發(fā)布時(shí)間：2018-04-14 07:11

  本文選題：H_4Nb_6O_(17)納米管 + 固體酸��； 參考：《安徽理工大學(xué)》2017年碩士論文

【摘要】：作為重要的有機(jī)化合物,乙酸正丁酯是一重要的精細(xì)化工產(chǎn)品,它由乙酸與正丁醇在酸催化作用下通過酯化反應(yīng)獲得。通常用硫酸作為催化劑,雖然催化劑活性高,但存在產(chǎn)品難分離,腐蝕設(shè)備,廢水污染環(huán)境等問題。固體酸可以克服硫酸帶來的這些問題,而且擁有表面強(qiáng)酸性、選擇性好、無污染等優(yōu)點(diǎn),因此固體酸作為催化劑取代液體酸已得到了廣泛的研究,且發(fā)展?jié)摿�巨大。本文通過高溫固相法合成K4Nb6O17前驅(qū)體,經(jīng)過質(zhì)子交換、剝離、溶膠-溶膠復(fù)合、酸沉積、焙燒、硫酸浸漬等途徑對(duì)其進(jìn)行改性獲得鈮基復(fù)合固體酸材料,采用XRD、HRTEM、N2吸附-脫附、Raman、FT-IR、NH3-TPD等技術(shù)對(duì)本文所制備樣品的理化性質(zhì)進(jìn)行表征和分析,并以乙酸正丁醇的酯化反應(yīng)來評(píng)價(jià)它們的酸催化活性,通過比較得出酸催化活性最高的固體酸催化劑為SO42--ZrO2@NT-Nb2O5(1:3,0.5)復(fù)合材料。研究結(jié)果表明:納米管NT-H4Nb6O17材料是由片層H4Nb6017自卷曲形成,且其具有較大的比表面積182 m2·g-1和孔體積0.46 cm3·g-1,管徑均勻且管長(zhǎng)較長(zhǎng)。使用硫酸浸漬處理使NT-H4Nb6O17材料的比表面積、酸強(qiáng)度和酸量都有所增加,且硫酸濃度越大,增加的越明顯。復(fù)合材料的形貌與復(fù)合物中Zr與Nb的摩爾比有關(guān),當(dāng)Zr:Nb摩爾比為1:3時(shí),復(fù)合材料具有納米管結(jié)構(gòu),而Zr:Nb摩爾比為1:2時(shí)復(fù)合材料呈現(xiàn)片狀結(jié)構(gòu)。ZrO2氧化物粒子分散在層板的表面,改變了層板表面的應(yīng)力,當(dāng)復(fù)合比例增大時(shí),層板不再能自我卷曲形成納米管。與NT-H4Nb6O17材料相比,復(fù)合材料的比表面積和孔體積均減小。硫酸浸漬增加了復(fù)合材料的比表面積、酸強(qiáng)度以及酸量,且硫酸濃度越大,增加的越明顯。選擇一定的酯化反應(yīng)條件,以乙酸正丁醇的酯化反應(yīng)來評(píng)價(jià)NT-H4Nb6017材料及其改性材料的酸催化活性,結(jié)果顯示SO42--ZrO2@NT-Nb205(1:3,0.5)復(fù)合材料呈現(xiàn)較好的酸催化活性。選擇乙酸正丁醇的摩爾比、反應(yīng)溫度、反應(yīng)時(shí)間、催化劑用量四種因素作為試驗(yàn)考察因素指標(biāo),同時(shí)對(duì)每個(gè)因素取三個(gè)水平進(jìn)行正交設(shè)計(jì),考察SO42--ZrO2@Nb2O5(1:3,0.5)復(fù)合材料對(duì)乙酸正丁醇酯化反應(yīng)的催化活性。試驗(yàn)結(jié)果表明:在最優(yōu)方案下,酯化率高達(dá)90.3%,這主要?dú)w功于其納米管結(jié)構(gòu)、較高的酸量以及較強(qiáng)的酸性。并對(duì)SO42--ZrO2@Nb2O5(1:3,0.5)復(fù)合材料進(jìn)行單因素優(yōu)化試驗(yàn),從而獲得最佳的反應(yīng)條件。
[Abstract]:As an important organic compound, n-butyl acetate is an important fine chemical product, which is obtained by the esterification of acetic acid and n-butanol in the presence of acid.Sulfuric acid is usually used as catalyst, although the catalyst activity is high, but there are some problems such as product separation, corrosion equipment, wastewater pollution and so on.Solid acid can overcome these problems caused by sulfuric acid, and has the advantages of strong acidity, good selectivity, no pollution and so on. Therefore, solid acid as a catalyst to replace liquid acid has been widely studied and has great potential for development.In this paper, the K4Nb6O17 precursor was synthesized by high temperature solid state method. It was modified by proton exchange, stripping, sol-sol composite, acid deposition, roasting and sulfuric acid impregnation to obtain niobium based composite solid acid material.The physicochemical properties of the samples prepared in this paper were characterized and analyzed by means of XRDX HRTEMN _ 2 adsorption-desorption technique, such as Ramann FT-IRN NH _ 3-TPD, and their acid catalytic activity was evaluated by esterification of n-butanol acetate.By comparison, the solid acid catalyst with the highest acid catalytic activity is SO42-ZrO2NT-Nb2O5 (1: 30.5) composite material.The results show that the nanotube NT-H4Nb6O17 material is formed by the self-crimp of H4Nb6017 lamellar, and it has a large specific surface area of 182 m2 g ~ (-1) and pore volume of 0.46 cm3 g ~ (-1). The diameter of the nanotube is uniform and the length of the tube is longer.The specific surface area, acid strength and acid content of NT-H4Nb6O17 materials were increased by sulfuric acid impregnation, and the higher the sulfuric acid concentration was, the more obvious the increase was.The morphology of the composite is related to the molar ratio of Zr to NB in the composite. When the molar ratio of Zr:Nb is 1:3, the composite has nanotube structure, while the composite exhibits a flake structure. ZrO 2 oxide particles are dispersed on the surface of the laminates when the molar ratio of Zr:Nb is 1:2.The stress on the surface of the laminates is changed. When the composite ratio increases, the laminates can no longer curl themselves to form nanotubes.Compared with NT-H4Nb6O17, the specific surface area and pore volume of the composites are reduced.Sulfuric acid impregnation increased the specific surface area, acid strength and acid content of the composites, and the higher the sulfuric acid concentration, the more obvious the increase.The acid catalytic activity of NT-H4Nb6017 and its modified materials was evaluated by esterification of n-butanol acetate under certain esterification conditions. The results showed that SO42-ZrO2NT-NT-Nb205- 1: 30.5) composite showed better acid catalytic activity.Four factors, the molar ratio of n-butanol acetate, reaction temperature, reaction time and the amount of catalyst, were selected as the index of the experimental investigation, and the orthogonal design was carried out at three levels of each factor.The catalytic activity of so _ 42--ZrO _ 2 @ NB _ 2O _ 5 / 1: 3O _ (0.5) composite for the esterification of n-butanol acetate was investigated.The experimental results show that the esterification rate is as high as 90.3% under the optimal scheme, which is mainly attributed to its nanotube structure, high acid content and strong acidity.The single factor optimization test of so _ 42--ZrO _ 2 @ NB _ 2O _ 5 / 1: 3O _ (0.5) composite was carried out, and the optimum reaction conditions were obtained.
【學(xué)位授予單位】：安徽理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;TQ225.24

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