秸秆水热炭与碳微球制备复合质子交换膜方法研究

Preparation and Performance Investigation of Cycled Hydrothermal Carbon and Carbon Microspheres from Straw and Their Composite Proton Exchange Membranes

摘要:

为实现秸秆水热液高值化利用并提升SPEEK基质子交换膜的综合性能,本研究以玉米秸秆为原料,通过液体循环和提质分别制备水热炭(HC)与碳微球(MC),并将其引入SPEEK基体中制备复合质子交换膜,系统考察填料形貌结构、膜稳定性、吸水溶胀行为、质子传导率、甲醇渗透率、选择性及单电池性能。结果表明,复合质子交换膜整体综合性能总体优于纯SPEEK膜。Fenton试剂处理后质量损失率降至4.80%~12.68%,抗氧化性能明显改善;接触角降至66.3°~69.2°,亲水性显著改善。在6种复合质子交换膜中,柠檬酸介质碳微球复合质子交换膜(SPEEK/MC-CA)综合性能最优:80℃下吸水率为64.03% ,接触角为66.3°;在80℃、相对湿度100%条件下质子传导率0.159S/cm,较纯膜提升109% ;甲醇渗透率达到4.51×10??cm2/s,选择性指数为2.69×10?S·s/cm3;单电池开路电压为0.77V,峰值功率密度达到106.01mW/cm2,较纯SPEEK膜和Nafion-115膜分别提高59.05%与24.70%。柠檬酸介质液体产物衍生碳微球能够协同提升SPEEK膜的质子传导、甲醇阻隔和甲醇燃料电池的输出性能。

Abstract:

Aiming to address the trade-off between proton conductivity and methanol barrier performance in sulfonated poly ( ether ether ketone) ( SPEEK) proton exchange membranes while achieving highvalue utilization of straw hydrothermal liquid, hydrochar (HC) and carbon microspheres (MC) were prepared from corn straw via liquid product recycling and upgrading, respectively, and incorporated into an SPEEK matrix at a doping content of 3% to fabricate composite proton exchange membranes via solution casting. The effects of the fillers on membrane morphology, thermal and oxidative stability, water uptake and swelling behavior, proton conductivity, methanol permeability, selectivity, and single-cell performance were systematically investigated. The results demonstrated that the composite membranes exhibited significantly superior comprehensive performance compared with the pristine SPEEK membrane. The mass loss rate after Fenton reagent treatment was decreased to 4.80% ~ 12.68%, indicating markedly improved oxidative stability; and the water contact angle was decreased to 66.3°~ 69.2, hydrophilicity was significantly improved. Among the six composite membranes, the citric acid-derived carbon microsphere composite membrane (SPEEK/MC-CA) exhibited the best comprehensive performance: the water uptake was 64.03% and the water contact angle was 66.3° at 80℃; the proton conductivity reached 0.159S/cm at 80℃ under 100% relative humidity, which was 109% higher than that of the pristine SPEEK membrane; the methanol permeability was 4.51×10??cm2/s and the selectivity index was 2. 69×10?S·s/cm3; the open circuit voltage of the single cell was 0.77V and the peak power density reached 106.01mW/cm2, which were 59.05% and 24.70% higher than those of the pristine SPEEK membrane and Nafion-115, respectively. The carbon microspheres derived from citric acid-assisted hydrothermal liquid synergistically enhanced the proton conductivity, methanol barrier performance, and power output of SPEEK-based direct methanol fuel cells.