【摘要】：揮發(fā)性有機(jī)化合物(VOCs)是一類重要的大氣污染物,對(duì)生態(tài)環(huán)境和人類健康有嚴(yán)重危害。催化燃燒可以在遠(yuǎn)低于直接燃燒溫度條件下處理低濃度的VOCs氣體,具有凈化效率高、無二次污染、能耗低的特點(diǎn),是商業(yè)上處理VOCs應(yīng)用最有效的處理方法之一。催化燃燒技術(shù)的核心是開發(fā)高效燃燒催化劑,因此開發(fā)高活性、高穩(wěn)定性的催化劑是目前催化燃燒法處理有機(jī)廢氣的關(guān)鍵任務(wù)。 鑒于化學(xué)鍍法在制備鉑鈀等貴金屬催化劑方面獨(dú)特的優(yōu)勢,本文在化學(xué)鍍鈀的基礎(chǔ)上,采用化學(xué)復(fù)合鍍的方法原位摻入非貴金屬錳的氧化物,制備鈀基整體催化劑,以提高催化劑的催化性能和降低貴金屬的用量；同時(shí)由于貴金屬鉑具有更優(yōu)異的低溫催化燃燒活性,因此還采用化學(xué)鍍的方法制備了鉑基和鉑鈀雙金屬摻雜型整體催化劑。主要的研究內(nèi)容及結(jié)果如下： 采用新型的化學(xué)復(fù)合鍍技術(shù),在堇青石蜂窩陶瓷基體表面,使錳氧化物前軀體膠體顆粒與還原析出的鈀金屬顆粒同時(shí)交錯(cuò)沉積,再經(jīng)高溫?zé)崽幚砗蠹吹玫組nOX摻雜型鈀基整體催化劑。從活性測試來看,與單鈀催化劑相比,摻雜型鈀基催化劑催化燃燒甲苯的活性有較大程度的提高,在鈀質(zhì)量負(fù)載量為0.36%時(shí)催化劑的活性最優(yōu),T99降低了約20℃。通過XRD、SEM、BET和紫外等表征結(jié)果可以發(fā)現(xiàn),錳氧化物顆粒通過與鈀組分顆粒的交錯(cuò)摻雜,有效促進(jìn)了Pd組分的均勻分散,避免了Pd組分的遷移聚集長大,從而促進(jìn)了催化催化性能的明顯提高。同時(shí)通過對(duì)反應(yīng)前后催化劑的XPS分析發(fā)現(xiàn),摻雜型鈀基催化劑在甲苯催化燃燒的反應(yīng)中,由金屬Pd和PdO協(xié)同作用共同促進(jìn)催化反應(yīng)的進(jìn)行。 還采用化學(xué)鍍技術(shù),在堇青石蜂窩陶瓷基體表面直接負(fù)載貴金屬鉑制備了鉑基整體催化劑。首先以甲苯催化燃燒為探針反應(yīng),得出化學(xué)鍍鉑的最佳制備條件為：化學(xué)鍍時(shí)間為1-2小時(shí),溫度為30-50℃,還原劑需分批多次加入,焙燒溫度為350℃。而且從催化劑反應(yīng)性能和經(jīng)濟(jì)因素綜合考慮,鉑負(fù)載量為0.12wt%的Pt/蜂窩陶瓷整體催化劑的性價(jià)比最高,其在甲苯催化燃燒反應(yīng)中T10和T99分別為163℃和180℃；同時(shí)該催化劑在較大空速范圍(3000-40000h-1)和較寬進(jìn)氣甲苯濃度范圍(0.5-8.0g/m3)內(nèi)都能保持很高的催化燃燒活性；并在對(duì)催化劑進(jìn)行的七次重復(fù)使用共93 h的穩(wěn)定性測試中,甲苯轉(zhuǎn)化率始終保持在99%以上。接著由催化劑的XRD、SEM和BET等表征分析發(fā)現(xiàn),活性組分Pt在陶瓷基體表面以很小的顆粒均勻分布,但焙燒溫度較高時(shí)易于聚集長大；同時(shí)由反應(yīng)前后催化劑的XPS分析發(fā)現(xiàn),鉑基整體催化劑的催化活性受金屬Pt和Pt的氧化物協(xié)同作用,而且參與反應(yīng)的主要氧物種是表面吸附氧。最后還研究了鈀摻雜對(duì)鉑基整體催化劑的影響,發(fā)現(xiàn)在鉑鈀雙金屬催化劑中,鉑組分對(duì)甲苯催化燃燒活性的貢獻(xiàn)最大,但鈀組分的加入能夠有效提高催化劑的耐熱穩(wěn)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，

本文編號(hào)：2123158