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挥发性有机物(VOCs,例如甲苯和二甲苯)不仅危害人身健康,而且对大气环境造成严重污染.由于去除效率高、无二次污染以及耗能低等优点,催化氧化法被认为是消除VOCs的有效方法之一.该方法的关键是高效催化剂的研发.由于具有良好的低温催化氧化性能,过渡金属氧化物负载的贵金属催化剂备受关注.相比于单组分贵金属负载型催化剂,双组分贵金属负载型催化剂的催化活性、水热稳定性能和抗硫中毒性能均有显著提高.本文采用熔融盐法和聚乙烯醇保护的硼氢化钠还原法制备了八面体状Co_3O_4负载的AuPd(x(AuPd_y)/Co_3O_4;AuPd负载量x=(0.18,0.47,0.97)wt%;Pd/Au摩尔比y=1.85,1.93,1.92)合金纳米催化剂.采用X射线衍射、扫描电子显微镜、透射电子显微镜、选区电子衍射、氢气程序升温还原、氧气程序升温脱附和X射线光电子衍射等技术对催化剂物化性质进行了表征.利用固定床微型反应器评价了催化剂对甲苯和邻二甲苯完全氧化反应的催化性能.研究结果表明,采用熔融盐法制得的Co_3O_4具有规整八面体形貌,棱长约为300 nm.AuPd合金纳米粒子均匀分布在Co_3O_4表面,粒径为2.7-3.2 nm.在所得催化剂中,0.96(AuPd_(1.92))/Co_3O_4催化剂对甲苯和邻二甲苯完全氧化反应表现出较高的催化活性.在空速为40000 mL/(g·h)时,甲苯和邻二甲苯转化率达到90%所需的温度分别为180和187℃.我们认为0.96(AuPd_(1.92))/Co_3O_4催化剂较为优异的催化性能与AuPd纳米粒子和Co_3O_4之间的强相互作用和较高的吸附氧浓度有关.
Volatile organic compounds (VOCs such as toluene and xylene) not only endanger human health but also cause serious pollution to the atmosphere. Due to their high removal efficiency, no secondary pollution and low energy consumption, catalytic oxidation is considered to eliminate VOCs One of the effective methods.This method is the key to the development of highly efficient catalysts.Because of its good low temperature catalytic oxidation performance, the transition metal oxide supported precious metal catalyst has drawn much attention.Compared with the single component noble metal supported catalyst, the two component The catalytic activity, hydrothermal stability and anti-sulfur poisoning performance of noble metal supported catalysts were significantly improved.In this paper, the octahedral Co_3O_4 supported AuPd (x ( AuPd_y) / Co_3O_4; the amount of AuPd loading x = (0.18,0.47,0.97) wt%; the molar ratio of Pd / Au y = 1.85,1.93,1.92) were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Selected area electron diffraction, temperature-programmed hydrogen reduction, oxygen temperature-programmed desorption and X-ray photoelectron diffraction were used to characterize the physical and chemical properties of the catalyst. The catalytic performance of the catalyst for the complete oxidation of toluene and o-xylene was evaluated.The results show that Co_3O_4 obtained by the molten salt method has a regular octahedron shape and the edge length is about 300 nm.AuPd alloy nanoparticles are uniformly distributed in the Co_3O_4 and the particle size of 2.7-3.2 nm.In the obtained catalyst, 0.96 (AuPd_ (1.92)) / Co_3O_4 catalyst showed high catalytic activity for the complete oxidation of toluene and o-xylene.When the space velocity was 40000 mL / (g · h), the temperatures required for the conversion of toluene and o-xylene to 90% are 180 and 187 ° C. We consider that the excellent catalytic performance of 0.96 (AuPd_ (1.92)) / Co_3O_4 catalyst is comparable to that of AuPd nanoparticles and Co_3O_4 strong interaction between the adsorption of oxygen concentration and higher.