No abstract

The performance of 1 kWel 48-cell HT-PEMFC at various experimental conditions is presented, particularly at several CO concentrations (up to 1.0%). Polarization curves measured at various anode (1.0-2.5) and cathode (1.6-4.0) stoichiometries; stack operating temperatures (120-160 o C) and gas pressures (up to 0.5 barg) are reported and analysed. The minimum gas stoichiometries of 1.25 and 2.0 were determined for the anode and cathode, respectively. The highest stack power density of 225 mW cm-2 was measured at 160 o C and 0.4 A cm-2. Operation at CO concentrations up to 1% was achieved, although a loss of performance of about 4% was observed for low CO concentrations. The operating temperature enhanced fuel cell performance and tolerance to CO, even when supplied with higher CO concentration in the anode feed gas.

No abstract

Bifunctional solid catalysts facilitate the esterification of free fatty acids (FFA) into alkyl esters alongside the transesterification reaction, which allows for the use of waste vegetable oils with high water and FFA contents for biodiesel production. This makes the process economically viable and greener, as the waste fats and oils are readily available. The concurrent esterification and transesterification of waste palm oil (WPO) and waste sunflower oil (WSO) with methanol was investigated in the presence of calcium oxide on alumina catalyst in a conventional batch process. The catalyst characterization showed the existence of calcium oxide aluminates (calcined at 750 °C), which exhibited crystalline phases with porous/spongy-like particles. The high concentration of CaO in CaO/Al2O3 was a favorable support material in the heterogeneously-catalyzed transesterification reactions. The optimum catalyst parameters for the production of fatty acid methyl esters (FAMEs) were observed at 65 °C for 4 h with a methanol-to-oil ratio of 9:1, 60% (waste palm oil, or WPO) and 80% (waste sunflower oil, or WSO), CaO/Al2O3 (% wt/wt) catalyst ratio as well as 4% CaO/Al2O3 concentration (% wt.) for WSO and WPO. The simultaneous esterification/transesterification reactions at optimum conditions on WPO and WSO led to high yield of FAMEs of 89, 61 and 55% for WPO and 54, 75 and 98% for WSO at catalyst ratios (wt %) of 60, 70 and 80% respectively. The use of bifunctional heterogeneous catalyst (CaO/Al2O3) with waste vegetable oil can result in high performance and the upscaling of biodiesel production.

No abstract