CAREER: Electrochemical pumping with high-temperature ionomers for challenging gas separations

氢是一种重要的能源载体和化学原料，预计将被广泛采用，因为它能够使美国经济中困难的部门脱碳，例如化肥生产、金属精炼/钢铁生产和重型车辆运输的动力。此外，对于间歇性可再生发电和需要长期季节性储能时，氢是一种具有成本效益的储能解决方案。要实现减少温室气体和碳排放的宏伟目标，就必须成熟产生、储存和分配氢的电化学技术。该项目旨在了解电化学氢泵（EHPs）中的电极聚合物粘结剂材料如何影响从含有低氢浓度（1%至20%）的挑战性气体混合物中净化氢的效率。这一点很重要，因为有人认为，美国现有的天然气管道可能有能力储存和分配来自集中生产设施的氢气。利用现有的基础设施可以降低最终用户的氢气成本，因为氢气的储存和分配占了今天氢气成本的很大一部分。然而，终端应用需要高压下的纯氢。因此，EHPs是一种很有前途的技术，可以将氢气从气体混合物中分离出来，同时对其进行压缩。提高电化学氢泵材料的性能和耐用性，如电极粘合剂，可以降低EHPs的资本成本，同时提高其能源效率。电化学过程将使化学过程脱碳，对培养精通电化学工程和电化学系统集成的未来工程师至关重要。该项目将在宾夕法尼亚州立大学的单元操作实验室委托第一个电化学单元操作，即EHP，为学生提供电化学系统的实践培训。该项目的推广活动将吸引和招募来自宾夕法尼亚州中部农村社区的个人，向他们传授使用电化学系统进行可持续化学生产的知识。本基础研究项目的总体目标是了解电极离聚体粘结剂的组成和加工如何影响高温聚合物电解质膜（HT-PEM）电化学氢泵（EHPs）中氢的扩散率和氢的氧化/析出反应动力学。随着离子对HT-PEMs和磷酸离聚体电极粘合剂的出现，初步实验证明氢从合成气和其他具有不同氢和一氧化碳浓度的重整碳氢化合物中分离出来，在1 A cm-2下达到+99.3%的氢。在这些实验中，我们观察到细胞极化很大程度上是由混合气体饲料中的氢含量决定的，因为CO中毒被最小化了。用含氢量低的气体进料解决EHP电池极化问题需要新的电极粘合剂，以促进氢的扩散，并促进更好的电催化剂利用。该项目将建立结构-性质关系，将离聚体组成和加工与反应动力学-输运性质联系起来。这些离聚体的电化学性能将在嵌段共聚物模板所提供的纳米级电催化剂修饰的交错电极阵列上作为薄膜进行探测。用含有新离子的膜电极组件进行EHP研究将用于了解从低氢含量气体混合物中纯化氢的细胞极化行为。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Hydrogen is an important energy vector and chemical feedstock and is expected to see wide-spread adoption because of its ability to decarbonize difficult sectors of the U.S. economy – e.g., fertilizer production, metal refining/steel production, and powering heavy duty vehicle transportation. Furthermore, hydrogen is a cost-effective energy storage solution for intermittent renewable electricity generation and when long-term seasonal energy storage is required. Meeting ambitious goals of greenhouse gas and carbon emission reduction necessitates the maturation of electrochemical technologies that generate, store, and distribute hydrogen. This project seeks to understand how electrode polymeric binder materials in electrochemical hydrogen pumps (EHPs) affect the efficiency performance for hydrogen purification from challenging gas mixtures that contain low hydrogen concentrations (1% to 20%). This is important because it is posited that U.S.’s existing natural gas pipelines may have the ability to store and distribute hydrogen from centralized production facilities. Leveraging existing infrastructure can reduce the cost of hydrogen to end users as hydrogen storage and distribution make up a large portion of the cost of hydrogen today. However, endpoint use applications necessitate pure hydrogen at high pressures. Hence, EHPs are promising technology to separate hydrogen from gas mixtures while simultaneously compressing it. Advancing materials’ performance and durability for electrochemical hydrogen pumps, such as electrode binders, can reduce capital costs for EHPs while also improving their energy efficiency. Electrochemical processes are poised to decarbonize chemical processes and is paramount to train future engineers proficient in electrochemical engineering and electrochemical systems integration. This project will commission the first electrochemical unit operation, an EHP, in Penn State’s Unit Operations Laboratory to give students hands-on training with electrochemical systems. Outreach activities for this project will engage and recruit individuals from rural communities in central Pennsylvania to teach them about sustainable chemical manufacturing using electrochemical systems.The overall goal of this fundamental research project aims to understand how electrode ionomer binders’ composition and processing influence hydrogen diffusivity and hydrogen oxidation/evolution reaction kinetics in high-temperature polymer electrolyte membrane (HT-PEM) electrochemical hydrogen pumps (EHPs). With the advent of ion-pair HT-PEMs and phosphonic acid ionomer electrode binders, preliminary experiments demonstrated hydrogen separations from syngas, and other reformed hydrocarbons with varying hydrogen and carbon monoxide concentrations, to +99.3% hydrogen at 1 A cm-2. In these experiments, it was observed that cell polarization was largely governed by hydrogen content in the gas mixture feed because CO poisoning was minimized. Addressing EHP cell polarization with gas feeds containing low hydrogen content requires new electrode binders that promote hydrogen diffusivity and foster better electrocatalyst utilization. This project will establish structure-property relationships that correlate ionomer composition and processing to reaction kinetics-transport properties. These ionomer electrochemical properties will be probed as thin films on interdigitated electrode arrays decorated with nanoscale electrocatalysts afforded from block copolymer templating. EHP studies with membrane electrode assemblies containing the new ionomers will be used for understanding cell polarization behavior for purifying hydrogen from gas mixtures with low hydrogen content.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.