【摘要】：世界經(jīng)濟(jì)的高速發(fā)展使得化石能源的消耗飛速增長,其不可再生性導(dǎo)致石化燃料的緊缺,而且會(huì)造成嚴(yán)重的環(huán)境污染,使得人們越來越關(guān)注可再生清潔能源的開發(fā)利用。在各種各樣的可再生清潔能源(風(fēng)能、太陽能、地?zé)崮艿?中,生物質(zhì)能是唯一能夠固定碳轉(zhuǎn)化為直接化工產(chǎn)品的清潔可再生能源。生物質(zhì)中最重要的組成成分是纖維素,利用纖維素生產(chǎn)多元醇能源燃料主要分為兩步,首先水解成葡萄糖或者纖維二糖,然后催化加氫制備多元醇,這種工藝操作較為復(fù)雜,反應(yīng)間隔時(shí)間較長。因此開發(fā)高效的催化劑,改進(jìn)合成工藝,對(duì)催化纖維素水解加氫一步制備多元醇有重要的現(xiàn)實(shí)價(jià)值。本文以微晶纖維素為原料,Ru/WO3負(fù)載型化合物為催化劑,水為介質(zhì),高溫高壓條件下采用一鍋法將纖維素進(jìn)行催化加氫液化。在選擇催化劑制備試驗(yàn)中,選擇了 W基催化劑。采用無有機(jī)添加劑的水熱合成法制備WO3納米片,利用NaBH4還原法制得一系列過渡金屬/WO3負(fù)載型催化劑,同樣方法制備體相WO3負(fù)載型催化劑。通過XRD、Raman、TEM、XPS和H2-TPR等表征手段研究了負(fù)載型催化劑的性能。結(jié)果表明貴金屬Ru與WO3納米片相互作用良好,結(jié)構(gòu)穩(wěn)定,且Ru分散均勻,對(duì)纖維素液化的催化性能好。在纖維素催化加氫條件優(yōu)化的實(shí)驗(yàn)中,采用單因素實(shí)驗(yàn)法,以纖維素轉(zhuǎn)化率和乙二醇產(chǎn)率為目標(biāo),探討了貴金屬負(fù)載量、反應(yīng)溫度、反應(yīng)時(shí)間和初始?xì)鋲簩?duì)纖維素液化的影響規(guī)律。結(jié)果表明纖維素催化加氫液化的最佳制備工藝條件為:纖維素1.0g,1%Ru/WO3催化劑0.25g,40mL水,反應(yīng)溫度為240℃,初始?xì)鋲簽?MPa,反應(yīng)時(shí)間為2h。在此反應(yīng)條件下,纖維素的轉(zhuǎn)化率為100%,乙二醇的選擇性為76.3%。另外為了測試催化劑的穩(wěn)定性,通過重復(fù)性實(shí)驗(yàn)表明,Ru/WO3負(fù)載型催化劑的重復(fù)利用率高。采用氣相色譜等檢測手段對(duì)液化產(chǎn)物進(jìn)行分析。結(jié)果表明,無催化劑時(shí)纖維素的加氫產(chǎn)物主要是山梨醇和甘露醇等糖醇,添加了催化劑后,反應(yīng)主要產(chǎn)物是乙二醇。通過一系列物理/化學(xué)表征手段,提出貴金屬Ru和載體WO3之間存在著電子交互反應(yīng)。另外RuOxδ+納米粒子的存在一方面釋放氫離子到溶液中水解纖維素,另一方面將WO3還原成WO3-x,對(duì)Ru/WO3催化劑體系催化降解纖維素得乙二醇的反羥醛縮合反應(yīng)機(jī)理做出詳細(xì)解釋。
[Abstract]:With the rapid development of the world economy, the consumption of fossil energy increases rapidly. Its non-renewable nature leads to the shortage of fossil fuels and serious environmental pollution, which makes people pay more and more attention to the development and utilization of renewable clean energy. Among all kinds of renewable clean energy (wind, solar, geothermal, etc.), biomass energy is the only clean renewable energy that can convert fixed carbon into direct chemical products. Cellulose is the most important component in biomass. The energy fuel for the production of polyol from cellulose is divided into two steps: first hydrolysis to glucose or cellulose disaccharide, and then catalytic hydrogenation to produce polyol. This process is very complicated. The reaction interval was longer. Therefore, the development of efficient catalysts and the improvement of synthesis process are of great practical value for one-step preparation of polyols by hydrolysis and hydrogenation of cellulose. In this paper, microcrystalline cellulose was used as raw material, Ru/WO3 supported compound as catalyst, water as medium, under high temperature and high pressure, cellulose was hydrogenated and liquefied by one-pot method. W-based catalyst was selected in the preparation test of selective catalyst. WO3 nanoparticles were prepared by hydrothermal synthesis without organic additives. A series of transition metal / WO3 supported catalysts were prepared by NaBH4 reduction method. Bulk WO3 supported catalysts were prepared by the same method. The performance of the supported catalyst was studied by XRD,Raman,TEM,XPS and H2-TPR. The results show that the noble metal Ru interacts well with WO3 nanoparticles, and the structure is stable, and the Ru dispersion is uniform, and the catalytic activity for cellulose liquefaction is good. In the experiment of optimizing the conditions of catalytic hydrogenation of cellulose, the conversion of cellulose and the yield of ethylene glycol were studied by single factor experiment, and the load of precious metal and the reaction temperature were discussed. Effects of reaction time and initial hydrogen pressure on cellulose liquefaction. The results showed that the optimum preparation conditions were as follows: cellulose 1.0 g, 1%Ru/WO3 catalyst 0.25 g, water 40 mL, reaction temperature 240 鈩，

本文編號(hào)：2468917