Real-Time Mass Spectrometric Analysis of the Anode Exhaust Gases of a Direct Propane Fuel Cell

Abstract

The exhaust gases composition of a direct propane fuel cell ͑DPFC͒ operating at 80°C was studied by mass spectrometric methods. Blank propane was introduced in the anode chamber without external reforming. The effect of the anode catalysts on the composition of the exhaust gases was investigated. It was found that the mass spectra of the electro-oxidized propane presented significant differences compared to the mass spectra of the blank propane introduced directly into the mass spectrometer. It was found that the operation of the DPFC at 80°C involves several processes, i.e., adsorption, dehydrogenation, and C-C bond cleavage of the molecule. It was shown that the intensity of the peaks associated with species like CH 4 , CO, and C 2 H 4 increases with the polarization potential of the fuel cell. The opposite effect was found for the relative intensity of the molecular ion at m/z = 44, which decreased with the cell polarization potential. These spectrometric characteristics indicate that the composition of the anode exhaust gases is related to the polarization conditions. These results confirm that the direct propane electro-oxidation was responsible for the operation of the DPFC.We have reported the characteristics of a direct propane fuel cell ͑DPFC͒ operating at 80°C in previous works. 1-4 We have described the experimental setup and procedure, as well as the electrochemical behavior of several Pt-based anode electrocatalysts for the direct electro-oxidation of propane in DPFC. 1-4 Some of the anode materials tested in the DPFC are Pt-metal oxides which have shown a high catalytic activity for the electro-oxidation of propane. 1-4 Some of the investigations related to the development of direct propane fuel cells in our laboratory includes the use of mass spectrometry ͑MS͒ to analyze the composition of the outlet gases of the cell produced during the electrochemical oxidation of the propane in the fuel cell. This type of spectrometric experiments allows the detection of volatile products and intermediates which are produced during the electrochemical reaction of organic substances used to feed polymer electrolyte fuel cells ͑PEFC͒. 5 Thus, it is possible to determine the reaction mechanisms of a variety of substances under fuel cell operating conditions. In the case of carbonaceous organic molecules, the main interest in fuel cell applications is to achieve a complete oxidation of the substance to CO 2 with maximum conversion efficiencies.Integrated MS-electrochemical techniques have been used to analyze the electrochemical behavior of adsorbed species formed in fuel cell gas diffusion anodes in the presence of methanol, 5,6 trimethoxymethane, 7 and formic acid. 8 Using the method of differential electrochemical mass spectrometry ͑DEMS͒, it was possible to detect CO 2 as some reaction products of the catalytic oxidation of small organic molecules on Pt-based electrocatalysts. 9,10 DEMS techniques have also been used to investigate the oxidation processes of carbon monoxide, 11 methanol, 12,13 ethanol, 14,15 and...

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Energy Generation from Pharmaceutical Residual Water in Microbial Fuel Cells Using Ordered Mesoporous Carbon and Bacillus subtilis as Bioanode

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