本文選題：鎳基納米催化劑　切入點：催化加氫　出處：《河北大學(xué)》2017年碩士論文

【摘要】：催化加氫反應(yīng)具有原子經(jīng)濟性的特點,符合綠色化學(xué)化工的發(fā)展要求,是目前國內(nèi)外研究的熱點之一。其中,利用酚類化合物加氫制備相應(yīng)的醇、酮類化合物,可廣泛應(yīng)用于醫(yī)藥、農(nóng)藥、染料等領(lǐng)域。目前,酚類化合物的加氫反應(yīng)均采用鈀等貴金屬催化劑,價格昂貴,且有時還存在原料轉(zhuǎn)化率偏低、目標產(chǎn)物選擇性偏差等問題。針對這些問題,本文首次采用廉價的鎳基納米催化劑用于4-甲氧基苯酚的加氫反應(yīng),研究了不同催化劑結(jié)構(gòu)與活性和穩(wěn)定性之間的關(guān)系,并對4-甲氧基環(huán)己酮合成中氧化反應(yīng)的條件進行了探究。首先,分別采用沉積-沉淀法和浸漬法制備了負載型鎳基納米催化劑Ni/Al_2O_3,并將其應(yīng)用于4-甲氧基苯酚的加氫反應(yīng)�？疾榱藘煞N制備方法及反應(yīng)條件對催化劑活性和穩(wěn)定性的影響。通過X射線衍射(XRD)、H2-程序升溫還原(H2-TPR)及透射電子顯微鏡(TEM)等測試手段對催化劑進行了表征,發(fā)現(xiàn)利用沉積-沉淀法制備的Ni/Al_2O_3-DP催化劑中的活性粒子分散度高、粒徑較小,并且活性粒子與載體之間有較強的相互作用,比浸漬法制備的Ni/Al_2O_3-IMP催化劑具有更好的活性和穩(wěn)定性。接著,為了進一步提高Ni/Al_2O_3-DP的催化活性和穩(wěn)定性,我們通過添加改性金屬制備了一系列Ni-X/Al_2O_3催化劑,并將其應(yīng)用于4-甲氧基苯酚的加氫反應(yīng)。系統(tǒng)研究了改性金屬和反應(yīng)溶劑的極性對催化反應(yīng)活性的影響,重點探究了催化劑結(jié)構(gòu)與穩(wěn)定性之間的關(guān)系。結(jié)果表明Ni-Mg/Al_2O_3催化劑在正己烷中連續(xù)使用27次后,其催化活性基本沒有下降,顯示出了優(yōu)異的穩(wěn)定性。最后,為了提高對目標產(chǎn)物4-甲氧基環(huán)己酮的總選擇性,我們以草酸和鎢酸鈉制備的配合物為催化劑,以雙氧水為氧化劑,對上述加氫反應(yīng)液進行了進一步的氧化,重點考查了氧化條件對4-甲氧基環(huán)己酮總選擇性的影響。結(jié)果表明在最佳的氧化條件下,4-甲氧基環(huán)己酮的總選擇性可達到95.3%,上述研究結(jié)果對于酮類化合物的綠色合成具有較好的借鑒意義。
[Abstract]:Catalytic hydrogenation has the characteristics of atomic economy and meets the requirements of the development of green chemistry and chemical industry, so it is one of the research hotspots at home and abroad, among which, the corresponding alcohols and ketones are prepared by hydrogenation of phenolic compounds. It can be widely used in medicine, pesticide, dye and so on. At present, the hydrogenation of phenolic compounds all use palladium and other noble metal catalysts, the price is expensive, and sometimes the conversion of raw materials is low. In view of these problems, the cheap nickel-based nanocatalysts were used for the hydrogenation of 4-methoxy phenol for the first time. The relationship between the structure of the catalysts and the activity and stability of the catalysts was studied. The conditions of oxidation reaction in the synthesis of 4-methoxy cyclohexanone were studied. The supported Ni / Al _ 2O _ 3 nano-catalyst Ni / Al _ 2O _ 3 was prepared by deposition-precipitation method and impregnation method, and applied to the hydrogenation reaction of 4-methoxy phenol. The activity and stability of two preparation methods and reaction conditions on the catalyst were investigated. The catalyst was characterized by means of X-ray diffraction (XRD) and temperature programmed reduction (TPR) and transmission electron microscopy (TEM). It was found that the active particles in the Ni/Al_2O_3-DP catalyst prepared by deposition-precipitation method had high dispersion, small particle size, and strong interaction between the active particles and the support. In order to further improve the catalytic activity and stability of Ni/Al_2O_3-DP, we prepared a series of Ni-X/Al_2O_3 catalysts by adding modified metal. The effects of the polarity of modified metal and reaction solvent on the catalytic activity of 4-methoxy phenol were systematically studied. The relationship between the structure of the catalyst and the stability of the catalyst was studied. The results showed that the catalytic activity of Ni-Mg/Al_2O_3 catalyst did not decrease after 27 times of continuous use in n-hexane, showing excellent stability. In order to improve the overall selectivity of the target product 4-methoxycyclohexanone, the hydrogenation solution was further oxidized with oxalic acid and sodium tungstate as catalyst and hydrogen peroxide as oxidant. The effects of oxidation conditions on the total selectivity of 4-methoxycyclohexanone were investigated. The results showed that the total selectivity of 4-methoxycyclohexanone could reach 95.33A under the optimum oxidation conditions. The above results were green to ketones. The synthesis has good reference significance.
【學(xué)位授予單位】：河北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;TQ234.21

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