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Pd-Cu-ClxAl2O3低温催化CO氧化的DFT研究

时间:2016-11-27 21:46来源:毕业论文
摘要:CO 低温氧化去除涉及到工业、军事、环保和人类生活的各个方面。在空气净化、封闭内循环式CO2 激光器、CO 气体传感器、CO 气体防毒面具、燃料池烟草降害以及密闭系统(如:飞

摘要:CO 低温氧化去除涉及到工业、军事、环保和人类生活的各个方面。在空气净化、封闭内循环式CO2 激光器、CO 气体传感器、CO 气体防毒面具、燃料池烟草降害以及密闭系统(如:飞机、潜艇、航天器等)内微量 CO消除等方面都具有很高的实用价值。同时,CO 氧化反应常被用作模型反应来研究催化材料的催化氧化性能和催化行为。对于催化CO低温氧化的非贵金属催化剂(单一金属氧化物和复合金属氧化物)主要存在以下问题:对水蒸气十分敏感,抗水性能差,表面吸附H2 O 后很快失活;低温催化活性较低,一般需要在100 o C 以上才能将CO完全氧化。 对于贵金属催化剂,主要存在问题有:Pd0、Pt0负载性催化剂活性比较差,一般需要在100 o C左右才能将CO完全转化;某些Pd0催化剂,如:Pd0/ CeO2 -TiO2 虽然在室温下能将CO完全氧化,但是其稳定性不高;虽然金催化剂具有良好的活性和抗水蒸气毒化性能,但是金催化剂对卤素很敏感,微量的卤素就能毒化Au催化剂的活性中心,因此在制备的过程中需要使用大量的去离子水洗涤,造成水资源的浪费。其次,金催化剂在贮藏或者是光照的条件下容易失活。而且,金催化剂的成本较高。Wacker-type催化剂虽然具有良好的稳定性和抗水性能,但与金催化剂或者Co3 O4 催化剂相比,其活性较低,在室温下无法将CO完全消除。高活性的催化剂稳定性较差,而稳定性较高的催化剂活性一般较低。因此,制备高活性、高稳定性的CO低温氧化催化剂具有一定的挑战性。针对CO低温氧化催化剂存在的缺点和不足,本文拟采用多种方法制备开发高活性、高稳定性并具有良好抗水蒸气毒化性能的Pd基催化剂,着重对以下内容开展了研究。 结合实验基础上,我们对CO在Walk催化剂表面的吸附展开计算研究,采用密度泛函的DFT理论,研究CO和O2在PdCl、PdCl2、CuCl和CuCl2表面的吸附。以期能够得到CO氧化关于反应活性位的确定,给实验提供参考。 源`自*六)维[论*文'网www.lwfree.cn
关键词:  CO, PdCl, PdCl2,CuCl,CuCl2,4017
DFT study of Pd-Cu-Clx/Al2O3 catalyst at low  temperature CO oxidation

Abstract: CO low-temperature oxidation removal relates to industrial, military, environmental protection and human life in all. In air purification, closed circulation type CO2 laser, CO gas sensor, CO gas masks, fuel tank tobacco harm reduction and closed system (such as: aircraft, spacecraft, submarines, etc.) microinjection of CO elimination and it has very high practical value. At the same time, catalytic oxidation properties and catalytic behavior of CO oxidation reaction is often used as a model reaction to study the catalytic materials.Non-noble metal catalysts for low-temperature CO oxidation (single metal oxides and composite metal oxides) mainly exists the following problems: very sensitive to water vapor, water resistance is poor, the adsorption of H2 O soon after inactivation; catalytic activity at low temperature is low, generally in more than 100 o C can be CO complete oxidation. For precious metal catalyst, the main problems are: Pd0, Pt0 loaded catalyst activity is relatively poor, the general needs in the 100 o C to CO transformation; some of the Pd0 catalyst, such as: Pd0/ CeO2 -TiO2 while at room temperature the oxidation of CO, but its stability is not high; the catalyst has good activity and resistance to water vapour poisoning performance, but the gold catalyst is very sensitive to the halogen, halogen can poison the catalyst active center of Au trace, so in the preparation process requires the use of deionized water washing large, resulting in the waste of water resources. Secondly, gold catalyst in storage or illumination conditions easy deactivation. Moreover, the high cost of gold catalysts. Wacker-type catalyst has good stability and water resistance, but compared with the gold catalyst or Co3 O4 catalyst, its low activity at room temperature, CO cannot be completely eliminated.The poor stability of catalyst with high activity and stability of catalyst, high activity is relatively low. Therefore, CO oxidation catalyst for preparation of high activity, high stability will be challenging. In view of the existing CO low-temperature oxidation catalyst and shortcomings, has good resistance to water vapor Pd catalyst poisoning performance, this paper uses a variety of methods for preparation of high activity, high stability and development, focuses on the following research.Combined with the experimental basis, we calculate the study of CO adsorption on the Walk catalyst, DFT theory using density functional theory, research on CO and O2 adsorption on PdCl, PdCl2, CuCl and CuCl2 surface. In order to get the CO oxidation on the determination of the reaction activity, providing reference for experiment. Pd-Cu-ClxAl2O3低温催化CO氧化的DFT研究:http://www.lwfree.cn/cailiao/20161127/468.html
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