化学镀法制备贵金属整体催化剂及其催化净化甲苯的研究
发布时间：2018-07-14 22:28
【摘要】：挥发性有机化合物(VOCs)是一类重要的大气污染物,对生态环境和人类健康有严重危害。催化燃烧可以在远低于直接燃烧温度条件下处理低浓度的VOCs气体,具有净化效率高、无二次污染、能耗低的特点,是商业上处理VOCs应用最有效的处理方法之一。催化燃烧技术的核心是开发高效燃烧催化剂,因此开发高活性、高稳定性的催化剂是目前催化燃烧法处理有机废气的关键任务。 鉴于化学镀法在制备铂钯等贵金属催化剂方面独特的优势,本文在化学镀钯的基础上,采用化学复合镀的方法原位掺入非贵金属锰的氧化物,制备钯基整体催化剂,以提高催化剂的催化性能和降低贵金属的用量；同时由于贵金属铂具有更优异的低温催化燃烧活性,因此还采用化学镀的方法制备了铂基和铂钯双金属掺杂型整体催化剂。主要的研究内容及结果如下： 采用新型的化学复合镀技术,在堇青石蜂窝陶瓷基体表面,使锰氧化物前躯体胶体颗粒与还原析出的钯金属颗粒同时交错沉积,再经高温热处理后即得到MnOX掺杂型钯基整体催化剂。从活性测试来看,与单钯催化剂相比,掺杂型钯基催化剂催化燃烧甲苯的活性有较大程度的提高,在钯质量负载量为0.36%时催化剂的活性最优,T99降低了约20℃。通过XRD、SEM、BET和紫外等表征结果可以发现,锰氧化物颗粒通过与钯组分颗粒的交错掺杂,有效促进了Pd组分的均匀分散,避免了Pd组分的迁移聚集长大,从而促进了催化催化性能的明显提高。同时通过对反应前后催化剂的XPS分析发现,掺杂型钯基催化剂在甲苯催化燃烧的反应中,由金属Pd和PdO协同作用共同促进催化反应的进行。 还采用化学镀技术,在堇青石蜂窝陶瓷基体表面直接负载贵金属铂制备了铂基整体催化剂。首先以甲苯催化燃烧为探针反应,得出化学镀铂的最佳制备条件为：化学镀时间为1-2小时,温度为30-50℃,还原剂需分批多次加入,焙烧温度为350℃。而且从催化剂反应性能和经济因素综合考虑,铂负载量为0.12wt%的Pt/蜂窝陶瓷整体催化剂的性价比最高,其在甲苯催化燃烧反应中T10和T99分别为163℃和180℃；同时该催化剂在较大空速范围(3000-40000h-1)和较宽进气甲苯浓度范围(0.5-8.0g/m3)内都能保持很高的催化燃烧活性；并在对催化剂进行的七次重复使用共93 h的稳定性测试中,甲苯转化率始终保持在99%以上。接着由催化剂的XRD、SEM和BET等表征分析发现,活性组分Pt在陶瓷基体表面以很小的颗粒均匀分布,但焙烧温度较高时易于聚集长大；同时由反应前后催化剂的XPS分析发现,铂基整体催化剂的催化活性受金属Pt和Pt的氧化物协同作用,而且参与反应的主要氧物种是表面吸附氧。最后还研究了钯掺杂对铂基整体催化剂的影响,发现在铂钯双金属催化剂中,铂组分对甲苯催化燃烧活性的贡献最大,但钯组分的加入能够有效提高催化剂的耐热稳定性。
[Abstract]:Volatile organic compounds (VOCs) are important atmospheric pollutants, which are harmful to the ecological environment and human health. Catalytic combustion is one of the most effective methods for commercial treatment of VOCs because of its high purification efficiency, no secondary pollution and low energy consumption. The core of catalytic combustion technology is to develop high efficiency combustion catalyst, so developing high activity and high stability catalyst is the key task of catalytic combustion method to treat organic waste gas. In view of the unique advantages of electroless plating in the preparation of noble metal catalysts such as platinum and palladium, based on the electroless plating of palladium, a palladium based monolithic catalyst was prepared by doping in situ the oxides of non-noble metal manganese by electroless composite plating. In order to improve the catalytic performance of the catalyst and reduce the amount of noble metal, and because the noble metal platinum has better catalytic combustion activity at low temperature, the platinum-based and platinum-palladium bimetallic doped monolithic catalyst was prepared by electroless plating. The main research contents and results are as follows: using a new type of electroless composite plating technology, the precursor colloidal particles of manganese oxide and the reduced precipitated palladium particles are interlaced on the cordierite honeycomb ceramic substrate. After high temperature heat treatment, MnOX doped palladium-based monolithic catalyst was obtained. Compared with the single palladium catalyst, the catalytic activity of the doped palladium based catalyst for toluene combustion was improved to a great extent, and the optimum activity of the catalyst was reduced by about 20 鈩，
本文编号：2123158
[Abstract]:Volatile organic compounds (VOCs) are important atmospheric pollutants, which are harmful to the ecological environment and human health. Catalytic combustion is one of the most effective methods for commercial treatment of VOCs because of its high purification efficiency, no secondary pollution and low energy consumption. The core of catalytic combustion technology is to develop high efficiency combustion catalyst, so developing high activity and high stability catalyst is the key task of catalytic combustion method to treat organic waste gas. In view of the unique advantages of electroless plating in the preparation of noble metal catalysts such as platinum and palladium, based on the electroless plating of palladium, a palladium based monolithic catalyst was prepared by doping in situ the oxides of non-noble metal manganese by electroless composite plating. In order to improve the catalytic performance of the catalyst and reduce the amount of noble metal, and because the noble metal platinum has better catalytic combustion activity at low temperature, the platinum-based and platinum-palladium bimetallic doped monolithic catalyst was prepared by electroless plating. The main research contents and results are as follows: using a new type of electroless composite plating technology, the precursor colloidal particles of manganese oxide and the reduced precipitated palladium particles are interlaced on the cordierite honeycomb ceramic substrate. After high temperature heat treatment, MnOX doped palladium-based monolithic catalyst was obtained. Compared with the single palladium catalyst, the catalytic activity of the doped palladium based catalyst for toluene combustion was improved to a great extent, and the optimum activity of the catalyst was reduced by about 20 鈩，
本文编号：2123158
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