本文關(guān)鍵詞：天然沸石負(fù)載Pt催化劑的HCHO室溫催化氧化研究　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 貴金屬催化劑 Pt 酸脫鋁 天然絲光沸石 甲醛催化氧化 堿金屬

【摘要】：作為重要的室內(nèi)空氣污染源之一,甲醛的脫除研究一直備受關(guān)注。在植物凈化、化學(xué)吸附、催化氧化等甲醛脫除方法中,催化氧化法由于其具有能耗低、壽命長(zhǎng)、無(wú)二次污染等特點(diǎn)而更受研究者的關(guān)注。根據(jù)近十年來(lái)甲醛催化氧化的相關(guān)研究,貴金屬催化劑在甲醛的低溫催化氧化方面具有特別的優(yōu)勢(shì)。通過(guò)對(duì)比,貴金屬Pt又在眾多貴金屬中脫穎而出,成為甲醛室溫催化氧化的研究重點(diǎn)。本文以天然絲光沸石為載體,成功合成了可以在室溫下實(shí)現(xiàn)HCHO完全催化氧化的Pt/MORn系列催化劑。首先從載體入手,研究天然絲光沸石的預(yù)處理對(duì)催化活性的影響。使用到的預(yù)處理方式為酸處理、堿處理和離子交換處理。綜合對(duì)比研究發(fā)現(xiàn),酸處理后的催化劑催化活性最好,堿處理次之,離子交換處理效果最不明顯。不同濃度和步驟的酸處理對(duì)沸石的除雜和脫鋁程度呈規(guī)律性變化,但是當(dāng)酸處理達(dá)到一定程度后,其對(duì)催化活性的促進(jìn)作用會(huì)明顯降低,綜合對(duì)比后認(rèn)為6M硝酸處理為最佳酸處理方式;堿處理由于引入了堿金屬離子和羥基,對(duì)活性也有較大提高,但是由于其除雜效果較差、不能實(shí)現(xiàn)脫鋁和提高比表面積,因此其催化活性比酸處理后的催化劑低;天然絲光沸石經(jīng)離子交換處理后負(fù)載Pt合成的催化劑對(duì)甲醛的室溫催化氧化幾乎沒(méi)有效果,將酸處理后的沸石進(jìn)行離子交換也不能進(jìn)一步提高其催化活性。除了載體效應(yīng)的研究,本論文中還探討了貴金屬Pt的負(fù)載量、合成過(guò)程中的煅燒溫度以及不同Na+添加量、不同Na源對(duì)催化劑活性的影響。研究表明,以經(jīng)過(guò)6M硝酸處理后的天然絲光沸石作為載體的條件下,Pt負(fù)載量在0.1-2.0wt.%區(qū)間內(nèi)的最佳負(fù)載量為0.5 wt.%;煅燒溫度在200-500 ℃范圍內(nèi)對(duì)催化活性的影響較小;分別采用NaOH和Na2C03作為鈉添加劑對(duì)Pt/MORn催化劑的作用呈現(xiàn)出相似的趨勢(shì),NaOH額外引入羥基對(duì)催化劑活性并無(wú)明顯提升;Na添加量對(duì)催化劑活性的影響與文獻(xiàn)中不完全一致,本研究中Na添加量為0.5 wt.%時(shí),對(duì)催化劑活性表現(xiàn)出抑制作用;當(dāng)Na添加量進(jìn)一步增加,催化劑活性會(huì)不斷提高,在添加量為2.0wt.%時(shí)的室溫甲醛轉(zhuǎn)化率超過(guò)95%。
[Abstract]:As one of the most important indoor air pollution sources, formaldehyde removal has attracted much attention. In plant purification, chemical adsorption, catalytic oxidation and other formaldehyde removal methods, catalytic oxidation has low energy consumption. Long life, no secondary pollution and other characteristics have attracted more attention of researchers. According to the research of catalytic oxidation of formaldehyde in recent ten years. Precious metal catalysts have a special advantage in the low-temperature catalytic oxidation of formaldehyde. Through comparison, the noble metal Pt stands out among many precious metals. In this paper, natural mordenite was used as the carrier. A series of Pt/MORn catalysts which can realize the complete catalytic oxidation of HCHO at room temperature have been successfully synthesized. The effects of pretreatment of natural mordenite on catalytic activity were studied. The pretreatment methods were acid treatment, alkali treatment and ion exchange treatment. The comprehensive comparative study showed that the catalyst with acid treatment had the best catalytic activity. After alkali treatment, the effect of ion exchange treatment was the least obvious. The degree of impurity removal and de-aluminization of zeolite changed regularly with different concentration and step of acid treatment, but when the acid treatment reached a certain degree. The promoting effect of 6M nitric acid treatment on the catalytic activity will be obviously reduced, and it is considered that 6M nitric acid treatment is the best way of acid treatment. The alkali treatment can improve the activity greatly because of the introduction of alkali metal ions and hydroxyl groups, but because of its poor impurity removal effect, it can not achieve dealumination and improve the specific surface area. Therefore, its catalytic activity is lower than that after acid treatment. The catalyst supported on Pt synthesis after ion exchange treatment has little effect on the catalytic oxidation of formaldehyde at room temperature. In addition to the study of carrier effect, the loading amount of noble metal Pt was also discussed in this paper. The effects of calcination temperature, Na addition amount and Na source on the activity of the catalyst were studied. The results showed that the natural mordenite treated with 6M nitric acid was used as the carrier. The optimum loading amount of Pt in the range of 0.1-2.0wt.% is 0.5 wt.; The calcination temperature has little effect on the catalytic activity in the range of 200-500 鈩，

本文編號(hào)：1370892