铜基、镍基催化剂非均相催化生物质甘油制备乳酸及动力学研究

发布时间：2018-07-21 18:31

【摘要】：伴随社会的迅速发展,能源的消耗量与日俱增,传统化石能源能量储备有限,不可避免的将加速化石能源消耗殆尽。化石能源的过度利用导致了地球环境极度恶化,因此寻求绿色可再生清洁能源已经迫在眉睫。通过甲醇与动物植物油脂之间进行的酯交换生成的生物柴油作为可再生能源的代表,目前已经大规模量生产并应用,这是因为其可再生性、对化石能源的可替代性以及可以减少温室气体排放,减少污染提高空气质量。然而随着生物柴油用量激增,副产物甘油也会大量生产。因此,开发由甘油出发制备更具价值的化学品引起相关研究人员的注意。其中生物质甘油转化制备乳酸是甘油重要的利用途径,因为乳酸可以作为多种生物可降解材料以及生物相容材料的前体。所以催化转化甘油制备乳酸具有重要的理论研究、环境效益和经济价值。本文主要研究了碱性载体负载金属铜,金属纳米铜以及石墨负载镍等为催化剂,以生物质甘油为原料,NaOH为碱源,催化制备乳酸。在反应过程中探究了各实验参数如甘油浓度、NaOH浓度、实验温度、实验时间及催化剂量等反应因素对催化剂催化效果的影响,研究了催化剂结构与催化活性的构效关系。并以幂指数动力学方程为模型对实验数据进行拟合,进行了催化反应动力学研究。取得研究结果如下。1.采用等孔体积浸渍法,制备了以MgO,ZrO2和HAP(羟基磷灰石)为载体,纳米Cu0为活性组分的负载型铜基催化剂。在高压反应釜中,碱性条件下,以生物质甘油为原料催化制备乳酸。研究发现,具有强碱性位的MgO和HAP载体负载铜催化剂催化效果要高于弱碱强度的载体ZrO2负载铜催化剂。当以Cu(16)/HAP为催化剂,以1.0 mol L~(-1)甘油和1.1 mol L~(-1)的NaOH在230 oC下反应2 h,乳酸选择性可达90%,甘油转化率为91%。同时Cu(16)/HAP表现出很好的重复利用性能。以Cu(16)/HAP为催化剂,使用幂指数动力学模型对甘油浓度,NaOH浓度以及反应温度等对反应的影响进行了评价,催化反应活化能(Ea)为117.2 kJ mol L~(-1)。2.采用湿化学还原法,使用不同化学结构的有机修饰剂制备了不同粒径的纳米铜。当以聚乙二醇为修饰剂制备的具有最小粒径的纳米铜催化剂催化转化甘油制备乳酸时,其表现出很好的催化性能。以1.0 mol L~(-1)甘油和1.1 mol L~(-1)的NaOH为反应物,在230 oC下反应4 h,甘油转化率为98.0%,乳酸选择性为91.9%。以CuPEG(36.9 nm)和Cublank(118.3 nm)为催化剂,反应活化能分别为76.3和86.5 kJ mol L~(-1)。纳米铜粒径的降低明显降低了反应活化能,加速了催化反应。3.在NaOH水溶液中,超细石墨负载的镍催化剂有效地催化甘油制备乳酸。研究发现,NaOH和镍纳米颗粒协同催化甘油制备乳酸。当甘油浓度为1.0 mol L~(-1),NaOH浓度为1.1 mol L~(-1),以Ni0.3/石墨为催化剂,在230 oC反应3 h,反应物转化率和主产物选择性分别为97.6%和92.2%。反应活化能(Ea)为69.2 kJ mol L~(-1)。研究表明,铜基、镍基催化剂具有良好的催化甘油制备乳酸活性,以生物质甘油为原料催化制备乳酸具有替代传统糖类发酵制备乳酸的可行性。
[Abstract]:With the rapid development of the society, the consumption of energy is increasing, the energy reserves of the traditional fossil energy are limited and the fossil energy will inevitably be depleted. The overutilization of fossil energy leads to the extreme deterioration of the earth's environment. Therefore, it is imminent to seek green renewable clean energy. Biodiesel generated by transesterification, as a representative of renewable energy, is now produced and applied with large moduli because of its renewability, substitutes for fossil fuels, reducing greenhouse gas emissions, reducing pollution and improving air quality. However, as the amount of biodiesel increases, the byproduct glycerol is also The development of a more valuable chemical from glycerol, therefore, has attracted the attention of relevant researchers. The conversion of biomass glycerin to lactic acid is an important use of glycerol, because lactic acid can be used as a precursor of biodegradable materials and biocompatible materials. It has important theoretical research, environmental benefit and economic value. In this paper, the basic carrier load metal copper, metal nanoscale copper and graphite loaded nickel are used as the catalyst, the biomass glycerol as the raw material and the NaOH as the base source, the lactic acid is prepared. In the reaction process, the experimental parameters such as glycerol concentration, NaOH concentration, and experimental temperature are explored. The influence of the reaction time and the amount of catalyst on the catalytic activity of the catalyst was studied. The structure effect relationship of the catalyst structure and the catalytic activity was studied. The experimental data were fitted with the power exponent kinetic equation as the model, and the catalytic reaction kinetics was studied. The results are as follows:.1. is prepared by the impregnation method of equal pore volume. The supported copper based catalyst with MgO, ZrO2 and HAP (hydroxyapatite) as the carrier and the nano Cu0 as the active component. In the high pressure reactor, the lactic acid was prepared with biomass glycerol as the catalyst under the alkaline condition. It was found that the catalytic effect of the MgO and HAP supported copper catalyst with strong alkali position was higher than the carrier ZrO2 negative of the weak alkali strength. Copper catalyst. When Cu (16) /HAP was used as the catalyst, the NaOH of 1 mol L~ (-1) glycerol and 1.1 mol L~ (-1) were reacted 2 h under 230 oC. The selectivity of lactic acid was 90%. The conversion rate of glycerol was equal to 91%. simultaneously (16). The effect of reaction temperature and the reaction temperature were evaluated. The catalytic activation energy (Ea) was 117.2 kJ mol L~ (-1).2. using wet chemical reduction method. The nano copper with different particle sizes was prepared by the organic modifier of different chemical structures. The nano copper catalyst with the minimum particle size prepared with polyethylene glycol as the modifier was used to catalyze the conversion of glycerol. When the lactic acid was prepared, it showed good catalytic performance. With 1 mol L~ (-1) glycerin and 1.1 mol L~ (-1) NaOH as reactant, the reaction was 4 h under 230 oC, the conversion rate of glycerol was 98%, the selectivity of lactic acid was CuPEG (36.9 nm) and 118.3 (118.3). The reaction activation energy was 76.3 and 86.5, respectively. The reduction obviously reduced the activation energy and accelerated the catalytic reaction.3. in NaOH aqueous solution. The nickel catalyst supported by superfine graphite was used to catalyze the preparation of lactic acid in glycerol effectively. It was found that NaOH and Ni nanoparticles co catalyzed glycerol preparation of lactic acid. The concentration of glycerol was 1 mol L~ (-1), NaOH concentration was 1.1 mol L~ (-1), and Ni0.3/ graphite was used as catalyst. The reaction rate and the selectivity of the main product were 97.6% and the 92.2%. reaction activation energy (Ea) was 69.2 kJ mol L~ (-1) at 230 oC, respectively. The study showed that the copper based catalyst had good catalytic activity for the preparation of lactic acid in glycerol, and the preparation of lactic acid with biomass glycerin as raw material could replace the traditional saccharide fermentation to prepare lactic acid. Feasibility.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ225.4

【参考文献】