三氧化钨纳米材料制备及其对纤维素加氢催化研究
发布时间：2019-04-30 17:45
【摘要】：世界经济的高速发展使得化石能源的消耗飞速增长,其不可再生性导致石化燃料的紧缺,而且会造成严重的环境污染,使得人们越来越关注可再生清洁能源的开发利用。在各种各样的可再生清洁能源(风能、太阳能、地热能等)中,生物质能是唯一能够固定碳转化为直接化工产品的清洁可再生能源。生物质中最重要的组成成分是纤维素,利用纤维素生产多元醇能源燃料主要分为两步,首先水解成葡萄糖或者纤维二糖,然后催化加氢制备多元醇,这种工艺操作较为复杂,反应间隔时间较长。因此开发高效的催化剂,改进合成工艺,对催化纤维素水解加氢一步制备多元醇有重要的现实价值。本文以微晶纤维素为原料,Ru/WO3负载型化合物为催化剂,水为介质,高温高压条件下采用一锅法将纤维素进行催化加氢液化。在选择催化剂制备试验中,选择了 W基催化剂。采用无有机添加剂的水热合成法制备WO3纳米片,利用NaBH4还原法制得一系列过渡金属/WO3负载型催化剂,同样方法制备体相WO3负载型催化剂。通过XRD、Raman、TEM、XPS和H2-TPR等表征手段研究了负载型催化剂的性能。结果表明贵金属Ru与WO3纳米片相互作用良好,结构稳定,且Ru分散均匀,对纤维素液化的催化性能好。在纤维素催化加氢条件优化的实验中,采用单因素实验法,以纤维素转化率和乙二醇产率为目标,探讨了贵金属负载量、反应温度、反应时间和初始氢压对纤维素液化的影响规律。结果表明纤维素催化加氢液化的最佳制备工艺条件为:纤维素1.0g,1%Ru/WO3催化剂0.25g,40mL水,反应温度为240℃,初始氢压为4MPa,反应时间为2h。在此反应条件下,纤维素的转化率为100%,乙二醇的选择性为76.3%。另外为了测试催化剂的稳定性,通过重复性实验表明,Ru/WO3负载型催化剂的重复利用率高。采用气相色谱等检测手段对液化产物进行分析。结果表明,无催化剂时纤维素的加氢产物主要是山梨醇和甘露醇等糖醇,添加了催化剂后,反应主要产物是乙二醇。通过一系列物理/化学表征手段,提出贵金属Ru和载体WO3之间存在着电子交互反应。另外RuOxδ+纳米粒子的存在一方面释放氢离子到溶液中水解纤维素,另一方面将WO3还原成WO3-x,对Ru/WO3催化剂体系催化降解纤维素得乙二醇的反羟醛缩合反应机理做出详细解释。
[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，
本文编号：2468917
[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，
本文编号：2468917
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