CAREER: Designing Partial Oxidation Catalysts for Selective Gas Microsensors

摘要提案编号：0644707主要分析师：Baertsch，Chelsey机构：普渡大学有一个能够检测和量化的碳氢化合物和挥发性有机化合物的浓度在多组分气体混合物的环境，健康和安全应用的微传感器的迫切需要。新的传感器将需要实验室规模分析工具的精度和准确度，但同时必须低成本，低功耗，快速响应和便携式。目前适合便携的微传感器不能提供足够的化学选择性。传统的微传感器技术（如半导体气敏传感器），需要由上百个传感器组成的阵列才能在明确定义的气体体系中实现适度的化学特异性，提出了一种新的催化微传感器，它只需要一个固有选择性传感器就能为特定的、定义的气体分析应用提供高达100%的乙醇选择性。选择性乙醇微传感器的应用广泛且需求量大，从分析可再生液体燃料、用于污染监测的汽车和炼油应用的废气，到用于疾病检测的呼出气体。（含有有限且确定的气体混合物），通过使用纳米结构的金属氧化物催化剂来实现化学特异性，所述催化剂的表面被调整为仅选择性地氧化多组分气体混合物中所需的分析物。由放热部分氧化反应引起的温度变化将使用微量热传感器测量，以将选择性事件转化为定量浓度。这种传感方法是新颖而优雅的，其简单的原理，并可以应用于广泛的过程通过调整催化剂substrate.Specifically，过渡金属氧化物催化剂含有小的VOx，MoOx，WOx域将开发用于选择性氧化乙醇为乙醛在烃和挥发性有机化合物的混合物。使用组成、纳米结构、催化剂活性、反应机理和表面性质之间的关系，将设计具有对产物和反应物的期望特异性的混合金属氧化物催化剂。使用VOx-Al 2 O3催化剂已经表明，乙醇可以在180 ℃下优先氧化成乙醛，而多组分烃进料中存在的苯或甲烷气体与空气没有任何反应。基本发展的催化剂，动力学，和微系统设计协议所需的选择性氧化乙醇在多组分混合物将允许这种传感器的方法推广到更复杂的气体系统和application.Broader ImpactThe建议的发展选择性化学传感器使用催化传感机制和复杂的氧化催化剂将产生一个全新的研究领域。这项研究将导致两个基本的设计协议的催化传感器和实际设备的具体过程中的应用需要乙醇分析的发展。利用我们的微加工方法的特点，整合催化剂表面的测量能力，将使我们能够在新的水平上以前所未有的方式探测表面现象。通过这项工作，研究生和本科生将在催化和微系统的界面上进行研究和学习新的多学科领域的课程。妇女和少数民族高中，本科和研究生将受益于PI的持续辅导/推广工作，包括研讨会讨论令人兴奋的机会，为妇女在工程和平衡个人和职业目标的方法。

AbstractPROPOSAL NUMBER.: 0644707PRINCIPAL INVESTIGATOR: Baertsch, ChelseyINSTITUTION: Purdue UniversityThere is a critical need for microsensors capable of detecting and quantifying the concentration of hydrocarbons and volatile organic compounds in multi-component gas mixtures for environmental, health, and safety applications. New sensors will require the precision and accuracy of laboratory scale analytical tools, but at the same time must be low cost, low power, fast response, and portable. Current microsensors that are suitably portable do not provide sufficient chemical selectivity. With conventional microsensor technologies (such as semiconductor gas sensors), arrays comprised of 100s of sensors are required to achieve only modest chemical specificity in well defined gas systems.A new class of catalytic microsensor is proposed that only requires one intrinsically selective sensor to provide up to 100 % selectivity towards ethanol for specific, defined gas analysis applications. Applications for selective ethanol microsensors are broad and in demand, ranging from analysis of renewable liquid fuels, exhaust gases from automotive and refining applications for pollution monitoring, and exhaled breath for disease detection.Intellectual MeritFor a specified process application (containing a finite and determined gas mixture), chemical specificity will be accomplished by using nanostructured metal oxide catalysts with surfaces tuned to selectively oxidize only the desired analyte in multi-component gas mixtures. Temperature changes resulting from the exothermic partial oxidation reaction will be measured using microcalorimetric sensors to transduce the selective event into a quantitative concentration. This sensing approach is novel yet elegant in its simple principle and can be applied to a wide range of processes by tuning the catalyst substrate.Specifically, transition metal oxide catalysts containing small VOx, MoOx, and WOx domains will be developed for selective oxidation of ethanol to acetaldehyde in hydrocarbon and volatile organic compound mixtures. Using relationships between composition, nanostructure, catalyst activity, reaction mechanisms, and surface properties, mixed metal oxide catalysts will be designed with desired specificity towards products and reactants. It has been shown using VOx-Al2O3 catalysts that ethanol can be preferentially oxidized at 180 C to acetaldehyde without any reaction of either benzene or methane gases present in multi-component hydrocarbon feeds with air. Fundamental development of catalyst, kinetic, and microsystem design protocol required for selective oxidation of ethanol in multi-component mixtures will allow the generalization of this sensor approach to more complex gas systems and applications.Broader ImpactThe proposed development of selective chemical sensors using catalytic sensing mechanisms and complex oxidation catalysts will generate a completely new field of study. This research will lead to both fundamental design protocols for the development of catalytic sensors and actual devices for specific process applications requiring ethanol analysis. Integrating measurement capabilities at catalyst surfaces using methods characteristic of our microfabrication approaches will allow us to probe surface phenomena at new levels and in ways previously never envisioned.Through this work, graduate and undergraduate students will do research and take courses in a new multidisciplinary field at the interface of catalysis and microsystems. Women and minority high-school, undergraduate, and graduate students will benefit from the PI's ongoing mentoring/outreach efforts, including seminars discussing exciting opportunities for women in engineering and methods for balancing personal and professional goals.