-1时,甲苯浓度为1000ppm,其250℃起燃,335℃完全燃烧。更多还原

【Abstract】 With the economic development of the society,the pollution of Volatile Organic Compounds（VOCs）,especially the aromatic gas becomes more and more serious.The aromatic gas compound is not only responsible for air pollution but is also harmful to people’s health.Recently,the removal of the aromatic gas has drawn much attention among researchers.In all of the methods used in VOCs processing,catalyst combustion is taken as the first method to be applied due to its advantages such as:low combustion temperature,few energy consumption and absence of secondary pollution.In this processing system,catalyst is the most important factor because the efficiency of the system depends on the catalyst activity.The common used catalysts are noble metals based-catalysts and transition metal-based catalysts.The noble metal-based catalysts have better activity. However,due to high cost and limited availability of noble metals,transition metal-based catalysts are preferred to noble metal-based catalysts although the former have a lower activity.For this reason we have conducted a research study on them.First of all,we have prepared the particle supported catalysts with SiO₂ as support and MMn as the active component（M stands for Cu,Fe,Co,Ni）.The FeMn-based catalysts modified with Ce promoter were also prepared in order to improve their activity and the evaluation of their activity was carried out at. atmospheric pressure.The effect of different Gas Hourly Space Velocities （GHSVs） on the catalyst activity as well as the stability of the catalyst were also investigated.The results of this investigation have shown that:in the catalyst system of FeMn/SiO₂,when Fe、Mn has the same molar ratio,the catalyst had better performance;when the content of active component is 30% and Fe,Mn had the same molar ratio,the catalyst performance was also the best:When the space velocity is 3.4×10⁴,toluene concentration of 1000ppm, toluene initial combustion at the temperature of 250℃,complete combustion at the temperature of 280℃.When the space velocity increased,the catalyst activity turned down to a certain degree.The characterization of the catalysts was carried out using some characterization methods such as XRD and TPR: when there is a few amount of the active component,this can uniformly be distributed on the support,but the reduction will be weak;when there is a lot of amount of active component,the excess amount of the active component would concentrate on the surface of support in the form of crystals,then the reduction of the catalyst would be increased indeed.Furthermore,the particle supported catalysts were prepared by the impregnation method with SBA-15 as support and CoMn oxide as the activity component.The catalyst activity,under different space velocities,was evaluated.It can be seen that when the activity component was maintained at the same value,with CoMn molar ratio of 3:7,the catalyst had better performance;and when the CoMn has the molar ratio of 3:7,the activity component of 35%,the catalyst performance is the best when the space velocity is 3.4×10⁴,toluene concentration of 1000ppm,toluene initial combustion at temperature of 235℃,complete combustion at temperature of 265℃.When the space velocity increases,the catalyst activity increases first and then decreases.The characterization of the catalysts was carried out using characterization methods such as XRD and TPR:BET,TEM:when the amount of the activity component is high,the channels of the support have a certain degree of contraction and the pore size,pore volume,specific surface area also decrease to some extent,but the stucture of the mesoporous is maintained.In order to enhance heat transfer performance,reduce the pressure drop encountered in previous particle catalysts,we prepared and evaluated the monolithic catalysts with a metallic support:With the same CoMn oxide as an active component,the FeCrAl metal was used as the first support,SBA-15, Al₂O₃ as the second support.The effect different space velocities on the catalyst activity was studied.The results have shown that when the active component of the catalysts were the same,with CoMn molar ratio of 3:7,the catalyst has better performance;when the CoMn molar ratio was kept at the same value,with the active component of 40%,the catalyst performance was the best.When the space velocity is 3.4×10⁴ h^-1,the concentration of toluene is 1000ppm,toluene initial combustion at the temperature of 250℃,toluene complete combustion at the temperature of 335℃.更多还原