Aqueous-Alkaline/Carbonate Biocarbon Fuel Cell Development

该项目的目标是开发一种水碱性/碳酸盐生物碳燃料电池，该电池通过利用在接近300°C的温度下有利的电化学反应，在实现电解质不变性的同时表现良好。更广泛的影响。大量的木质纤维素残留物（如玉米芯、椰子壳）伴随着生物乙醇和生物柴油燃料的生产。这些残留物可以高效、快速地转化为生物碳。碳燃料电池可以从这些生物碳中发电，也可以从煤和其他化石碳中发电，理论上的热力学效率为100%。EPRI最近的一项研究表明，碳燃料电池有潜力将生物碳转化为电能，系统级效率约为60%，比目前最先进的综合气化联合循环（IGCC）或先进的煤粉发电系统的效率高出20%以上。因此，生物碳的生产可以补充生物乙醇和生物柴油在生物质精炼厂的生产，也以非常高的效率发电。其他影响包括培训两名学士和两名硕士学生，夏威夷太平洋大学（HPU）教师的参与，以及在UH和HPU课程中开发和包含新的电化学工程课程材料。鉴于夏威夷州不提供化学工程专业的大学学位，这些影响具有特殊的意义。知识价值。这个项目基于两个假设。1)在接近300°C的温度下，水碱性/碳酸盐生物碳燃料电池将提供约1 V的开路电压（OCV）和超过100 mW/cm2的稳定最大功率密度。2)在运行过程中，电解质的组成将演变为氢氧化物和碳酸盐离子的平衡混合物，之后将保持不变（即稳定）。这种电池的阴极类似于培根燃料电池的阴极，空气中的氧在银催化剂上被还原成氢氧离子。热力学分析表明，阴极在接近300°C的温度下表现良好。同样，热力学分析表明，在这些温度下，氢氧化物离子和碳酸盐离子（由二氧化碳与氢氧化物离子反应形成）都应强烈氧化碳阳极并释放电子；从而高效率地发电。该项目有三个目标：1)表征燃料电池在水-碱/碳酸盐环境下阳极炭-煤在温度接近300°C时的氧化行为；2)表征电解质的稳定性，以及在300℃附近不同电解质对阳极和阴极反应的催化作用；3)表征生物碳阳极作为工作电极的性能，该工作电极包括一个反电极，电解质通过热交换器桥流到参考电极，保持在系统压力下，但温度要低得多。

CBET-0828006AntalThe aim of this project is the development of an aqueous-alkaline/carbonate biocarbon fuel cell which performs well while realizing electrolyte invariance by exploiting electrochemical reactions that are favored at temperatures near 300 °C. Broader impacts. Very large quantities of lignocellulosic residues (e.g. corncobs, coconut shells) accompany the production of bioethanol and biodiesel fuels. These residues can be efficiently and quickly converted into biocarbons. Carbon fuel cells can generate electricity from these biocarbons -as well as from coal, and other fossil carbons-with a theoretical thermodynamic efficiency of 100%. A recent EPRI study indicates that carbon fuel cells have the potential to convert biocarbons into electrical power at a system level efficiency of about 60%, which is over 20% higher than the efficiencies realized by current state-of-the-art integrated gasification combined cycle (IGCC) or advanced pulverized coal power generation systems. Thus the production of biocarbon can complement the production of bioethanol and biodiesel in a biomass refinery that also produces electricity at a very high efficiency. Other impacts include the training of two BS and two MS students, the involvement of Hawaii Pacific University (HPU) faculty, and the development and inclusion of new electrochemical engineering course material in the UH and HPU curricula. In view of the fact that a college degree in chemical engineering is not offered in the State of Hawaii, these impacts have special significance. Intellectual merit. This project is based on two hypotheses. 1) At temperatures approaching 300 °C the aqueous-alkaline/carbonate biocarbon fuel cell will offer an open circuit voltage (OCV) of about 1 V and a steady, maximum power density that exceeds 100 mW/cm2. 2) During operation the composition of the electrolyte will evolve towards an equilibrium mixture of hydroxide and carbonate ions that afterwards will be invariant (i.e. stable). The cathode of this cell resembles that of a Bacon fuel cell, where oxygen in air is reduced to hydroxide ion over a silver catalyst. Thermodynamic analyses indicate that the cathode should perform well at temperatures approaching 300 °C. Likewise, thermodynamic analyses indicate that at these temperatures both the hydroxide ion and the carbonate ion (formed by the reaction of CO2 with hydroxide ion) should vigorously oxidize the carbon anode and release electrons; thereby generating power at high efficiency. This project has three objectives: 1) to characterize the oxidation behavior of anodic char-coal in the aqueous-alkaline/carbonate environment of the fuel cell at temperatures near 300 °C; 2) to characterize the stability of the electrolyte, together with the catalytic effects of differing electrolytes on the anodic and cathodic reactions at temperatures near 300 °C; and 3) to characterize the performance of the biocarbon anode as a working electrode in a setup that includes a counter electrode, and flow of the electrolyte through a heat exchanger bridge to a reference electrode maintained at system pressure but at a much lower temperature.