Removal of carbon monoxide from hydrogen gas using platinum and palladium catalyst in electrochemical water gas shift reaction

Abstract

Proton exchange membrane fuel cell (PEM-FC) uses hydrogen as the feed gas and converts it directly into electrical energy. However, the high performance of PEM fuel cell is degraded as the accumulated carbon monoxide (CO) conquers the active sites of the anode catalyst which solely belongs to hydrogen molecules. This research focused on the application of PEM fuel cell as an electrochemical (CO) converter. The reversible concept of fuel cell was utilized to convert the CO to carbon dioxide (CO2) as to obtain a tolerance concentration of CO. The electrochemical CO converter underwent the electrochemical water gas shift reaction (EWGSR) in order to convert the CO to CO2. Five membrane electrode assemblies (MEA) samples with different ratios of platinum (Pt) to palladium (Pd) on activated carbon (Ac) and coated on polybenzimidazole (PBI) membrane were prepared. The Pt-Pd/Ac MEA samples were in the range of 1:0 to 1:4 which represent Pt:Pd ratios. The samples were tested by using hydrogen-rich gas (CO/H2) with 100 ppm of CO. The PBI membrane was used for electrochemical CO converter as it is cheaper and can tolerate the CO without controlling the humidity content. The process parameters were CO/H2 flow rate, voltage of power supply and operating temperature of electrochemical CO converter. The performance of the sample was found to increase at three operating conditions which is the CO/H2 gas flow rate is 50 ml/min with 0.7V voltage at room temperature. The result was 96.73% of CO conversion.