【摘要】：揮發(fā)性有機(jī)物(VOCs,例如甲苯和二甲苯)不僅危害人身健康,而且對大氣環(huán)境造成嚴(yán)重污染.由于去除效率高、無二次污染以及耗能低等優(yōu)點(diǎn),催化氧化法被認(rèn)為是消除VOCs的有效方法之一.該方法的關(guān)鍵是高效催化劑的研發(fā).由于具有良好的低溫催化氧化性能,過渡金屬氧化物負(fù)載的貴金屬催化劑備受關(guān)注.相比于單組分貴金屬負(fù)載型催化劑,雙組分貴金屬負(fù)載型催化劑的催化活性、水熱穩(wěn)定性能和抗硫中毒性能均有顯著提高.本文采用熔融鹽法和聚乙烯醇保護(hù)的硼氫化鈉還原法制備了八面體狀Co_3O_4負(fù)載的AuPd(x(AuPd_y)/Co_3O_4;AuPd負(fù)載量x=(0.18,0.47,0.97)wt%;Pd/Au摩爾比y=1.85,1.93,1.92)合金納米催化劑.采用X射線衍射、掃描電子顯微鏡、透射電子顯微鏡、選區(qū)電子衍射、氫氣程序升溫還原、氧氣程序升溫脫附和X射線光電子衍射等技術(shù)對催化劑物化性質(zhì)進(jìn)行了表征.利用固定床微型反應(yīng)器評價(jià)了催化劑對甲苯和鄰二甲苯完全氧化反應(yīng)的催化性能.研究結(jié)果表明,采用熔融鹽法制得的Co_3O_4具有規(guī)整八面體形貌,棱長約為300 nm.AuPd合金納米粒子均勻分布在Co_3O_4表面,粒徑為2.7-3.2 nm.在所得催化劑中,0.96(AuPd_(1.92))/Co_3O_4催化劑對甲苯和鄰二甲苯完全氧化反應(yīng)表現(xiàn)出較高的催化活性.在空速為40000 mL/(g·h)時(shí),甲苯和鄰二甲苯轉(zhuǎn)化率達(dá)到90%所需的溫度分別為180和187℃.我們認(rèn)為0.96(AuPd_(1.92))/Co_3O_4催化劑較為優(yōu)異的催化性能與AuPd納米粒子和Co_3O_4之間的強(qiáng)相互作用和較高的吸附氧濃度有關(guān).
[Abstract]:Volatile organic compounds (VOCs, such as toluene and xylene) not only endanger human health, but also cause serious environmental pollution. Because of the advantages of high removal efficiency, no secondary pollution and low energy consumption, catalytic oxidation is considered to be one of the effective methods to eliminate VOCs. The key of this method is the research and development of high efficient catalyst. Due to their good catalytic performance at low temperature, transition metal oxide supported noble metal catalysts have attracted much attention. Compared with single-component noble metal supported catalysts, the catalytic activity, hydrothermal stability and sulfur poisoning resistance of two-component noble metal supported catalysts were significantly improved. In this paper, the octahedron Co_3O_4 loaded AuPd (x (AuPd_y / Co_3O_4;AuPd was prepared by melt salt method and polyvinyl alcohol protected sodium borohydride reduction method. The molar ratio of Pd/Au is 1.85%, 1.93% and 1.92%, respectively. The physicochemical properties of the catalyst were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, selective electron diffraction, hydrogen temperature programmed reduction, oxygen temperature programmed desorption and X-ray photoelectron diffraction. The catalytic performance of the catalyst for the complete oxidation of toluene and o-xylene was evaluated by a fixed bed microreactor. The results show that the Co_3O_4 prepared by molten salt method has regular octahedron morphology, the edge length is about 300 nm.AuPd alloy nanoparticles distributed uniformly on the surface of Co_3O_4, and the particle size is 2.7-3.2 nm.. Among the obtained catalysts, 0.96 (AuPd_ (1.92) / Co_3O_4 showed high catalytic activity for the complete oxidation of toluene and o-xylene. When the space velocity is 40000 mL/ (g h), the temperature required for the conversion of toluene and o-xylene to reach 90% is 180 鈩，

本文編號(hào)：2380332