Pt-loading

Polymer Electrolyte Fuel Cell. The electrolyte in a PEFC is an ion-exchange (qv) membrane, a fluorinated sulfonic acid polymer, which is a proton conductor (see Membrane technology). The only Hquid present in this fuel cell is the product water thus corrosion problems are minimal. Water management in the membrane is critical for efficient performance. The fuel cell must operate under conditions where the by-product water does not evaporate faster than it is produced because the membrane must be hydrated to maintain acceptable proton conductivity. Because of the limitation on the operating temperature, usually less than 120°C, H2-rich gas having Htde or no (

Very substantial advances have been made in terms of improvements in electrode stmctures and increases in the Pt utili2ation as illustrated in Figure 1. It appears that Pt loadings of less than 0.2 mg Pt/cm are adequate to obtain acceptable performance in PEFCs using pure H2 as the fuel (see Thin films). Whereas early electrodes contained 4 mg Pt/cm, the most recent developments in electrode fabrication have permitted Pt loadings to be reduced to 0.13 mg Pt/cm in a thin-film stmcture, while maintaining high performance. 

The primary target of studies on photocatalytic semiconductor suspensions has been water cleavage by visible light. Suspension-based photocatalytic processes are also useful for the removal of inorganic (metal ions) and organic pollutants, the reduction of CO2, the photodestruction of bacteria and viruses, and various organic reactions an example is the use of Pt-loaded CdS for the photocatalytic racemization of L-lysine [210]. 

V with air were attained. The group at the University of Newcastle also reported similar performances using electrodes with a Pt loading of about 2 mg/cml ... 

Figure 17. Voltage and power density as a function of current density for a DMFC single cell. Overall Pt loading of 2.6 mg/cm, anode feed of 1 Mmethanol, cathode feed of 30 psig air. (After Ref 106 reproduced with permission.)...

We measured the dispersion of Pt (impregnated from a chloroplatinic acid precursor, calcined at 450 C and reduced at 500 C) on a series of Nd203-loaded silica-aluminas (Fig. 8). We find, unexpectedly, that dispersion increases with increasing rare earth oxide loading up to about 18% Nd203, where it plateaus at between 40 and 50%, compared to 10% with unmodified Si-Al. This compares with dispersions of -60-80% measured on similarly Pt-loaded transitional AI2O3 catalysts. Transmission electron micrographs confirmed the decrease in particle size with rare earth content on Si-Al. 

GP 1] [R 1] A comparison of four micro reactors (see Table 3.1) with different Pt loadings (Pt impregnated on an anodically oxidized alumina support) confirmed that higher conversions were obtained at higher Pt loadings (6 vol.-% NH3, 88 vol.-% O2, balance He 600-4430 cm min (STP) 260-380 °C) [28,98]. At near complete conversion, 48% N2O selectivity was found (Figure 3.27). 

Wilson MS, Gottesfeld S. 1992. High performance catalyzed membranes of ultra-low Pt loadings for polymer electrolyte fuel cells. J Electrochem Soc 139 L28-L30. 

Brankovic SR, Wang JX, Adzic RR. 2001b. Pt submonolayers on Ru nanoparticles—A novel low Pt loading, high CO tolerance fuel cell electrocatalyst. Electrochem Solid State Lett 4 A217-A220. 

Figure 10.10 Temperature dependence of H2O2 yield F(H202) at Nafion-Pt(4.8 nm)/CB (O), Nafion—Pt(2.6nm)/CB (A), Nafion—Pt(1.6 nm)/CB (O ), Nafion-Pt(2.6nm)/CB with the same Pt loading as 1.6 nm catalyst ( ), Nafion-Pt(bulk) ( ), and Pt(bulk) without Nafion coating (v)- t m = 50cms (From Yano et al. [2006b], reproduced by permission of the PCCP Owner Societies.)...

Figure 11.1 Kinetics of adsorption of CO at a Pt catalyst from a 0.01 M methanol solution at different potentials, (a) Pt black catalyst, with Pt loading 0.8 mg cm . (b) Pto.sRuo.s black catalyst, with catalyst loading 0.8 mg cm (0.1 M H2SO4, T = 298K).

It is known that the addition of Pt errhances the activity of hyam catalysts while sacrificing selectivity [4-5]. Bimetallic catalysts were prepared and tested to see if one could improve the activity of these catalysts while maintaining the good selectivity. As expected, Catalyst A with an 8% Pd + 2% Pt loading showed an increased activity of 57.3 compared to 32.7 for Catalyst A with a 10% Pd loading (Table 10.2). On the other hand, the selectivity of the bimetallic catalyst was... 

ELAT Solid Polymer Electrolyte Electrode 20% Pt/C with 0.4 mg/cm2 Pt loading E-Tek, Inc., 1 Mountain Rd, Framingham Industrial Park, Framingham, MA 01701 508-879-0733... 

Level Cycle time (s) Lean fraction Pt loading (%) Ba loading (%) Fe loading (%)... 

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