Kong Eugene H, Maimani Fares, Prakash G K Surya, Ronney P D
Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089, USA.
Loker Hydrocarbon Institute, University of Southern California, Los Angeles, CA, 90089, USA.
Sci Rep. 2024 Aug 1;14(1):17865. doi: 10.1038/s41598-024-68832-7.
Hydrocarbon fuels contain approximately 50 times more energy per unit mass than commercial batteries, thus converting even 10% of the energy contained in hydrocarbon fuels to electrical energy could present a more mass-efficient electrical energy source than batteries. Considering the storability of hydrocarbon fuels compared to hydrogen, the viability of direct hydrocarbon polymer electrolyte membrane fuel cells was examined. With extremely pure (> 99.99%) propane, the cell Open-Circuit Voltage (OCV) was only 0.05 V and produced negligible power. However, with addition of trace quantities of unsaturated hydrocarbons, the cell had an OCV of 0.85 V and produced power, even after the unsaturated hydrocarbon addition was discontinued. At sufficiently high current densities, power output gradually decreased then the cell rapidly "extinguished" but by periodically shutting off the current for short time intervals the average power density could be increased significantly. Chemical analysis revealed that no significant amounts of hydrocarbon intermediates or CO were present in the effluent and that conversion of the hydrocarbon fuel to CO and HO was nearly complete. An analytical model incorporating the relative rates of conversion of active anode catalyst sites to inactive sites and vice versa was developed to interpret this behavior. The model predictions were consistent with the experimental observations; possible physical mechanisms are discussed.
碳氢燃料每单位质量所含的能量约为商用电池的50倍，因此，即使将碳氢燃料所含能量的10%转化为电能，也可能成为一种比电池质量效率更高的电能源。考虑到碳氢燃料与氢相比的可储存性，研究了直接碳氢聚合物电解质膜燃料电池的可行性。使用极纯（>99.99%）的丙烷时，电池开路电压（OCV）仅为0.05 V，产生的功率可忽略不计。然而，添加微量不饱和烃后，电池的开路电压为0.85 V并产生功率，即使在停止添加不饱和烃后依然如此。在足够高的电流密度下，功率输出逐渐下降，然后电池迅速“熄灭”，但通过定期短时间切断电流，平均功率密度可显著提高。化学分析表明，流出物中不存在大量的碳氢化合物中间体或CO，碳氢燃料向CO和H₂O的转化几乎是完全的。建立了一个分析模型，该模型纳入了活性阳极催化剂位点与非活性位点相互转化的相对速率，以解释这种行为。模型预测结果与实验观察结果一致；并讨论了可能的物理机制。
