【摘要】：氯代烴類物質(zhì)1,1,2-三氯乙烷(TCE)排放會嚴重污染環(huán)境,造成酸雨、溫室效應(yīng)、臭氧層空洞等環(huán)境問題,因此如何處理氯代烴類物質(zhì)是一個重要的課題。一般通過兩類方法處理TCE,一類是直接分解氯代烴類物質(zhì),包括直接焚燒法、催化燃燒法、生物降解法和光催化分解法；另外一類是將這些氯代烴類物質(zhì)轉(zhuǎn)化為有用的化學(xué)品,顯然后者更具有研究價值。目前氯代烴的主要轉(zhuǎn)化形式為加氫脫氯和脫氯化氫,其中催化劑起著重要作用。本論文主要研究氣相裂解1,1,2-三氯乙烷選擇性脫氯化氫的催化劑,設(shè)計并篩選催化性能高、選擇性好的有機胺和Mg基催化劑,分別用于合成1,1-二氯乙烯(1,1-DCE)和順-1,2-二氯乙烯(cis-1,2-DCE)兩種產(chǎn)品,考察了催化劑負載量、預(yù)處理溫度、載體類型等對脫氯化氫效率和選擇性的影響,探明了TCE脫氯反應(yīng)機理和催化劑失活原因。具體內(nèi)容如下：1.研究了有機胺催化劑氣相催化裂解TCE制備1,1-DCE反應(yīng)。1,1-DCE的聚合物PVDC是綠色食品保鮮包裝材料,目前工業(yè)上采用NaOH強堿液的皂化工藝裂解TCE脫氯化氫來生產(chǎn)1,1-DCE,雖然VDC選擇性較高,但會產(chǎn)生大量高鹽有機廢水,因此采用負載型催化劑氣相催化制備1,1-DCE是一個綠色工藝路線。本部分主要考察了負載型五乙烯六胺(PEHA)催化裂解TCE反應(yīng),發(fā)現(xiàn)PEHA/SiO2催化劑得到1,1-DCE選擇性高達98%,且在脫氯過程中保持穩(wěn)定,但TCE轉(zhuǎn)化率從99%迅速下降到10%以下。通過對PEHA/SiO2催化劑上脫氯機理研究,發(fā)現(xiàn)在強堿性的PEHA作用下,TCE消除HCl遵循E2機理,有機胺與原位產(chǎn)生的HCl反應(yīng)生成了較難分解的氯化胺物種,是催化劑失活的主要原因。2.采用浸漬法制備一系列Mg基催化劑,用于氣相催化裂解TCE反應(yīng)。研究表明Mg基催化劑對TCE裂解都有很高的活性,并選擇性生成cis-1,2-DCE.催化劑的活性與Mg負載量有關(guān),與Mg物種前驅(qū)體無關(guān),以Mg(NO3)2·6H2O口MgCl2·6H2O為前驅(qū)體制備的Mg基催化劑活性一致。Mg負載量為10%的催化劑具有最好的活性和穩(wěn)定性,TCE的轉(zhuǎn)化率高達92%, cis-DCE的選擇性高達91%。在反應(yīng)過程中Mg基催化劑表面逐步形成了含氯的Mg物種,Cl/Mg的摩爾比為1：1,進一步表征證明該物種為Mg(OH)Cl,且是TCE脫氯反應(yīng)的的活性物種。
[Abstract]:The emission of chlorinated hydrocarbons (TCEs) will pollute the environment seriously and cause environmental problems such as acid rain, Greenhouse Effect, ozone layer hole and so on. Therefore, how to deal with chlorinated hydrocarbons is an important subject. TCEs are generally treated in two ways, one is the direct decomposition of chlorinated hydrocarbons, including direct incineration, catalytic combustion, biodegradation and photocatalytic decomposition, and the other is the conversion of these chlorinated hydrocarbons into useful chemicals, Obviously the latter has more research value. At present, the main conversion forms of chlorinated hydrocarbons are hydrodechlorination and dehydrochlorination, among which catalysts play an important role. In this paper, the catalyst for selective dehydrochlorination of 1 ~ 1H ~ (2 +) trichloroethane from gas phase cracking was studied, and the organic amines and Mg-based catalysts with high catalytic performance and good selectivity were designed and screened. The effects of catalyst loading, pretreatment temperature and carrier type on the efficiency and selectivity of dehydrochlorination were investigated. The mechanism of TCE dechlorination and the reason of catalyst deactivation were investigated. The details are as follows: 1. The organic amine catalyst was prepared by gas phase catalytic pyrolysis (TCE) to prepare 1 (1-DCE). 1 (1-DCE) polymeric PVDC is a green food packaging material. At present, the saponification process of NaOH strong base solution is used to produce 1H _ (1-DCE) by pyrolysis of TCE, although the selectivity of VDC is high. However, a large amount of high salt organic wastewater will be produced, so it is a green process route to use supported catalyst to catalyze the preparation of 1hl-DCE in gaseous phase. In this part, the catalytic cracking TCE reaction of supported pentaethylenehexamine (PEHA) was investigated. It was found that the selectivity of 1-DCE reached 98% over PEHA / SiO2 catalyst, and remained stable during dechlorination, but the conversion of TCE decreased rapidly from 99% to less than 10%. The mechanism of dechlorination on PEHA / Sio _ 2 catalyst was studied. It was found that the elimination of HCl by TCE followed the E2 mechanism under the action of PEHA / Sio _ 2, and the reaction of organic amine with HCl produced in situ produced more difficult species of amine chloride, which was the main reason for the deactivation of the catalyst. A series of Mg-based catalysts were prepared by impregnation method for gas phase catalytic cracking of TCE. The results show that the Mg-based catalysts have high activity for TCE cracking and selectively produce cis-1n 2-DCE. The activity of the catalyst was related to the amount of mg loaded, but not to the precursor of mg species. Mg (no _ 3) _ (2) 6H _ (2) O was used as the precursor to prepare MgCl _ (2) 6H _ 2O. The catalyst with the same activity and 10% mg loading had the best activity and stability. The conversion of TCE was up to 92%, and the selectivity of cis-DCE was up to 91%. The molar ratio of Cl / mg was 1: 1 on the surface of Mg-based catalyst. It was further characterized that the species was mg (OH) Cl and was an active species for TCE dechlorination.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O643.36

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