Platinum impregnation

Fig. 11. EPR spectra of Ti3+ (at 77 K) showing the influence of Cs exchange and platinum impregnation on the intensity and g-parameters of Ti3+ signals in ETS-10 reduced in dry H2 at 673 K (signals denoted by an asterisk correspond to superoxide radical species generated by secondary reactions by Ti3+ interaction with 02) [from Bal et al. (130)].

Fig. 2. Isomerization of n-heptane over mixtures of particles of silica-alumina and particles of inert-supported platinum (W5). The dashed lines represent conversions over platinum-impregnated silica-alumina. Conditions of runs 25 atm., Hj/nC = 4/1, space velocity = 0.7 g. nC7 per hour per gram of catalyst.

Spieker WA, Regalbuto JR. A fundamental model of platinum impregnation onto alumina. Chem Eng Sci. 2001 56 3491-504. 

Commercial zeolite based hydroisomerization catalysts comprise alumina bound and platinum impregnated dealuminated mordenite. The activity and selectivity of the hydroisomerization of n-paraffins is strongly influenced by acid leaching. The influence of silica to alumina ratio has been studied for pentane isomerization over platinum mordenite many times since one of the first papers published (6). 

Dorado E, de Lucas-Consuegra A, Vemoux P, Valverde JL (2007) Electrochemical promotion of platinum impregnated catalyst for the selective catalytic reduction of NO by propene in presence of oxygen. Appl Catal B Environ 73 42-50... 

Carbon supports typically undergo chemical or physical activation prior to platinum impregnation. The alteration of surface groups and functionalities on the carbon support can strongly influence the carbon-metal interaction that can directly affect the metal particle size, metal particle distribution, surface morphology of the carbon, and surface impurities that may be present. These parameters have been known to influence the catalytic metal stability and activity of the resulting catalyst. Common surface modifications strategies include chemical oxidation of the carhon or thermal activation to modify the surface structures. 

HO radicals is similar for a membrane in H O, as well as for alone. Fe -doped PFSA membranes show more than 1 order of magnitude increase of the HO radicals, while platinum-impregnated membranes show fewer radicals. 

In 1959, William Grubbs used organic cation exchange polymers in fuel cells. As shown in Fig. 1.9, the cell consists of polymer electrolyte sandwiched between platinum impregnated porous electrodes. Teflon is coated on the electrodes to make them hydrophobic. The operation temperature of PEFMC can be within 80-200°C. The low operation temperature of PEMFC offers quick start-up but platinum catalysts are required to promote the electrochemical reaction. Platinum particles are deposited very finely onto carbon powders to attain the maximum surface area. The contact between gas, electrolyte and platinum catalyst should be good for the uninterrupted function of PEFMC. 

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