【作者】 冯冬梅；

【导师】 王金福； 王德峥；

【作者基本信息】 清华大学 ， 化学工程与技术， 2009， 博士

【摘要】 氢能以其清洁、高效、可再生被视为本世纪最具发展潜力的能源,目前基于化学过程的移动制氢装置的研究开发,已成为当前燃料电池领域的热点课题之一,二甲醚由于其清洁环保特性成为燃料电池电动汽车的理想氢源之一。对二甲醚水蒸汽重整制氢(DME SR)过程的研究也引起研究者的关注,与其它制氢原料相比,二甲醚具有高能量密度、无毒、氢含量高、储运方便、制氢条件温和等优点,其储存和运输可与现存液化石油气的设施兼容,适用于移动制氢或小型氢源制氢。二甲醚水蒸汽重整制氢不仅扩展了二甲醚在燃料方面的应用领域,而且有利于环境保护,其工艺兼有能源和环保双重意义。本文通过热力学模拟计算,确认了二甲醚水蒸汽重整制氢过程的热力学可行性。通过实验探讨了固体酸及铜基催化剂的组成对二甲醚重整复合催化剂性能的影响。二甲醚水解需较强的酸性中心,筛选出的ZSM-5(25)是最适宜的水解催化剂。采用改进的共沉淀法制备出性能良好的甲醇水蒸汽重整催化剂Cu-Zn-Al-Zr (CD501)。为实现二甲醚水解反应与甲醇水蒸汽重整反应的耦合,研制了CD501/Z(25)复合催化剂,评价得其活性和选择性均明显优于其它复合催化剂。在固定床反应器中,用优化的催化剂全面地考察了各种工艺条件对二甲醚水蒸汽重整过程反应性能的影响,根据二甲醚水蒸汽重整反应在固定床反应器中的实验数据,回归得到了二甲醚重整反应过程的动力学参数;并将其应用到二甲醚重整制氢过程的模拟计算过程中,取得了良好的效果。在膜反应器中,研究纯氢和混合气体条件下氢的渗透规律,将钯银合金膜反应器应用于二甲醚水蒸汽重整反应中,实现水蒸汽重整反应和富氢气体分离净化等单元设计成一体化,实现催化反应与产物分离过程的耦合。采用实验与模拟计算相结合的方法全面系统地研究了各种工艺条件对二甲醚水蒸汽重整制氢过程的影响,总结分析了膜反应器中该催化反应过程的特性规律。本研究结果为更详细的研究二甲醚水蒸汽重整制氢反应过程提供了重要的参考依据。更多还原

【Abstract】 Hydrogen is a fuel that is regarded as having the most development potential for this century because of its clean, efficient, and renewable characteristics. The use of hydrogen gas in mobile fuel cell has led to a wide interest in the development of technology for on-board H2 production from liquid fuels, e.g., catalytic steam reforming (SR) of dimethyl ether (DME) to produce H2. Among the various hydrocarbon feeds, DME has the advantages of high energy density, non-toxicity, easy availability, safe handling/storage, and that the infrastructure in place for LPG distribution can be readily adapted for DME.In this work, the thermodynamics of hydrogen production from DME SR was analyzed to evaluate its feasibility. The type and acidic amount of a solid acid and the composition of a copper-based catalyst were studied to understand their role in the catalytic reactions. DME hydrolysis needs strong acid centers and DME hydrolysis catalysts were studied. ZSM-5(25) was selected as the most suitable solid acid catalyst because it had a strong acidity that gave a high activity in DME hydrolysis. A new methanol SR catalyst Cu-Zn-Al-Zr, codenamed CD501, was developed by optimization of the preparation method. ZSM-5(25) was used together with CD501 as a physical solid mixture to form a bifunctional catalyst for the DME SR reaction, and showed a higher catalytic activity and thermal stability than the traditional catalysts. A synergy of the coupled DME hydrolysis reaction and methanol SR reaction gave a high one-pass DME conversion and the energy consumption was also less.After the catalyst system for the process was optimized, DME SR experiments in a fixed bed reactor were carried out to study the effects of the operating conditions. The reaction kinetic parameters for the catalyzed reactions in the process were obtained by regression from experimental results and their use in the simulation of the DME reforming process achieved good results.In a membrane reactor (MR), hydrogen permeation through a palladium-silver membrane was investigated in the presence of pure hydrogen and gas mixture of hydrogen and other reaction and product components. A palladium-silver alloy membrane reactors was used to carry out DME SR by preforming both reaction and hydrogen separation in the same device. Experiment and simulation of hydrogen production process using a MR were performed. The reactor and catalyst performance data presented can provide fundamental data for a DME SR process design.更多还原