【摘要】：氯乙烯(VCM)是生產(chǎn)重要化工產(chǎn)品聚氯乙烯(PVC)的單體。全球每年生產(chǎn)PVC逾4000萬(wàn)噸,中國(guó)占其中的60%以上�；谖覈�(guó)富煤、貧油、少氣的能源現(xiàn)狀,我國(guó)75%以上的PVC采用以煤炭為原料的乙炔氫氯化法生產(chǎn)。目前全球有超過(guò)70個(gè)國(guó)家和地區(qū)簽署了《水俁公約》,規(guī)定從2020年起,凡簽署了《公約》的國(guó)家均禁止生產(chǎn)及進(jìn)出口含汞產(chǎn)品,所以研究開(kāi)發(fā)新型高效的無(wú)汞催化劑是PVC生產(chǎn)行業(yè)亟待解決的問(wèn)題。本文探討了三種不同載體或不同活性組分的催化劑,具體工作如下:(1)金屬-有機(jī)框架化合物(MOFs)是一類(lèi)多孔、比表面積超高的配位聚合物。本文選擇其中結(jié)構(gòu)穩(wěn)定、合成簡(jiǎn)便的ZIF-8作為前驅(qū)體,將其經(jīng)過(guò)焙燒碳化制成氮摻雜的碳結(jié)構(gòu)(NC),其中在950℃下碳化而成的NC-950對(duì)乙炔氫氯化反應(yīng)活性最好。將其用酸進(jìn)行進(jìn)一步改性,發(fā)現(xiàn)經(jīng)王水改性的NC-950活性最高,在GHSV(C_2H_2)為50 h-1,反應(yīng)溫度為180℃時(shí),NC-950)(王水)催化劑的乙炔轉(zhuǎn)化率可達(dá)50%以上,表現(xiàn)出較高的催化活性。且在研究中,經(jīng)XPS表征發(fā)現(xiàn),吡咯型N在反應(yīng)中起明顯的催化作用,且隨著反應(yīng)的進(jìn)行,吡咯型N會(huì)逐漸轉(zhuǎn)化為吡啶型N,使催化效果逐漸降低。(2)以NC-950為載體制備的Au1Cu1/NC-950催化劑和載體為活性炭的Au1Cu1/AC催化劑,在C_2H_2空速為600 h-1、V(HCl):V(C_2H_2)=1.15:1、溫度為180oC的條件下,在20 h內(nèi),Au1Cu1/NC-950催化劑的乙炔轉(zhuǎn)化率維持在90%以上,而Au1Cu1/AC催化劑的乙炔轉(zhuǎn)化率在達(dá)到最高值95%后逐漸下降至68%。可知Au1Cu1/NC-950催化劑活性明顯優(yōu)于Au1Cu1/AC催化劑。其原因是NC-950載體中的N能夠促進(jìn)反應(yīng)氣體C_2H_2在催化劑上的吸附,同時(shí)還能夠誘導(dǎo)活性中心Au與HCl形成Au-Cl鍵,并且發(fā)生極化,從而使催化劑活性增強(qiáng)。(3)S的改性能夠有效提高AuCu/AC催化劑的催化活性。在未用S改性時(shí),活性組分Au NPs和Cu NPs由于其較高的表面能而發(fā)生團(tuán)聚,導(dǎo)致催化劑失活;但經(jīng)S改性后,能夠有效促進(jìn)活性納米粒子的分散,從而減弱了由于團(tuán)聚而導(dǎo)致失活的影響。在C_2H_2空速為180 h-1、V(HCl):V(C_2H_2)=1.15:1、溫度為180 oC的條件下,在長(zhǎng)達(dá)520 h(21天)的時(shí)間里,Au1Cu2-S1/AC催化劑的C_2H_2轉(zhuǎn)化率及VCM選擇性均保持在99%以上,且未有明顯的下降趨勢(shì)。此外,S的加入能夠使活性炭載體層狀分離,使其比表面積增大,有效提升了催化劑的活性及穩(wěn)定性。
[Abstract]:Vinyl chloride (VCM) is a monomer that produces polyvinyl chloride (PVC), an important chemical product. China accounts for more than 60 per cent of the world's annual production of more than 40 million tons of PVC. Based on the energy status of rich coal, lean oil and less gas in China, over 75% of PVC in China is produced by acetylene hydrochlorination with coal as raw material. At present, more than 70 countries and territories worldwide have signed the Minamata Convention, which provides for a ban on the production, import and export of mercury-containing products from 2020 in all countries that have signed the Convention, Therefore, the research and development of new and effective mercury-free catalysts is an urgent problem in PVC production industry. In this paper, three kinds of catalysts with different supports or active components are studied. The main works are as follows: (1) Metallic organic framework compounds (MOFs) are a kind of porous coordination polymers with high specific surface area. In this paper, ZIF-8, which has stable structure and simple synthesis, is selected as precursor, and calcined to form nitrogen-doped carbon structure (NC). NC-950, which is carbonized at 950 鈩，

本文編號(hào)：2137961