多组多钴基催化剂催化硼氢化钠制氢技术的研究

发布时间：2019-02-13 13:14

【摘要】：燃料电池作为一种高效洁净的发电装置,其发展受到了各国政府的高度重视。以高纯氢气作为燃料应用于燃料电池时,其催化剂具有催化稳定性强、产电效率高、产电能力强等优点,被视为高温条件下燃料电池理想燃料的首选。NaBH4水解／醇解产氢技术具有储氢量高、制取氢气纯度高、环境友好、产氢过程方便可控等优点,是目前广为探讨的供氢技术之一。常温条件下的NaBH4水解产氢需要在催化剂氛围下进行,目前制备出的催化剂普遍都受成本高、对环境要求苛刻、催化稳定性差和再生能力弱等问题的制约,不利于大规模实际应用。因此,开发廉价、稳定性强、抗毒性强的过渡金属催化剂应用于NaBH4催化水解／醇解制氢,对NaBH4直接水解燃料电池的应用都具有非常重要的理论价值和实际意义。本论文对廉价高效过渡金属催化剂在醇／水溶液和实际水体中的产氢进行研究,主要研究内容和结果如下： 1、以过渡金属Ni、Fe、Cu和稀土金属Y、Ce和La作为助催化剂,考察了钴基催化剂催化NaBH4水解制氢过程的催化性能,实验发现助催化剂掺杂量对催化活性存在一最佳范围,Ni、Fe、Cu、Y、Ce和La等助剂含量的最佳值分别为20%、20%、10%、30%、30%和30%。当助催化剂处于最佳值时,各催化剂的催化活性依次为NiYCuLaCeFe无助剂。各催化剂所对应的催化反应活化能值按大小依次为：FeCeLaCuY。Co-Fe-B/At催化剂活化能最大的为64.85kJ/mol; Co-Y-B/At催化剂活化能最小为35.69kJ/mol; 2、考查了NaBH4在醇／水混合液产氢过程中醇／水体积比对产氢过程的影响,发现产氢速率随醇／水体积比的升高先增大后降低,当醇／水体积比保持为75%时产氢速率最高,产生这种现象的原因可能是：催化剂对于乙醇和水电离出的-OH存在离子竞争吸附过程。由于水中的O-H键更容易极化,可以优先与催化剂颗粒表面接触,而乙醇由于-CH3基团诱导的疏水性,使其减缓了乙醇中的O-H键与催化剂表面的接触,降低了产氢速率。同时,在乙醇溶液的生成产物中NaB(OH)4溶于水中会增大溶液的粘度,抑制反应物离子向催化剂表面、产物离子从催化剂表面向液相的扩散,也降低了产氢速率； 3、系统地考察了以Ti02、凹凸棒石和硅胶为载体的多组分催化剂的催化性能,实验发现按照催化活性由大到小的排列顺序为：Ti02凹凸棒石硅胶,平均产氢速率分别为6.84L/(min.g、2.89L/(min.g)和2.39L/(min.g)。通过多次循环实验考查了负载型催化剂的催化稳定性,结果表明以凹凸棒石为载体的催化剂催化稳定性较好,10次循环实验后催化活性降低为初始时的75%,而以Ti02为载体的催化剂在10次循环实验后活性降低为初始的29.27%； 4、考查了NaBH4浓度、NaOH浓度和催化剂中Y含量等因素对Co-Y-B/Ti02催化剂催化产氢速率的影响,三者对产氢速率均存在最佳范围,分别是8%、8%和30%；活性组分负载量和反应温度均对产氢速率呈正相关作用。通过分析以Ti02、凹凸棒和硅胶作为载体的Co-Y-B催化剂的催化行为,建立了一级催化反应动力学模型,它们在NaBH4醇／水解过程中的催化反应均符合一级反应动力学模型； 5、以采集的天然河水作为溶剂进行产氢实验时,对应的平均产氢速率低于蒸馏水产氢速率,反应过程中包括NaBH4浓度、NaOH浓度、反应温度等因素对产氢过程的影响同蒸馏水体系类似；河水中Ca(HCO3)2、CaCl2和NaHCO3等盐成分对产氢过程有较大影响,而KCl、、MgSO4、Na2SO4和NaCl等盐成分对产氢速率影响很小;通过响应面分析可优化NaBH4浓度、NaOH浓度、反应温度、载体种类和Y添加量等5个因素得到平均产氢速率的最佳值,回归得到二次方程模型,该模型预测值与实验数据误差较小,实验模型可靠。
[Abstract]:As an efficient and clean power generation device, the fuel cell is highly valued by governments. The catalyst has the advantages of strong catalytic stability, high production efficiency, strong electric capacity and the like when the high pure hydrogen is used as the fuel, and is regarded as the first choice for the ideal fuel of the fuel cell under the high-temperature condition. NaBH4 hydrolysis/ alcoholysis hydrogen production technology has the advantages of high hydrogen storage capacity, high purity of the prepared hydrogen, environment-friendly, convenient and controllable hydrogen production process and the like, and is one of the widely explored hydrogen supply technologies. The production of hydrogen by NaBH4 under normal temperature needs to be carried out under the atmosphere of a catalyst, and the currently prepared catalyst is generally subject to the problems of high cost, severe environmental requirements, poor catalytic stability and weak regeneration capacity, and is not conducive to large-scale practical application. Therefore, it has very important theoretical value and practical meaning to the application of the transition metal catalyst with low cost, high stability and strong anti-toxicity to NaBH4 catalytic hydrolysis/ alcohol solution for hydrogen production. This paper studies the hydrogen production of cheap and efficient transition metal catalyst in the alcohol/ water solution and the actual water, and the main contents and results are as follows: Lower: 1, with transition metal Ni, Fe, Cu and rare earth metals Y, Ce and La as co-active agents The catalytic performance of the catalytic NaBH4 hydrolysis hydrogen production process of the cobalt-based catalyst was investigated. The experimental results show that the optimum range of the co-catalyst doping amount to the catalytic activity is 20%, 20%, 10%, 30%, 30%, respectively. When the co-catalyst is at the optimum value, the catalytic activity of each catalyst is NiYCuLaCeFe. The activation energy of the catalytic reaction corresponding to each catalyst is as follows: the activation energy of the FeCeLaCuY. Co-Fe-B/ At catalyst is the maximum of 64. 85kJ/ mol; the activation energy of the Co-Y-B/ At catalyst is at least 35. 69kJ/ mol. in mol; 2, that alcohol/ water volume ratio of NaBH4 in the hydrogen production process of the alcohol/ water mixture is investigated to produce hydrogen. The effect of the process is that the hydrogen production rate decreases with the increase of the alcohol/ water volume ratio, and the hydrogen production rate is the highest when the alcohol/ water volume ratio is maintained at 75%. because the O-H bond in the water is more easily polarized, the surface of the catalyst particles can be preferentially contacted with the surface of the catalyst particles, and the ethanol is reduced by the hydrophobicity induced by the-CH3 group, so that the contact and the reduction of the O-H bond in the ethanol and the surface of the catalyst are reduced, In addition, NaB (OH) 4 in the product of the ethanol solution is dissolved in water to increase the viscosity of the solution, inhibit the reaction of the reactant ions to the surface of the catalyst, and the diffusion of the product ions from the surface of the catalyst to the liquid phase is also reduced. a hydrogen-producing rate; a systematic examination. The catalytic performance of multi-component catalyst supported by Ti02, attapulgite and silica gel was investigated. The results showed that the average hydrogen production rate was 6.84L/ (min. g, 2.89L/ (min. g) and 2.39L/ (min. g) and 2.39L/ (min. g) and 2.39L/ (min. g) and 2.39L/ (min. g) respectively. The catalytic stability of the supported catalyst was investigated by multiple cycle experiments. The results show that the catalytic stability of the catalyst with attapulgite as the carrier is good, and the catalytic activity after 10 cycles is reduced to 75% of the initial time, while the activity of the catalyst with Ti02 as the carrier was reduced to an initial activity after 10 cycles The effects of NaBH4 concentration, NaOH concentration and Y content in the catalyst on the hydrogen production rate of Co-Y-B/ Ti02 catalyst were investigated. The optimum range is 8%, 8% and 30%, respectively, and the loading and reaction temperature of the active component are the same. The catalytic behavior of Co-Y-B catalyst supported by Ti02, attapulgite and silica gel was analyzed, and the first-order catalytic reaction kinetic model was established. The catalytic reaction in the process of NaBH4 alcohol/ hydrolysis was met. First level and 5, when the natural river water collected is used as a solvent to produce hydrogen production experiments, the corresponding average hydrogen production rate is lower than that of the distilled water, and the influence of factors such as NaBH4 concentration, NaOH concentration, reaction temperature and the like on the hydrogen production process is similar to that of the distilled water system; and the river The salt components such as Ca (HCO3) 2, CaCl 2 and NaHCO3 in water have a great effect on the hydrogen production process, and the salt components such as KCl, MgSO4, Na2SO4 and NaCl have little effect on the hydrogen production rate, and the NaBH4 concentration can be optimized by the response surface analysis. 5 factors such as NaOH concentration, reaction temperature, carrier type and Y addition amount are obtained to obtain the optimum value of the average hydrogen production rate, and the regression is obtained by the quadratic equation model, and the model prediction value and the experimental data
【学位授予单位】：青岛科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM911.4;TQ116.2

【参考文献】