本文選題：甘油 + 氫解��； 參考：《揚州大學(xué)》2017年碩士論文

【摘要】：生物柴油的不斷發(fā)展導(dǎo)致了甘油的大量過剩,將廉價的甘油轉(zhuǎn)化為具有更高附加值的化工產(chǎn)品具有重要的意義。在甘油的衍生物中,1,3-丙二醇具有廣泛的應(yīng)用和較高的市場價值。因此,以生物柴油副產(chǎn)物甘油為原料生產(chǎn)1,3-丙二醇對增加生物柴油產(chǎn)業(yè)的經(jīng)濟效益具有重要的研究意義。本論文采用分步浸漬法分別制備了 WOx促進的Pt/SiO2,Al2O3改性的Pt-WOx/SiO2,硅摻雜的磷酸鋁分子篩SAPO-34負載的Pt-WOx催化劑。論文通過對催化劑的結(jié)構(gòu)、形貌、表面酸性和表面化學(xué)態(tài)等理化性質(zhì)的表征,對其甘油氫解制1,3-丙二醇的催化反應(yīng)性能的測試,來研究催化劑制備方法和其理化性質(zhì)的關(guān)系、催化劑理化性質(zhì)和其催化性能的關(guān)系,揭示甘油在所研究催化劑上的反應(yīng)機理,為甘油氫解制1,3-丙二醇的工業(yè)生產(chǎn)提供基礎(chǔ)數(shù)據(jù)和有益的探索。一、WOx促進的Pt/SiO2催化甘油氫解制1,3-丙二醇本論文采用分步浸漬法制備了不同載體(Zr02、A12O3、Si02)負載的Pt催化劑,同時用WOx對催化劑進行了修飾,考察了載體,WOx前驅(qū)體的焙燒溫度以及WOx的含量對甘油氫解活性的影響,對制得的催化劑通過低溫氮吸附(BJH)、X射線衍射(XRD)、激光共焦拉曼(Raman)、透射電鏡(TEM)、高倍透射電鏡(HRTEM)、X射線光電子能譜(XPS)等測試手段對樣品進行了表征。實驗結(jié)果表明,以Zr02和A1203為載體負載的Pt基催化劑表現(xiàn)出了對C-O鍵較強的斷裂活性,獲得較高的甘油轉(zhuǎn)化率,但是丙二醇的選擇性較低;SiO2負載的催化劑則表現(xiàn)出了相對弱的C-O鍵斷裂活性,具有較低的甘油轉(zhuǎn)化率,但是丙二醇(主要為1,2-丙二醇)的選擇性較高。在Pt/SiO2中摻雜WOx不僅能夠促進Pt/SiO2中氧化態(tài)的Pt還原成金屬Pt,還能夠促進金屬Pt在載體表面的分散,降低金屬Pt顆粒的尺寸。WOx的摻雜也增加了催化劑中弱酸和中強酸酸性位的數(shù)量,促進了 1,3-丙二醇的選擇性生成。因此,WOx的摻雜不僅可以提高催化劑的甘油氫解活性,還可以提高1,3-丙二醇的選擇性,抑制1,3-丙二醇繼續(xù)氫解。高分散的WOx有利于Pt-WOx/SiO2的甘油氫解活性和對1,3-丙二醇的選擇性;結(jié)晶度較好的W03則導(dǎo)致了丙二醇繼續(xù)氫解生成正丙醇。當Pt的質(zhì)量分數(shù)為2%,WOx的質(zhì)量分數(shù)為10%,焙燒溫度為823 K時,Pt-WOx/SiO2催化劑在483 K對甘油的轉(zhuǎn)化率和1,3-丙二醇的選擇性分別為26.0%和21.3%。二、Al2O3促進的Pt-WOx/SiO2催化甘油氫解制1,3-丙二醇本論文采用分步浸漬法制備了 Al2O3促進的Pt-WOx/SiO2催化劑,采用BJH、XRD、Raman、TEM、HRTEM、XPS等技術(shù)手段對樣品進行了表征,研究了 Al2O3前驅(qū)體Al(NO3)3的焙燒溫度以及Al2O3的含量對Pt-WOx/SiO2催化劑的理化性質(zhì)和甘油氫解活性、1,3-丙二醇的選擇性的影響。研究發(fā)現(xiàn),向載體SiO2中摻雜少量的Al2O3能夠增加催化劑表面弱酸酸性位和中強酸酸性位的數(shù)量,并提高了表面酸性的強度,促進了雙功能催化劑Pt-WOx/SiO2-Al2O3的脫水-加氫反應(yīng),加速了甘油氫解和1,3-丙二醇的選擇性產(chǎn)生。Al2O3的摻雜還促進了 WOx的分散,增加SiO2載體表面WOx物種的氧缺陷位的數(shù)量,降低活性金屬Pt的顆粒尺寸,提高了活性組分的分散程度,促進了甘油選擇性氫解生成1,3-丙二醇。當Al2O3的含量為5%,其前驅(qū)體的焙燒溫度為1073 K時,制得的Pt-WOx/SiO2-5%Al2O3(1073 K))催化劑活性最優(yōu),對甘油的轉(zhuǎn)化率和1,3-丙二醇的選擇性分別為46.1%和26.9%。三、Pt-WOx/SAPO-34選擇性氫解甘油制備1,3-丙二醇本論文用分步浸漬法制備了第ⅥB族氧化物(Cr2O3、MoO3、WOx)改性的Pt/SAPO-34,比較了助劑種類和含量對Pt/SAPO-34催化劑的理化性質(zhì)和甘油氫解性能的影響。論文對優(yōu)選的Pt-WOx/SAPO-34催化劑在不同的反應(yīng)溫度、壓力和停留時間的甘油氫解活性進行了測試。結(jié)果表明,第ⅥB族元素中只有W的氧化物對催化劑的甘油氫解活性以及對1,3-丙二醇的選擇性具有積極的作用。摻雜的WOx在催化劑中與載體之間表現(xiàn)出較強的相互作用,具有很高的分散程度。摻雜WOx催化劑表面酸性增加,Pt顆粒更加分散,甘油氫解活性和對1,3-丙二醇的選擇性提高。當WOx的質(zhì)量分數(shù)為20%時(Pt-20%WOx/SAPO-34)的活性最優(yōu),對甘油的轉(zhuǎn)化率和對1,3-丙二醇的選擇性分別為48.0%和18.8%。甘油氫解活性隨反應(yīng)溫度越高而增加,但是高的反應(yīng)溫度也加劇了產(chǎn)品丙二醇進一步氫解;高的氫壓有利于1,3-丙二醇的選擇性生成。然而,較長的反應(yīng)時間會導(dǎo)致催化劑部分失活�？傊�,Si02擔載的Pt-WOx催化劑具有比Al2O3和ZrO2擔載的催化劑更高的甘油氫解活性和1,3-丙二醇的選擇性,其中WOx通過提高催化劑的表面酸性,促進金屬Pt的分散和還原,顯著提高了金屬Pt活性組分的分散程度,從而促進了甘油的轉(zhuǎn)化和1,3-丙二醇的選擇性生成;通過向Pt-WOx/SiO2催化劑中摻雜Al2O3促進了 WOx的分散,增加WOx物種中氧缺位的數(shù)量,降低金屬Pt顆粒的尺寸,提高催化劑的甘油氫解活性和1,3-丙二醇的選擇性;第ⅥB族氧化物中,WOx對Pt/SAPO-34催化劑在甘油選擇性氫解反應(yīng)中表現(xiàn)出積極的促進作用,高分散WOx促進了金屬Pt的分散和甘油選擇性生成1,3-丙二醇。在本論文所研究的催化劑中,Al2O3促進Pt-WOx/SiO2催化劑表現(xiàn)出了最佳的催化性能。
[Abstract]:The continuous development of biodiesel leads to a lot of excess glycerin. It is of great significance to convert cheap glycerol into chemical products with higher added value. In the derivatives of glycerol, 1,3- propanediol has extensive application and high market value. Therefore, the production of 1,3- propanediol by using the biodiesel byproduct glycerin as raw material is increasing. The economic benefits of adding biodiesel industry have important research significance. In this paper, WOx promoted Pt/SiO2, Al2O3 modified Pt-WOx/SiO2, and silicon doped aluminum phosphate zeolite SAPO-34 supported Pt-WOx catalyst were prepared by stepwise impregnation. The structure, morphology, surface acidity and surface chemical state of the catalyst were studied in this paper. The characterization of the catalytic properties of the glycerol hydrogenolysis of 1,3- propanediol, the relationship between the preparation method of the catalyst and its physicochemical properties, the relationship between the physicochemical properties of the catalyst and its catalytic properties, and the mechanism of the reaction of glycerol on the catalyst studied, which provides the basis for the industrial production of the glycerol hydrogenolysis of 1,3- propanediol. Data and useful exploration. 1. WOx promoted Pt/SiO2 catalyzed hydrogenolysis of glycerol to 1,3- propanediol in this paper, a Pt catalyst supported by different carriers (Zr02, A12O3, Si02) was prepared by a stepwise impregnation method. At the same time, the catalyst was modified with WOx, and the roasting temperature of the carrier, the WOx precursor and the effect of the content of WOx on the hydrogenolysis activity of glycerol were investigated. The prepared catalysts were characterized by low temperature nitrogen adsorption (BJH), X ray diffraction (XRD), laser confocal Raman (Raman), transmission electron microscopy (TEM), high transmission electron microscopy (HRTEM), X ray photoelectron spectroscopy (XPS) and other testing methods. Experimental results showed that Pt based catalysts supported by Zr02 and A1203 were compared to C-O bonds. The high conversion rate of glycerol was obtained, but the selectivity of propanediol was lower. The SiO2 supported catalyst showed a relatively weak C-O bond activity, with a lower glycerol conversion rate, but the selectivity of propanediol (mainly 1,2- propanediol) was higher. The doping of WOx in Pt/SiO2 not only promoted the oxidation of Pt/SiO2. The reduction of the state of Pt into metal Pt can also promote the dispersion of metal Pt on the surface of the carrier, and the doping of the size.WOx of the metal Pt particles also increases the number of weak acid and strong acid acid sites in the catalyst, and promotes the selective formation of 1,3- propanediol. Therefore, the doping of WOx can not only improve the hydrogenolysis activity of the glycerol in the catalyst, but also can be raised. The selectivity of high 1,3- propylene glycol inhibits the continued hydrogenolysis of 1,3- propanediol. Highly dispersed WOx is beneficial to the glycerol hydrogenolysis activity of Pt-WOx/SiO2 and selectivity to 1,3- propanediol; the good crystallinity W03 leads to the continued hydrogenolysis of propanediol to propanol. When the mass fraction of Pt is 2%, the mass fraction of WOx is 10%, and the calcination temperature is 823 K, Pt-WO The conversion of glycerol to x/SiO2 catalyst and the selectivity of 1,3- propanediol at 483 K were 26% and 21.3%. two respectively. Al2O3 promoted Pt-WOx/SiO2 catalyzed hydrogenolysis of glycerol to 1,3- propanediol, the Pt-WOx/SiO2 catalyst promoted by Al2O3 was prepared by stepwise impregnation, and the samples were carried out by means of BJH, XRD, Raman, shrinkage, etc. The effects of the calcination temperature of Al2O3 precursor Al (NO3) 3 and the content of Al2O3 on the physical and chemical properties of Pt-WOx/SiO2 catalysts and the selectivity of 1,3- propanediol were investigated. The results showed that a small amount of Al2O3 in the carrier SiO2 could increase the number of weak acid acid sites and strong acid acid sites on the surface of the catalyst and raise the amount of the medium strong acid acid sites. The strength of the surface acidity promoted the dehydration and hydrogenation of the bifunctional catalyst Pt-WOx/SiO2-Al2O3, accelerated the doping of glycerol and the selectivity of 1,3- propanediol, and promoted the dispersion of WOx, increased the number of oxygen defects in the WOx species on the SiO2 carrier, reduced the particle size of the active metal Pt, and increased the activity of the active metal Pt. The dispersion of the component promotes the selective hydrogenolysis of glycerol to 1,3- propanediol. When the content of Al2O3 is 5% and the calcination temperature of the precursor is 1073 K, the Pt-WOx/SiO2-5%Al2O3 (1073 K)) catalyst has the best activity, and the selectivity for glycerol conversion and 1,3- propanediol is 46.1% and 26.9%. three respectively, and Pt-WOx/SAPO-34 is selective hydrogenolysis. The preparation of 1,3- propanediol with glycerol in this paper was prepared by stepwise impregnation method for the modified Pt/SAPO-34 of the first B group (Cr2O3, MoO3, WOx). The effects of the type and content of the additives on the physicochemical properties of the Pt/SAPO-34 catalyst and the properties of the glycerol hydrogenolysis were compared. The selected Pt-WOx/ SAPO-34 catalysts were at different reaction temperatures, pressure and residence time. The activity of glycerol hydrogenolysis was tested. The results showed that only W oxide in the sixth B group had positive effect on the glycerol hydrogenolysis activity of the catalyst and the selectivity of 1,3- propanediol. The doped WOx showed strong interaction with the carrier in the catalyst, and had a high degree of dispersion. The doping of WOx catalyst was very high. With the increase of surface acidity, the Pt particles are more dispersed, the hydrogenolysis activity of glycerol and the selectivity to 1,3- propanediol are increased. When the mass fraction of WOx is 20% (Pt-20%WOx/SAPO-34), the conversion rate of glycerol and the selectivity to 1,3- propanediol, respectively, 48% and 18.8%. glycerol, increase with the higher reaction temperature, but high The reaction temperature also aggravates the further hydrogenolysis of the product propanediol; high hydrogen pressure is beneficial to the selective formation of 1,3- propanediol. However, the longer reaction time will lead to partial deactivation of the catalyst. In a word, the Si02 supported Pt-WOx catalyst has higher glycerol hydrogenolysis activity and the selectivity of 1,3- propanediol than the catalysts supported by Al2O3 and ZrO2. By increasing the surface acidity of the catalyst, WOx promoted the dispersion and reduction of metal Pt, significantly increased the dispersion of the active component of the metal Pt, thus facilitated the conversion of glycerol and the selective formation of 1,3- propanediol. By doping Al2O3 to the Pt-WOx/SiO2 catalyst, the dispersion of WOx was promoted and the number of oxygen vacancies in WOx species was increased. The size of metal Pt particles is reduced, the hydrogenolysis activity of the catalyst and the selectivity of 1,3- propanediol are improved. In the sixth B oxide, WOx has a positive effect on the selective hydrogenation of glycerol to Pt/SAPO-34 catalyst. High dispersion WOx promotes the dispersion of metal Pt and the selectivity of glycerol to produce 1,3- propanediol. In the catalyst studied, Al2O3 promoted the Pt-WOx/SiO2 catalyst to exhibit the best catalytic performance.
【學(xué)位授予單位】：揚州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;O623.413

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