本文關(guān)鍵詞： AlOOH 乙醛 分層裝填 低碳醇 水熱法　出處：《太原理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：在前期研究中發(fā)現(xiàn)本課題組自主創(chuàng)新提出的完全液相法制備的CuZn Al催化劑中Al組分是以一種介穩(wěn)相Al OOH的形式存在,而不是以常規(guī)的γ-Al2O3存在。AlOOH是一類結(jié)晶不完整的氧化鋁水合物,具有特殊的雙層結(jié)構(gòu)。AlOOH具有界面自由能高、孔隙率和比表面積大、分散性好的特點。目前,AlOOH主要用于γ-Al2O3前驅(qū)體的制備,作為吸附劑和負(fù)載型催化劑載體,以其為催化劑鮮有報道。前期課題組單獨制備了AlOOH,將其與工業(yè)甲醇合成催化劑C302機(jī)械混合用于CO加氫反應(yīng),產(chǎn)物中出現(xiàn)選擇性較高的C2+OH,但其作用機(jī)理尚不明確。為了探究AlOOH的催化作用,本文采用水熱法制備了幾種不同結(jié)構(gòu)的AlOOH,將其用于甲醇與CO或合成氣反應(yīng),考察了AlOOH結(jié)構(gòu)對反應(yīng)性能的影響,推測AlOOH可能的作用機(jī)理。以此為基礎(chǔ)進(jìn)一步選用不同方法制備了AlOOH,并將其與C302復(fù)合分層裝填用于CO加氫反應(yīng),考察了不同制備方法對CO加氫反應(yīng)性能的影響,主要得出以下結(jié)論:1.常壓下AlOOH用于催化甲醇與CO或合成氣反應(yīng),AlOOH對CO活化能力極弱而對甲醇脫水能力較強(qiáng)。同時通入甲醇與合成氣會影響AlOOH對甲醇的吸附,進(jìn)而影響其轉(zhuǎn)化率。2.壓力對AlOOH催化甲醇與CO或合成氣反應(yīng)產(chǎn)物分布存在顯著影響。常壓下產(chǎn)物以二甲醚和烴類為主,高壓(4 MPa)下以乙醛和二甲醚為主。表征結(jié)果表明催化劑結(jié)晶度高、具有較大孔徑、對CO發(fā)生解離吸附且表面具有適宜酸堿性有利于乙醛的生成。3.根據(jù)表征和活性評價結(jié)果推測乙醛的生成是通過CH3與HCO中間體的偶聯(lián)完成的,證實AlOOH具有碳鏈增長作用。4.不同制備方法會顯著影響AlOOH的結(jié)構(gòu)及復(fù)合催化劑的產(chǎn)物分布。經(jīng)過水熱處理的AlOOH結(jié)晶度提高,層狀結(jié)構(gòu)完整,表面酸性發(fā)生明顯改變�；钚宰詈煤虲2+OH選擇性最優(yōu)的催化劑與其晶形完整、擇優(yōu)取向晶面明顯,具有適宜比例的強(qiáng)弱酸位和強(qiáng)弱堿位的協(xié)同作用密切相關(guān)。5.催化劑的不同裝填方式對催化劑性能影響顯著,機(jī)械混合較分層復(fù)合更有利于C2+OH的生成,說明AlOOH與CuZn組分的協(xié)同作用對C2+OH的生成存在一定的影響。
[Abstract]:In previous studies, it was found that Al component in the CuZn Al catalyst prepared by the complete liquid phase method proposed by our group was in the form of a metastable Al OOH. Instead of using conventional 緯 -Al2O3, AlOOH is a kind of alumina hydrate with incomplete crystallization. It has special double layer structure. AlOOH has high interface free energy, high porosity and large specific surface area. At present, AlOOH is mainly used in the preparation of 緯 -Al _ 2O _ 3 precursor, which is used as adsorbent and supported catalyst carrier. AlOOH was prepared separately and mechanically mixed with commercial methanol synthesis catalyst C302 for CO hydrogenation. In order to investigate the catalytic action of AlOOH, several AlOHs with different structures were prepared by hydrothermal method, which were used in the reaction of methanol with CO or syngas. The effect of AlOOH structure on the reaction performance was investigated, and the possible mechanism of AlOOH action was speculated. Based on this, AlOOHs were prepared by different methods, and were mixed with C302 for CO hydrogenation. The effects of different preparation methods on the performance of CO hydrogenation were investigated. The main conclusions are as follows: 1. Under atmospheric pressure, AlOOH is used to catalyze the reaction between methanol and CO or syngas. AlOOH has very weak activation ability to CO and strong dehydration ability to methanol. At the same time, adding methanol and syngas will affect the adsorption of AlOOH to methanol. The pressure has a significant effect on the distribution of the products of the reaction between methanol and CO or syngas catalyzed by AlOOH. The main products under atmospheric pressure are dimethyl ether and hydrocarbons. Acetaldehyde and dimethyl ether are the main catalysts at high pressure (4MPa). The characterization results show that the catalyst has high crystallinity and large pore size. The dissociation and adsorption of CO and suitable acidity and alkalinity on the surface are beneficial to the formation of acetaldehyde. According to the results of characterization and activity evaluation, it is inferred that the formation of acetaldehyde is accomplished by the coupling of CH3 and HCO intermediates. It is proved that AlOOH has the function of carbon chain growth. 4. The structure of AlOOH and the product distribution of the composite catalyst can be significantly affected by different preparation methods. The crystallinity of AlOOH after hydrothermal treatment is increased and the layered structure is intact. The surface acidity changed obviously. The catalyst with the best activity and the best selectivity of C 2OH was integrated with its crystal shape, and the preferred orientation crystal plane was obvious. The synergistic effects of strong and weak acid sites and strong weak base sites are closely related to each other. 5. The different loading modes of catalysts have a significant effect on the performance of the catalysts, and mechanical mixing is more favorable to the formation of C 2OH than stratified compounding. The results show that the synergistic effect of AlOOH and CuZn on the formation of C 2OH has a certain effect on the formation of C 2OH.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36

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