【作者】 赵福真；

【导师】 季生福；

【作者基本信息】 北京化工大学 ， 化学工程， 2010， 博士

【摘要】 石油化工企业的一些催化反应过程的尾气排放和机动车的尾气排放已引起了一系列的环境问题,对人类的健康造成了极大的危害,其中,CO和可挥发性有机废气(VOCs)是污染物之一。发达国家都制定了严格的排放标准来控制CO和VOCs的排放。催化燃烧技术对于改善燃烧过程,降低反应温度,抑制有毒有害物质的形成等方面有着明显的优势,成为废气处理的重要手段。介孔材料SBA-15具有较大的比表面积、规则的孔道结构,有望成为催化燃烧高效催化剂的新型载体。与传统的颗粒状催化剂相比,整体式催化剂具有床层压降低、反应物径向分布均匀和传递特性好等特点,对于具有较大空速和强吸热、放热的反应具有很好的应用前景。本文以低浓度CO和甲苯催化消除为研究对象,制备了多个系列的新型催化剂,研究了催化剂的结构和性能。对于CO催化氧化反应,以Cu、Ce为活性组分,SiO2和SBA-15为载体制备了CuxCe1-xO2-x/SiO2和CuxCe1-xO2-x/SBA-15负载型催化剂；同时以CuxCe1-xO2-x/SBA-15为活性浆料,FeCrAl金属薄片和堇青石蜂窝陶瓷为基体,制备了CuxCe1-xO2-x/SBA-15/FeCrAl和CuxCe1-xO2-x/SBA-15/堇青石新型整体式催化剂,评价了催化剂的性能,测定了催化剂的反应活化能。对于甲苯催化燃烧消除,制备了CuxCo1-x/SBA-15负载型催化剂和CuxCo1-x/Al2O3/FeCrAl、CuxCo1-x/Al2O3/堇青石新型整体式催化剂,评价了催化剂的性能。并且利用XRD、N2-吸脱附、HRTEM、XPS、SEM和H2-TPR等表征手段,对所有催化剂的结构进行了表征,深入研究了催化剂的结构和性能的关系。主要研究结果如下：在CuxCe1-xO2-x/SiO2系列催化剂中,25%Cu0.5Ce0.501.5/SiO2催化剂具有最好的CO催化氧化活性,当空速为34,000h-1时,在169℃时CO可以完全氧化；对于Cu、Ce摩尔比为1：1的催化剂,当Cu0.5Ce0.5O1.5含量较低时,催化剂的物相主要是CuO-CeO2固溶体,含量比较大时还出现了CuO物相；对于不同Cu、Ce摩尔比的催化剂,Cu摩尔含量较高时主要是CuO物相,Cu摩尔含量较低时主要是CuO-CeO2固溶体和CeO2物相。在CuxCe1-xO2-x/SBA-15系列催化剂中,30%Cu0.5Ce0.5O1.5/SBA-15催化剂活性最好,在48,000h-1空速下,在156℃时CO可以实现完全氧化,其活化能为70.6 kJ/mol;对于Cu、Ce摩尔比为1：1的催化剂,当Cuo.5Ce0.5O1.5含量≤10%时,催化剂的物相主要是CuO-CeO2固溶体,含量高时还出现了CuO物相；对于不同Cu、Ce摩尔比的催化剂,Cu摩尔含量比较高时,主要是CuO物相,Cu摩尔含量较低时主要是CuO-CeO2固溶体和CeO2物相。在CuxCe1-xO2-x/SBA-15/FeCrAl整体式催化剂中，50%Cu0.5Ce0.501.5/SBA-15/FeCrAl催化剂表现出最好的活性,在空速为36,000ml/(g·h)时,在142℃时CO可以完全消除；当Cu、Ce摩尔比例为1：1,Cu0.5Ce0.5O1.5含量≥40%时,整体式催化剂上可以测到CuO物相；50%Cu0.7Ce0.3O1.3/SBA-15/FeCrAl催化剂具有很好的稳定性,在经过1306h的稳定性测试后,仍然表现出很好的CO催化氧化活性。在CuxCe1-xO2-x/SBA-15/堇青石整体式催化剂中，50%Cu0.5Ce0.5O1.5/SBA-15/堇青石催化剂具有最好的催化活性,当气体空速为33,000ml/(g·h)时,CO可以在120℃完全转化；当Cu、Ce摩尔比例为1:1,Cu0.5Ce0.5O1.5含量≥40%时,整体式催化剂上可以测到CuO物相。在CuxCo1-x/SBA-15系列催化剂中,40%Cu0.25Co0.75/SBA-15催化剂活性最好,甲苯在285℃可完全转化；结构研究表明,催化剂仍然具有SBA-15的介孔结构,但其比表面积、孔容和孔径相对于SBA-15都有所下降；催化剂中Cu含量较低时存在Cu-Co-O固溶体,Cu含量较高时会形成CuO物相。在CuxCo1-x/Al2O3/FeCrAl整体式催化剂中,Cu0.5Co0.5/A12O3/FeCrAl具有最好的活性,在56,380ml/g·h空速下,可以在357℃完全燃烧消除甲苯。XPS结果表明,整体式催化剂表面同时存在着Co2+和Co3+,而Cu主要以Cu2+物种存在；Cu的含量可以改变Co的氧化还原性,对催化剂的活性有一定的影响。在CuxCo1-x/Al2O3/堇青石整体式催化剂中,活性最好的Cu0.5Co0.5/Al2O3/堇青石催化剂在56,380ml/g·h空速下,可以在315℃使甲苯完全燃烧。当x=0-0.5时,催化剂上只能测到堇青石的特征峰；在x>0.5时,催化剂上出现了CuO的特征峰。更多还原

【Abstract】 Lots of exhausts coming from the petrol-chemical plants and automobiles have induced many troublesome environmental problems. CO and VOCs are the main exhausts. The developed countries have made many strict effluent standards to control the discharge of CO and VOCs. Catalytic combustion has been recognized as one of the most important technologies to destroy CO and VOCs at low temperature. This method has many advantages such as low temperature required for combustion ignition, high energy efficiency, and avoiding the formation of toxic byproducts. The mesoporous silica material SBA-15 may be a promising new type of porous support for catalytic combustion, due to its high surface area, highly ordered pore structure and uniform pore size distribution. Comparing to the conventional catalyst, the monolithic catalyst has distinct advantages, such as low-pressure drop, favorable heat and mass transfer properties and minimum axial dispersion. Thus for the reactions with high space velocity and heat exchange, the monolithic catalysts have a promising application.In this paper, A series of new type catalysts were prepared for the oxidation of low concentration CO and toluene. The structure and the catalytic activity of the catalysts were investigated. The CuxCe1-xO2-x/SiO2, CuxCe1-x/SBA-15 supported catalysts and CuxCe1-xO2-x/SBA-15/FeCrAl, CuxCe1-xO2-x/SBA-15/cordierite monolithic catalysts were prepared. Their catalytic performances for the catalytic combustion of CO were tested and the activation energies were calculated. CuxCo1-x/SBA-15 supported catalysts and CuxCo1-x/Al2O3/FeCrAl、CuxCo1-x/Al2O3/cordierite monolithic catalysts were prepared and their catalytic performances for the catalytic combustion of toluene were tested. The structure of the catalysts was characterized by XRD, N2 adsorption-desorption, HRTEM, XPS, SEM and H2-TPR. The relationship between the catalytic performance and the structure of the catalysts was studied. The main results are listed as follows:For the CuxCe1-xO2-x/SiO2 series catalysts,25%Cu0.5Ceo.5O1.5/SiO2 catalyst showed the best activity and CO could be totally oxidized at 169℃when GHSV=34,000h-1. For the catalysts with the same Cu/Ce molar ratios, the main phase was CuO-CeO2 solid solution when the content of Cuo.5Ceo.501.5 was low, while the CuO phase could be found at higher Cuo.5Ceo.5O1.5 content. For the catalysts with different Cu/Ce molar ratios, CuO was the main phase when the content of Cu is high, while the main phases were CuO-CeO2 solid solution and CeO2 when the content of Cu is low.For the CuxCe1-xO2-x/SBA-15 catalysts,30%Cuo.5Ceo.5O1.5/SBA-15 catalyst with the lowest activation energy 70.6 kJ/mol showed the best activity and CO could be totally oxidized at 156℃when GHSV=48,000h-1. For the catalysts with the same Cu/Ce molar ratios, the main phase was CuO-CeO2 solid solution when the content of Cu0.5Ce0.5O1.5 was less than 10%, while the CuO phase could be found at higher Cu0.5Ce0.5O1.5 content. For the catalysts with different Cu/Ce molar ratios, CuO was the main phase when the content of Cu is high, while the main phases were CuO-CeO2 solid solution and CeO2 when the content of Cu is low.For the CuxCe1-xO2-x/SBA-15/FeCrAl monolithic catalysts, 50%Cu0.5Ce0.5O1.5/SBA-15/FeCrAl catalyst showed the best activity and CO could be totally oxidized at 142℃when GHSV=36,000ml/g·h. For the catalysts with the same Cu/Ce molar ratios, the CuO phase only could be found when the content of Cu0.5Ce0.5O1.5 was more than 40%. The 50%Cu0.7Ce0.301.3/SBA-15/FeCrAl catalyst showed an excellent stabile performance, the activity remained the same 97% CO conversion during the 1306 h of stability reaction,For the CuxCe1-xO2-x/SBA-15/cordierite series catalysts, 50%Cu0.5Ce0.501.5/SBA-15/cordierite catalyst showed the best activity and CO could be totally oxidized at 120℃when GHSV=33,00Oml/g·h. For the catalysts with the same Cu/Ce molar ratios, the CuO phase only could be found when the content of Cu0.5Ce0.5O1.5 was more than 40%.For the CuxCo1-x/SBA-15 supported catalysts,40%Cu0.25Co0.75/SBA-15 catalyst showed the highest catalytic activity. Toluene can be completely oxidized at 285℃with a GHSV of 34,000 ml/g·h. The loading of Cu, Co affects the surface area, pore volume and average pore diameter of SBA-15, but the mesoporous structure was maintained. The results indicated that Cu-Co-O compound was observed when the Cu content was low. The peaks of CuO were observed when the Cu content was high.For the CuxCo1-x/Al2O3/FeCrAl series catalysts, Cuo.5Coo.5/Al203/FeCrAl catalyst showed the best activity and toluene could be totally oxidized at 357℃when GHSV=56,380ml/g-h. The XPS results showed that both Co2+ and Co3+existed in the obtained monolithic catalysts, and Cu existed mainly as Cu2+species. When x<0.5, the introduction of copper oxide improved the reducibility of the cobalt oxide and enhanced the catalytic activity of the catalysts.For the CuxCo1-x/Al2O3/cordierite series catalysts, Cu0.5Co0.5/Al203/cordierite catalyst showed the best activity and toluene could be totally oxidized at 315℃when GHSV=56,380ml/g·h. When x was more than 0.5, the CuO phase could be found.更多还原