亞臨界水中廢棄鑄型尼龍非均相催化降解的研究
發(fā)布時(shí)間：2018-08-06 19:58
【摘要】：鑄型尼龍(Monomer casting nylon,MC尼龍)是一種優(yōu)質(zhì)的聚酰胺類工程塑料,但伴隨著相關(guān)制品應(yīng)用需求的增長(zhǎng),廢棄的MC尼龍對(duì)環(huán)境保護(hù)及資源再利用的壓力也在與日俱增。在眾多廢棄材料的再資源化方法中,亞臨界水技術(shù)由于具有傳質(zhì)性能好、擴(kuò)散系數(shù)高以及來(lái)源綠色等特質(zhì),在聚合物材料的回收領(lǐng)域中擁有巨大的應(yīng)用潛力。然而在現(xiàn)有的聚酰胺類材料水解的研究工作中,缺乏對(duì)降解具體反應(yīng)過(guò)程和提高降解效率技術(shù)的詳細(xì)分析�；谝陨媳尘�,本文研究了廢棄MC尼龍?jiān)趤喤R界水中的降解反應(yīng),并通過(guò)引入不同類型的非均相催化劑實(shí)現(xiàn)了提高水解反應(yīng)效率、降低能耗并避免二次污染的目標(biāo)。本文在無(wú)催化劑添加的條件下對(duì)MC尼龍水解的反應(yīng)產(chǎn)物進(jìn)行了定性分析,并在此基礎(chǔ)上進(jìn)一步研究了影響水解度和單體產(chǎn)率的主要因素。在完善MC尼龍水解反應(yīng)過(guò)程的研究后,進(jìn)而提出了其在亞臨界水中的降解機(jī)理。MC尼龍?jiān)趤喤R界水環(huán)境中可以完全降解為水溶性低聚物和單體己內(nèi)酰胺(ε-caprolactam,CPL)。在其水解過(guò)程中,原料完全降解之前的固相殘余物為未分解完全的尼龍,隨著水解的進(jìn)行殘余MC尼龍的含量逐漸減少,熱穩(wěn)定性不斷下降,顆粒尺寸也隨水解時(shí)間的增加持續(xù)減小。作為水解反應(yīng)的中間產(chǎn)物,水溶性的環(huán)狀及線型低聚物在液相中通過(guò)進(jìn)一步的斷鏈及脫水反應(yīng)生成目標(biāo)單體CPL。通過(guò)低聚物的逐步解聚反應(yīng),單體CPL在345℃亞臨界水中的最高產(chǎn)率可達(dá)85%以上。為了提高水解效率并克服傳統(tǒng)均相催化劑分離困難和嚴(yán)重腐蝕設(shè)備等弊端,本文從來(lái)源廣泛、制備簡(jiǎn)易、綠色環(huán)保等方面考慮,制備了γ-Al_2O_3負(fù)載型固體酸催化劑并評(píng)價(jià)了它們?cè)贛C尼龍水解反應(yīng)中的催化性能。研究發(fā)現(xiàn),在此系列非均相催化劑中,SO_4~(2-)/ZrO_2/γ-Al_2O_3(AZS1)固體酸催化劑由于酸性較強(qiáng),對(duì)MC尼龍的降解催化效果最為顯著。當(dāng)水解反應(yīng)條件為溫度320℃、時(shí)間30 min時(shí),使用AZS1可使MC尼龍水解度由無(wú)催化反應(yīng)時(shí)的28%增加至51%,單體CPL產(chǎn)率提高4倍以上。根據(jù)反應(yīng)過(guò)程及單體增長(zhǎng)趨勢(shì)研究,本文建立了由兩個(gè)連續(xù)的一級(jí)反應(yīng)步驟組成的動(dòng)力學(xué)模型。通過(guò)動(dòng)力學(xué)分析顯示,與無(wú)催化反應(yīng)相比,AZS1可有效提升不同水解步驟的反應(yīng)速率常數(shù)并降低其表觀活化能。高效穩(wěn)定的非均相催化劑能夠與亞臨界水技術(shù)協(xié)同實(shí)現(xiàn)廢棄聚合物材料的高產(chǎn)出低投入式回收,而固體酸AZS1的循環(huán)使用能力有待提高,所以本文選取并研究了水熱穩(wěn)定性較好的H型沸石分子篩在MC尼龍水解反應(yīng)中的催化行為。在一系列不同孔道結(jié)構(gòu)的沸石分子篩中,H-Beta-25分子篩由于較大的孔徑及豐富的強(qiáng)酸位點(diǎn)展現(xiàn)了最為優(yōu)異的催化水解性能。在同樣的水解條件下(320℃,30 min)時(shí),單體產(chǎn)率與無(wú)催化反應(yīng)相比可以提高7倍以上,甚至優(yōu)于固體酸AZS1。MC尼龍的酸催化水解遵循正碳離子反應(yīng)機(jī)理,但是具有不同結(jié)構(gòu)的催化劑所對(duì)應(yīng)的催化水解進(jìn)程略有差異。與AZS1相比,H-Beta-25沸石分子篩主要通過(guò)提高特定結(jié)構(gòu)中間產(chǎn)物的形成與消耗速度來(lái)促進(jìn)MC尼龍的水解。此外H-Beta-25在水熱環(huán)境中催化性能更為穩(wěn)定,是一種較為理想的聚酰胺材料水解用非均相催化劑。
[Abstract]:Monomer casting nylon (MC nylon) is a high quality Polyamide Engineering plastic, but with the increasing demand for related products, the pressure of waste MC nylon on environmental protection and resource reuse is increasing day by day. In the reresource method of many waste materials, the subcritical water technology has the mass transfer performance. Well, high diffusion coefficient and green source have great potential for application in the field of polymer recovery. However, in the current research work on the hydrolysis of polyamide materials, the detailed analysis of the specific degradation process and the technology of improving the degradation efficiency is lack. Based on the above background, the waste MC nylon is studied in this paper. The degradation reaction of subcritical water was carried out by introducing different types of heterogeneous catalysts to improve the efficiency of hydrolysis, reduce energy consumption and avoid two times of pollution. In this paper, the product of hydrolysis of MC nylon was qualitatively analyzed under the condition of no catalyst addition, and on this basis, the hydrolysis of hydrolysis was further studied. The main factors of degree and monomer yield. After improving the hydrolysis process of MC nylon, the degradation mechanism of.MC nylon in subcritical water can be completely degraded into water-soluble oligomers and monomer caprolactam (epsilon -caprolactam, CPL) in the subcritical water environment. As the residual MC nylon content decreases gradually with the hydrolysis, the thermal stability decreases and the particle size decreases with the increase of hydrolysis time. As the intermediate product of the hydrolysis reaction, the water-soluble ring and linear oligomers are in the liquid phase through further chain breaking and dehydration reaction. The maximum yield of monomer CPL in subcritical water at 345 degrees centigrade can reach more than 85% through gradual depolymerization of oligomer CPL.. In order to improve hydrolysis efficiency and overcome the disadvantages of traditional homogeneous catalyst separation and serious corrosion equipment, this paper has prepared gamma -Al_2O_3 from a wide range of sources, preparation and green environmental protection. The catalytic performance of the supported solid acid catalysts in the hydrolysis of MC nylon was evaluated. It was found that, in this series of heterogeneous catalysts, SO_4~ (2-) /ZrO_2/ gamma -Al_2O_3 (AZS1) solid acid catalyst has the most remarkable catalytic effect on the degradation of MC nylon because of its strong acidity. When the hydrolysis reaction conditions are 320 C, 30 min time. The use of AZS1 can increase the degree of hydrolysis of MC nylon from 28% to 51% and increase the yield of monomer CPL by 4 times. Based on the reaction process and the growth trend of the monomer, a kinetic model composed of two successive first order reactions is established. The dynamic analysis shows that AZS1 can be effective compared with the non catalytic reaction. The reaction rate constant of different hydrolysis steps is improved and its apparent activation energy is reduced. The high efficiency and stable heterogeneous catalyst can be used in collaboration with subcritical water technology to achieve high yield and low input recovery of waste polymer materials, while the recycling ability of solid acid AZS1 needs to be improved. The catalytic behavior of H zeolite molecular sieves in the hydrolysis of MC nylon. In a series of different pore structure zeolite molecular sieves, H-Beta-25 molecular sieves exhibit the most excellent catalytic hydrolysis performance due to the larger pore size and rich acid sites. Under the same hydrolysis conditions (320, 30 min), the monomer yield and the non catalytic reaction Compared with the solid acid AZS1.MC nylon, the acid catalyzed hydrolysis follows the mechanism of the positive carbon ion reaction, but the catalytic hydrolysis process corresponding to the catalysts with different structures is slightly different. Compared with AZS1, H-Beta-25 zeolite molecular sieve is mainly by improving the formation and consumption rate of the intermediate products of the specific structure. In addition, H-Beta-25 is more stable in hydrothermal environment and is an ideal heterogeneous catalyst for hydrolysis of polyamide.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：X705;O643.32
本文編號(hào)：2168830
[Abstract]:Monomer casting nylon (MC nylon) is a high quality Polyamide Engineering plastic, but with the increasing demand for related products, the pressure of waste MC nylon on environmental protection and resource reuse is increasing day by day. In the reresource method of many waste materials, the subcritical water technology has the mass transfer performance. Well, high diffusion coefficient and green source have great potential for application in the field of polymer recovery. However, in the current research work on the hydrolysis of polyamide materials, the detailed analysis of the specific degradation process and the technology of improving the degradation efficiency is lack. Based on the above background, the waste MC nylon is studied in this paper. The degradation reaction of subcritical water was carried out by introducing different types of heterogeneous catalysts to improve the efficiency of hydrolysis, reduce energy consumption and avoid two times of pollution. In this paper, the product of hydrolysis of MC nylon was qualitatively analyzed under the condition of no catalyst addition, and on this basis, the hydrolysis of hydrolysis was further studied. The main factors of degree and monomer yield. After improving the hydrolysis process of MC nylon, the degradation mechanism of.MC nylon in subcritical water can be completely degraded into water-soluble oligomers and monomer caprolactam (epsilon -caprolactam, CPL) in the subcritical water environment. As the residual MC nylon content decreases gradually with the hydrolysis, the thermal stability decreases and the particle size decreases with the increase of hydrolysis time. As the intermediate product of the hydrolysis reaction, the water-soluble ring and linear oligomers are in the liquid phase through further chain breaking and dehydration reaction. The maximum yield of monomer CPL in subcritical water at 345 degrees centigrade can reach more than 85% through gradual depolymerization of oligomer CPL.. In order to improve hydrolysis efficiency and overcome the disadvantages of traditional homogeneous catalyst separation and serious corrosion equipment, this paper has prepared gamma -Al_2O_3 from a wide range of sources, preparation and green environmental protection. The catalytic performance of the supported solid acid catalysts in the hydrolysis of MC nylon was evaluated. It was found that, in this series of heterogeneous catalysts, SO_4~ (2-) /ZrO_2/ gamma -Al_2O_3 (AZS1) solid acid catalyst has the most remarkable catalytic effect on the degradation of MC nylon because of its strong acidity. When the hydrolysis reaction conditions are 320 C, 30 min time. The use of AZS1 can increase the degree of hydrolysis of MC nylon from 28% to 51% and increase the yield of monomer CPL by 4 times. Based on the reaction process and the growth trend of the monomer, a kinetic model composed of two successive first order reactions is established. The dynamic analysis shows that AZS1 can be effective compared with the non catalytic reaction. The reaction rate constant of different hydrolysis steps is improved and its apparent activation energy is reduced. The high efficiency and stable heterogeneous catalyst can be used in collaboration with subcritical water technology to achieve high yield and low input recovery of waste polymer materials, while the recycling ability of solid acid AZS1 needs to be improved. The catalytic behavior of H zeolite molecular sieves in the hydrolysis of MC nylon. In a series of different pore structure zeolite molecular sieves, H-Beta-25 molecular sieves exhibit the most excellent catalytic hydrolysis performance due to the larger pore size and rich acid sites. Under the same hydrolysis conditions (320, 30 min), the monomer yield and the non catalytic reaction Compared with the solid acid AZS1.MC nylon, the acid catalyzed hydrolysis follows the mechanism of the positive carbon ion reaction, but the catalytic hydrolysis process corresponding to the catalysts with different structures is slightly different. Compared with AZS1, H-Beta-25 zeolite molecular sieve is mainly by improving the formation and consumption rate of the intermediate products of the specific structure. In addition, H-Beta-25 is more stable in hydrothermal environment and is an ideal heterogeneous catalyst for hydrolysis of polyamide.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：X705;O643.32
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