【摘要】：作為備受關注的主要室內空氣污染物,甲醛(HCHO)會對人類身體健康與環(huán)境造成巨大破壞。在消除HCHO的眾多方法中,室溫完全催化氧化法被認為是最有效的方法,而催化劑的設計和制備是該法的關鍵。由于沸石分子篩負載Pt催化劑同時具有分子篩和貴金屬組分,它具備二者的組合優(yōu)勢,因此正逐漸成為室溫完全催化氧化HCHO的最有潛力的催化劑之一。目前已經有相關沸石分子篩負載Pt催化劑低溫完全催化氧化HCHO的探索工作,但在室溫下完全催化氧化HCHO依然是一個巨大的挑戰(zhàn)。本論文主要開展了一系列沸石分子篩負載Pt催化劑用于室溫完全催化氧化HCHO的活性研究,著重考察了分子篩載體的酸密度、骨架外陽離子種類和硅鋁比等因素對催化劑催化活性的影響。本文有四章,第一章為前言,第二章為實驗部分,研究結果主要在第三與第四章。在第三章中,我們將富鋁H-Beta分子篩負載Pt催化劑(Pt/H-Beta-SDS)與傳統(tǒng)H-Beta負載Pt催化劑(Pt/H-Beta-TEA)的活性作相比,結果前者表現(xiàn)出更為優(yōu)異的HCHO催化氧化性能。Pt/H-Beta-SDS催化劑在室溫條件下(25℃)實現(xiàn)對400 ppm HCHO的完全催化氧化,而在同樣條件下,Pt/H-Beta-TEA催化劑則需45 ℃。Pt/H-Beta-SDS如此高的HCHO室溫催化活性歸因于活性組分Pt具有更高的分散度和分子篩載體更加優(yōu)異的HCHO吸附能力。同時,我們也對比了Pt/H-Beta-SDS, Pt/Na-Beta-SDS和Pt/K-Beta-SDS催化劑的催化性能,結果發(fā)現(xiàn)Pt/H-Beta-SDS的催化活性遠遠高于后二者,我們通過反應拆分的手段證明了Na型和K型催化劑不利于HCHO氧化為甲酸的反應步驟,從而影響整個反應活性。在第四章中,我們通過制備了一系列不同硅鋁比(60,100,300,∞)與不同陽離子(H+,Na+,K+)的ZSM-5沸石分子篩,然后通過等體積浸漬法制備了上述分子篩負載1%Pt催化劑。反應結果表明,Pt/H-ZSM-5催化劑的催化活性遠遠高于Pt/Na-ZSM-5和Pt/K-ZSM-5催化劑,與第三章中結論一致。同時,分子篩硅鋁比同樣也影響著催化劑的催化活性,Pt/ZSM-5-Si催化劑具有最為優(yōu)異的室溫催化氧化甲醛的活性,我們把原因歸結于分子篩硅鋁比升高,導致催化劑疏水性也逐漸提高,這一方面增強了催化劑對HCHO的吸附能力。另一方面使得H20能更快地從催化中心脫附,從而促進反應的進行。最后,反應氣氛圍中引入水汽或者改變空速反應條件對上述催化劑的活性沒有顯著影響,而且更為重要的是催化劑的活性穩(wěn)定,壽命優(yōu)異。這表明這類催化劑具有較好的工業(yè)應用前景。
[Abstract]:As the main indoor air pollutant, formaldehyde (HCHO) will cause great damage to human health and environment. Among the many methods to eliminate HCHO, complete catalytic oxidation at room temperature is considered to be the most effective method, and the design and preparation of catalysts are the key to this method. Because the zeolites supported Pt catalyst has both molecular sieves and precious metal components, it has the advantages of the combination of the two, so it is gradually becoming one of the most potential catalysts for the complete catalytic oxidation of HCHO at room temperature. At present, there have been some researches on the complete catalytic oxidation of HCHO by zeolites supported Pt catalysts at low temperature, but the complete catalytic oxidation of HCHO at room temperature is still a great challenge. In this paper, a series of zeolites supported Pt catalysts for complete catalytic oxidation of HCHO at room temperature were studied, with emphasis on the effects of acid density, the type of cations outside the framework and the ratio of silicon to aluminum on the catalytic activity of the catalysts. This paper has four chapters, the first chapter is the preface, the second chapter is the experimental part, the research results are mainly in the third and fourth chapters. In chapter 3, we compare the activity of aluminum-rich H-Beta molecular sieves supported Pt catalyst (Pt/H-Beta-SDS) with that of traditional H-Beta supported Pt catalyst (Pt/H-Beta-TEA). The former shows better HCHO catalytic oxidation performance. PT / H-Beta-SDS catalyst realizes complete catalytic oxidation of 400 ppm HCHO at room temperature (25 鈩，

本文編號：2503298