Studies of the Effect of Pressure in Membrane Reactors

膜反应器中压力影响的研究

• 批准号: 0622666
• 负责人: S. Ted Oyama
• 金额: $ 15万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-10-01 至 2008-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0622666&HistoricalAwards=false
• 关键词: Studies; Effect; Pressure; Membrane; Reactors

Abstract Proposal Title: Studies of the Effect of Pressure in Membrane Reactors, Proposal Number: CTS-0622666, Principal Investigator: Ted S. Oyama, Institution: Virginia Polytechnic Institute and State University Abstract:This project deals with the study of advanced membranes and membrane reactors for enhancing the performance of catalytic systems by coupling of transport and reaction processes. The specific reaction to be examined will be the oxygen-assisted, autothermal reforming of methane for producing hydrogen. This is an attractive reaction because the use of oxygen allows the simultaneous operation of the exothermic combustion reaction and the endothermic reforming reaction which leads to efficient heat utilization. In addition oxygen prevents catalyst deactivation by coke formation. The studies are made possible by our recent development of inorganic membranes that combine high hydrogen permeance (5 x 10-7 mol m-2s-1Pa-1), selectivity ( 1500), stability ( 500 h) and inertness at high pressure and temperature. The membranes are tubular composites consisting of a base support made of porous a -alumina with graded layers of a alumina substrate, and a topmost thin layer (30 nm) of silica. They are prepared by a combination of sol processing and chemical vapor deposition (CVD). The current permeance of the membranes exceeds that of pure Pd, but we will undertake research to improve the permeance significantly. This will be done in two ways. First, by optimizing the pore size of the intermediate graded layer derived from the boehmite sols through control of the particle size and thickness of the layers. Second, by engineering the composition of the topmost layer by using mixed-element CVD. This latter work will be guided by ab initio DFT calculations. We have successfully obtained activation energies for passage of molecules through model Si ring structures that match those of actual permeation data. We plan to carry out a theoretical combinatorial screening of a wide variety of compositions that include metals (Y, Zr, Ti, etc.), nonmetals (B, Al, etc.), and lanthanides (La, Ce, etc.) to guide the experimental work. The membrane reactor studies on the autothermal reforming will be carried out at high pressure (20-30 atm) and will include measurement of the kinetics of the reaction and the description of the reactor with 1-d (longitudinal) and 2-d (longitudinal and radial) mathematical models. A major goal is to investigate the transition regime between 1-d and 2-d descriptions and to develop criteria for the applicability of the models that can be used for general reactions. The reactor studies will also explore the feasibility of overcoming pressure drop losses across the membrane in a novel manner: by harnessing the increase in moles of the reaction itself.The broader impacts of the project are substantial. The topic of the research, autothermal reforming is important in the energy and chemicals area, addressing the efficient utilization of natural gas. The developments in the silica membrane preparation will also find applicability in other areas such as zeolite or oxygen conduction membranes. The research will provide advanced training for graduate students in a broad discipline that includes experimental and theoretical aspects so as to stimulate creative thinking. Importantly, great emphasis will be placed on the involvement of women, minority and undergraduate students by active recruitment. A substantive collaboration will be initiated with a faculty member from a local undergraduate school (Radford Univ.) to promote personal growth of the individual, as well as to stimulate the participation of students from that school in higher education.

摘要提案标题：膜反应器中压力效应的研究，提案编号：CTS-0622666，首席研究员：Ted S.Oyama，机构：弗吉尼亚理工学院和州立大学摘要：这个项目是研究先进的膜和膜反应器，通过传输和反应过程的耦合来提高催化系统的性能。将要考察的具体反应将是甲烷在氧气辅助下的自热重整制氢。这是一个有吸引力的反应，因为氧气的使用允许放热燃烧反应和吸热重整反应同时进行，从而导致高效的热利用。此外，氧气还可以防止催化剂因结焦而失活。我们最近开发的无机膜结合了高氢渗透率(5×10-7molm-2s-1pa-1)、选择性(1500)、稳定性(500h)和在高压和温度下的惰性，使这些研究成为可能。这些膜是管状复合材料，由多孔的α-氧化铝制成的底座与氧化铝衬底的梯度层和最上面的一层(30 Nm)二氧化硅组成。它们是通过溶胶处理和化学气相沉积(CVD)相结合的方法制备的。膜的电流透过率超过纯Pd，但我们将进行研究，以显著提高透过率。这将通过两种方式完成。首先，通过控制薄水铝石溶胶的颗粒大小和厚度来优化中间梯度层的孔径。第二，利用混合元素化学气相沉积来设计最顶层的成分。后一项工作将以从头算密度泛函计算为指导。我们已经成功地获得了分子通过模型硅环结构的激活能，与实际渗透数据相匹配。我们计划对多种成分进行理论组合筛选，包括金属(Y、Zr、Ti等)、非金属(B、Al等)和稀土元素(La、Ce等)。指导试点工作。膜反应器自热重整的研究将在高压(20-30大气压)下进行，将包括反应动力学的测量和用一维(纵向)和二维(纵向和径向)数学模型描述反应器。一个主要的目标是研究一维和二维描述之间的过渡机制，并制定可用于一般反应的模型的适用性标准。反应器研究还将探索以一种新的方式克服跨膜压降损失的可行性：通过利用反应本身摩尔数的增加。该项目的更广泛影响是巨大的。本研究的主题是，自热重整在能源和化工领域具有重要意义，解决了天然气的高效利用问题。二氧化硅膜制备方面的进展也将在其他领域得到应用，如沸石或导氧膜。这项研究将为研究生提供包括实验和理论方面在内的广泛学科的高级培训，以激发创造性思维。重要的是，将非常重视通过积极招聘让妇女、少数民族和本科生参与进来。将与当地一所本科学校(拉德福大学)的一名教职员工展开实质性合作。促进个人的个人成长，以及鼓励该学校的学生参与高等教育。