固體酸催化環(huán)己酮肟液相Beckmann重排
發(fā)布時間：2018-11-06 16:49
【摘要】：固體酸催化劑是一種新型的環(huán)保催化材料,具有很高的催化活性、良好的選擇性、低腐蝕性、易回收循環(huán)使用的特點,隨著環(huán)保意識和綠色化學理念的不斷加深,環(huán)境友好型的綠色催化工藝技術受到了越來越多的重視。將固體酸催化劑應用于環(huán)己酮肟液相Beckmann重排中,不僅可以緩解催化劑的結焦,延長催化劑的壽命,又能實現(xiàn)催化劑與反應液的迅速分離,對開發(fā)環(huán)境友好的己內酰胺生產(chǎn)工藝具有十分重要的意義。本文制備了四種類型的固體酸催化劑,對其進行了表征分析,催化環(huán)己酮肟液相Beckmann重排,并對催化劑的活性中心、重排產(chǎn)物的生成歷程進行了探究。本文首先采用沉淀-浸漬法合成了硫酸化氧化鋯S-ZrO_2,對其進行了傅里葉紅外、熱重、吡啶吸附紅外和NH3-TPD等表征分析,并將其應用于液相Beckmann重排中。結果表明,由于S-ZrO_2的比表面太小,其對環(huán)己酮肟的活性很低,但SO42-與Zr形成的酸性位利于己內酰胺的生成。除環(huán)己酮外,體系中主要副產(chǎn)物是環(huán)己酮肟的縮聚產(chǎn)物、聚合產(chǎn)物和己內酰胺的縮聚產(chǎn)物,而環(huán)己酮肟聚合生成的水會進一步水解環(huán)己酮肟生成環(huán)己酮。其次,采用MFI結構的沸石分子篩為載體,先向其中摻入雜原子Zr,再用硫酸浸漬,使Zr與SO42-結合形成類似超強酸的結構,制備出硫酸化鋯硅分子篩S-ZS,并考察其催化液相Beckmann重排的性能。結果表明,Zr原子的摻入和硫酸功能化都能增加催化劑對環(huán)己酮肟的活性,增加對己內酰胺的選擇性并減少對環(huán)己酮的選擇性。S-ZS的強酸中心生成的己內酰胺更難脫附,易進一步反應生成高沸點產(chǎn)物,其催化環(huán)己酮肟Beckmann重排反應的副產(chǎn)物種類和體系中水的生成途徑與S-ZrO_2相同。進一步采用模板離子交換法和原位合成法制備了兩種含鋁分子篩TIE-MCM-41和SA20-MCM-41,對兩種催化劑進行了表征,對比了兩種分子篩催化Beckmann重排的結果,并對結果的差異進行了分析。結果表明,相對于Si-MCM-41,由于兩種含鋁分子篩的酸總量增加,對環(huán)己酮肟的活性都有提高。TIE-MCM-41對己內酰胺的選擇性提高的原因是Al的摻入后使得B酸略有增加且硅羥基的酸強度減弱酸量減小所致,SA20-MCM-41對己內酰胺的選擇性最高是由于其B酸含量最高且呈弱酸性的鄰式硅羥基含量的減少進一步抑制了環(huán)己酮的生成。本文最后采用后接枝方法和原位合成方法制備了磺酸功能化的介孔分子篩M-SO3H-P6和M-SO3H-Y,對兩種催化劑進行了表征,并對比了兩種催化劑對Beckmann重排催化性能上的差異。結果表明,相對于純硅MCM-41,由于磺酸基團的引入增加了催化劑的強酸中心,兩種方法合成的磺酸功能化材料都對環(huán)己酮肟的活性都有所提高。原位磺酸功能化MCM-41的B酸含量大于后接枝磺酸功能化MCM-41,并且前者幾乎不含表面硅羥基,抑制了環(huán)己酮肟的水解,對己內酰胺的選擇性更高。
[Abstract]:Solid acid catalyst is a new type of environmental protection catalytic material, with high catalytic activity, good selectivity, low corrosion, easy to recycle and recycling. With the deepening of environmental awareness and green chemical idea, solid acid catalyst is a new type of environmental protection catalyst, which is characterized by its high catalytic activity, good selectivity, low corrosion and easy recycling. More and more attention has been paid to the environmental friendly green catalytic technology. The application of solid acid catalyst in liquid phase Beckmann rearrangement of cyclohexanone oxime can not only alleviate the coking of the catalyst, prolong the life of the catalyst, but also realize the rapid separation of the catalyst from the reaction liquid. It is of great significance to develop environmental friendly caprolactam production process. In this paper, four types of solid acid catalysts were prepared, characterized and analyzed to catalyze the liquid phase Beckmann rearrangement of cyclohexanone oxime. The active sites of the catalysts and the formation process of the rearrangement products were investigated. In this paper, the sulfated zirconia S-ZrO _ 2 was synthesized by precipitation-impregnation method and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), pyridine adsorption infrared (IR) and NH3-TPD, and was applied to the liquid phase Beckmann rearrangement. The results show that the activity of S-ZrO_2 to cyclohexanone oxime is very low due to its small specific surface, but the acidic site formed by SO42- and Zr is favorable to the formation of caprolactam. In addition to cyclohexanone, the main by-products in the system are the condensation products of cyclohexanone oxime, the polymerization products and the condensation products of caprolactam, and the water produced by the polymerization of cyclohexanone oxime will further hydrolyze cyclohexanone oxime to cyclohexanone. Secondly, zeolite molecular sieve with MFI structure was used as carrier, then mixed with heteroatom Zr, and impregnated with sulfuric acid, Zr and SO42- were combined to form superacid-like structure, and S-ZS molecular sieve was prepared. The catalytic properties of Beckmann rearrangement in liquid phase were investigated. The results showed that the addition of Zr atom and the functionalization of sulfuric acid could increase the activity of cyclohexanone oxime, increase the selectivity of caprolactam and decrease the selectivity of cyclohexanone. It was more difficult to desorption caprolactam from the strong acid center of S-ZS. It is easy to react further to form high boiling point products, which catalyze the Beckmann rearrangement of cyclohexanone oxime and the way of water formation in the system is the same as that of S-ZrO_2. Two aluminum-containing molecular sieve TIE-MCM-41 and SA20-MCM-41, were prepared by template ion exchange method and in situ synthesis method. The results of Beckmann rearrangement catalyzed by two molecular sieves were compared. The difference of the results is analyzed. The results showed that compared with Si-MCM-41, the total acid content of the two aluminum-containing molecular sieves increased, The activity of cyclohexanone oxime was improved. The reason for the increase of TIE-MCM-41 selectivity to caprolactam was the slight increase of B acid and the decrease of acid content of silica hydroxyl group due to the addition of Al. The highest selectivity of SA20-MCM-41 to caprolactam is due to the decrease of the hydroxyl content of ortho-silica with the highest B acid content and weak acidity, which further inhibits the formation of cyclohexanone. Finally, M-SO3H-P6 and M-SO3H-Ywere prepared by post-grafting and in-situ synthesis. The two catalysts were characterized. The difference of catalytic performance between the two catalysts for Beckmann rearrangement was also compared. The results showed that compared with pure silicon MCM-41, the activity of cyclohexanone oxime was increased by both the sulfonic acid functional materials synthesized by the two methods because of the addition of sulfonic groups. The B acid content of in situ sulfonic acid functionalized MCM-41 is higher than that of post graft sulfonic acid functionalized MCM-41, and the former has almost no surface silica hydroxyl, which inhibits the hydrolysis of cyclohexanone oxime and has higher selectivity for caprolactam.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36;TQ236
[Abstract]:Solid acid catalyst is a new type of environmental protection catalytic material, with high catalytic activity, good selectivity, low corrosion, easy to recycle and recycling. With the deepening of environmental awareness and green chemical idea, solid acid catalyst is a new type of environmental protection catalyst, which is characterized by its high catalytic activity, good selectivity, low corrosion and easy recycling. More and more attention has been paid to the environmental friendly green catalytic technology. The application of solid acid catalyst in liquid phase Beckmann rearrangement of cyclohexanone oxime can not only alleviate the coking of the catalyst, prolong the life of the catalyst, but also realize the rapid separation of the catalyst from the reaction liquid. It is of great significance to develop environmental friendly caprolactam production process. In this paper, four types of solid acid catalysts were prepared, characterized and analyzed to catalyze the liquid phase Beckmann rearrangement of cyclohexanone oxime. The active sites of the catalysts and the formation process of the rearrangement products were investigated. In this paper, the sulfated zirconia S-ZrO _ 2 was synthesized by precipitation-impregnation method and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), pyridine adsorption infrared (IR) and NH3-TPD, and was applied to the liquid phase Beckmann rearrangement. The results show that the activity of S-ZrO_2 to cyclohexanone oxime is very low due to its small specific surface, but the acidic site formed by SO42- and Zr is favorable to the formation of caprolactam. In addition to cyclohexanone, the main by-products in the system are the condensation products of cyclohexanone oxime, the polymerization products and the condensation products of caprolactam, and the water produced by the polymerization of cyclohexanone oxime will further hydrolyze cyclohexanone oxime to cyclohexanone. Secondly, zeolite molecular sieve with MFI structure was used as carrier, then mixed with heteroatom Zr, and impregnated with sulfuric acid, Zr and SO42- were combined to form superacid-like structure, and S-ZS molecular sieve was prepared. The catalytic properties of Beckmann rearrangement in liquid phase were investigated. The results showed that the addition of Zr atom and the functionalization of sulfuric acid could increase the activity of cyclohexanone oxime, increase the selectivity of caprolactam and decrease the selectivity of cyclohexanone. It was more difficult to desorption caprolactam from the strong acid center of S-ZS. It is easy to react further to form high boiling point products, which catalyze the Beckmann rearrangement of cyclohexanone oxime and the way of water formation in the system is the same as that of S-ZrO_2. Two aluminum-containing molecular sieve TIE-MCM-41 and SA20-MCM-41, were prepared by template ion exchange method and in situ synthesis method. The results of Beckmann rearrangement catalyzed by two molecular sieves were compared. The difference of the results is analyzed. The results showed that compared with Si-MCM-41, the total acid content of the two aluminum-containing molecular sieves increased, The activity of cyclohexanone oxime was improved. The reason for the increase of TIE-MCM-41 selectivity to caprolactam was the slight increase of B acid and the decrease of acid content of silica hydroxyl group due to the addition of Al. The highest selectivity of SA20-MCM-41 to caprolactam is due to the decrease of the hydroxyl content of ortho-silica with the highest B acid content and weak acidity, which further inhibits the formation of cyclohexanone. Finally, M-SO3H-P6 and M-SO3H-Ywere prepared by post-grafting and in-situ synthesis. The two catalysts were characterized. The difference of catalytic performance between the two catalysts for Beckmann rearrangement was also compared. The results showed that compared with pure silicon MCM-41, the activity of cyclohexanone oxime was increased by both the sulfonic acid functional materials synthesized by the two methods because of the addition of sulfonic groups. The B acid content of in situ sulfonic acid functionalized MCM-41 is higher than that of post graft sulfonic acid functionalized MCM-41, and the former has almost no surface silica hydroxyl, which inhibits the hydrolysis of cyclohexanone oxime and has higher selectivity for caprolactam.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36;TQ236
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