Platinum loading, optimization

Optimization of electrode and MEA performance with new electrode materials (catalysts, catalyst supports, and ionomers [2]), particularly for high-current density operation with low platinum loadings. 

Another application of lanthanum as dopant for low temperature catalysts was demonstrated by Xu et. al. [105] in n-pentane isomerization, carried out at 200 °C. They had proposed an alternative catalyst based on zirconia-supported platinum and tungstophosphoric acid (TPA), whose activity was foimd to be increased with the addition of lanthanmn. Also, the optimal lanthanum amoimt strongly depended on the platinum loadings. 

However, the PEMFC stack has the greatest potential for cost reduction. Cell power density would have the greatest effort for the optimization. For stationary applications, lower current densities could be acceptable than used in transport applications in order to increase efficiency. A balance has to be made between system efficiency and acceptable stack current density, effectively stack cost/kW output. Another opportunity to reduce the costs lie in identifying a cheaper membrane, electrode material as well as lower platinum loadings in the electrodes. 

The experimental optimization of Nafion ionomer loading within a catalyst layer has attracted widespread attention in the fuel cell community, mainly due to its critical role in dictating the reaction sites and mass transport of reactants and products [15,128-134]. Nafion ionomer is a key component in the CL, helping to increase the three-phase reaction sites and platinum utilization to retain moisture, as well as to prevent membrane dehydration, especially at low current densities. Optimal Nafion content in the electrode is necessary to achieve high performance. 

Reductive alkylation is an efficient method to synthesize secondary amines from primary amines. The aim of this study is to optimize sulfur-promoted platinum catalysts for the reductive alkylation of p-aminodiphenylamine (ADPA) with methyl isobutyl ketone (MIBK) to improve the productivity of N-(l,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (6-PPD). In this study, we focus on Pt loading, the amount of sulfur, and the pH as the variables. The reaction was conducted in the liquid phase under kinetically limited conditions in a continuously stirred tank reactor at a constant hydrogen pressure. Use of the two-factorial design minimized the number of experiments needed to arrive at the optimal solution. The activity and selectivity of the reaction was followed using the hydrogen-uptake and chromatographic analysis of products. The most optimal catalyst was identified to be l%Pt-0.1%S/C prepared at a pH of 6. 

The application of transition metal oxide monolayer/support systems as carriers for platinum allows the possibility of modification of the properties of platinum in a wide range [5]. According to our previous works we adopted an optimal loading of platinum (2 %w). The reaction of platinum compound with OH groups of the support proceeded to the formation of transition metal-O-Pt bond, according to the reaction (3) - a useful tool for obtaining well dispersed noble metal on the surface of inorganic support [6,7]. 

The hydrogen oxidation is a much faster reaction, and is usually not limiting the fuel cell performance. Platinum is the optimal catalyst, but nevertheless, loadings of... 

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