The influence of impurities in high temperature polymer electrolyte membrane fuel cells performance

Abstract

This work investigates the influence of carbon dioxide and non-reacted methanol, present in the reformate stream obtained via methanol steam reforming, in the performance of high temperature polymer electrolyte membrane fuel cells (HT-PEMFC), operating between 160 °C and 180 °C.The HT-PEMFC anode was fed with pure hydrogen, hydrogen balanced with carbon dioxide (75 % / 25 % vol.) and synthetic reformate mixture, considering also vaporized methanol solution in the reformate content (up to 10 % vol.). The synthetic reformate was feed during cycles of 420 min. The fuel cell was characterized based on the polarization curve and electrochemical impedance spectroscopy (EIS) analysis. Additionally, acid-base titrations were performed to access the phosphoric acid content in different sections of the MEAs as well as scanning electron microscopy (SEM).A low impact in the fuel cell performance was observed when three cycles of synthetic reformate containing methanol solution were performed. When the number of cycles was increased, the performance of HT-PEMFC decreases and irreversible degradation of performance was observed. The cycles with synthetic reformate increased the ohmic resistance and high frequency resistance associated with anodic processes, but decreased the intermediate frequency resistance associated with cathodic processes. Additionally, by increasing the number of cycles, the phosphoric acid content of Celtec ® MEAs and the thickness of the membrane decreased. Keywords:Polymer electrolyte membrane fuel cell Polybenzimidazole Reformate gas Methanol Impurities effectElectrochemical impedance spectroscopy

Durability and degradation of vapor-fed direct dimethyl ether high temperature polymer electrolyte membrane fuel cells

“…While degradation rates as low as 0.5 μV h -1 have been achieved for PBI/phosphoric acidbased cells at 160 °C and 200 mA cm 2 with hydrogen and air over 9200 h [23], cells fed directly with methanol/water vapor mixtures [12,13,15] or reformates with high methanol residual contents [18] degrade at a much faster rate. This is, at least partly, due to the severe chemical incompatibility between the methanol fed to the anode and the phosphoric acid within the polymer membrane and electrode structures, resulting in formation of methyl phosphates with lower proton conductivity and higher volatility than phosphoric acid [24].…”

“…Furthermore, the one-phase gaseous system at temperatures well above 100 °C reduces the adverse effects of electrode flooding, which is a major shortcoming of liquid-fed direct methanol fuel cells [11]. These have been very convincing arguments for this technology and triggered substantial research in the field of direct methanol [12,13] or reformate [14][15][16][17][18][19][20][21][22] fed HT-…”

Development of effective bimetallic catalyst for high‐temperature PEM fuel cell to improve CO tolerance

“…47 The water was constituted due to this reaction, which may hinder the pores of the supported catalyst, and caused loss of performance. 67 As seen from Figure 9, the highest fuel cell performance was observed for PtPd/MWCNT-GNP catalyst. According to the results, the PtPd/MWCNT-GNP catalyst displayed the power density at 0.6 V was 0.140 W/cm 2 and the current density at 0.6 V was 0.240 A/cm 2 in the reformate gas/air environment.…”

“…The moisture‐free supply of the anode gas stream exchanges the balance of CO formation with RWGS (H 2 + CO 2 → H 2 O + CO) 47 . The water was constituted due to this reaction, which may hinder the pores of the supported catalyst, and caused loss of performance 67 . As seen from Figure 9, the highest fuel cell performance was observed for PtPd/MWCNT‐GNP catalyst.…”

Окислительная Паровая Конверсия Метанола В Микроканальном Реакторе

“…Для ТЭ с протонобменными мембранами на основе Нафиона (PEMFC) этот уровень не должен превышать 20 ppm, поэтому в дополнение к реактору ПКМ на выходе из него устанавливают реакторы паровой конверсии CO и селективного окисления («дожигания») CO [6]. В последнее время появились публикации о разработке ТЭ на основе мембран из полибензимидазола, допированных фосфорной кислотой (PAFC), которые могут стабиль-но работать при концентрации CO 1-3 % [7]. На рисунке 4 приведены зависимости концентрации CO на выходе из реактора ОПКМ от объёмной скорости кислорода на входе.…”