Platinum Pt catalyst

Alcohols can be obtained by reacting of aldehydes, ketones or carboxylic acids with hydrogen gas in the presence of a platinum (Pt) catalyst. As a result of the reduction of aldehydes by one degree and carboxylic acids by two degrees primary alcohols are obtained. Reduction of ketones by one degree produces secondary alcohols. 

ORR on platinum (Pt) catalyst is the most important system that has been given the most extensive study in the literature. Here we take this system as an example to show how to obtain electrode kinetic information of ORR. 

Fuel Flexibility Because the operating temperature is high, electrode reactions take place in fast speed. Nickel (Ni) is used for both electrodes instead of expensive platinum (Pt) catalyst It means no carbon monoxide (CO) poisoning of Pt. Ni acts as a catalyst and CO in the fuel gas (if there is any) supplies H2 by the shift reaction (CO + H2O = H2 + CO2) relating to the reaction of (1). Therefore, it becomes possible to use the gasification gas of coal, biomass, and waste which contain certain percentage of CO. 

Methyl phenyl ketone (acetophenone, C6H5COCH3) can be reduced to 1-phenylethanol [C6HsCH(OH)CH3], Equation 9.14, under the same conditions (in ethanol, CH3CH2OH, solvent) in 2.5 h. However, with a platinum (Pt) catalyst in ethanoic acid (acetic acid, CH3CO2H), the reduction of methyl phenyl ketone (acetophenone, C6H5COCH3) is very fast and most of the product is phenylethane, hydrogenolysis having occured (Equation 9.15). 

It will be recalled that methane (CH4) can be converted to nitromethane (H3CNO2) by the action of nitric acid on methane at high temperature (Chapter 6, Equation 6.10). The nitration of other alkanes by the same process can also be effected, but separation of the multitude of isomers that can be formed (from all but the simplest alkanes) can be difficult. Nitroalkanes, R-NO2 (sometimes accompanied by their corresponding nitrite isomers, R-ONO), can also be prepared (as shown in Chapter 7, Table 7.5e) by treatment of alkyl halides with nitrite anion (ONO ). Reduction of nitroalkanes (R-NO2) with hydrogen (H2) in the presence of a platinum (Pt) catalyst or lithium aluminum hydride (LiAIlT,) in ether produces the corresponding amine (Equation 10.18). 

Hydrogenolysis (reduction with bond breaking) of benzylamines resulting in the formation of toluene and debenzylated amine is formally a reduction of the amine. Thus, as shown in Equation 10.39, treatment of A -benzyl-1,23,4-tetrahydroisoquinoline dissolved in ethanol with hydrogen (H2) gas at about 1 atm pressure in the presence of aqueous hydrochloric acid (HCl(aq)) and a platinum (Pt) catalyst, results in formation of the tetrahydroisoquinoUne base (present as is hydrochloric acid salt) and toluene. 

Carbon monoxide also can be produced inside a fuel cell on the platinum surface by the reduction of CO2 [21]. This reaction requires the presence of hydrogen atoms adsorbed on the platinum (Pt) catalyst surface [7,22,23], and can be expressed as... 

Cost—PFMFCs use Platinum (Pt) catalysts, which is inherently expensive. Pt loadings for PFMFCs are coming down year after year with more development. 

One of the major reasons for the higher cost of PEMFC is due to the loading of expensive Platinum (Pt) catalyst in the electrodes. Hence the research and development activities are focused on reduced catalyst loading, use of less expensive platinum group metal (PGM) based catalyst, and development of alternate less expensive non-precious metal catalyst (other than platinum) with increased activity and durability. 

The platinum-group metals (PGMs), which consist of six elements in Groups 8— 10 (VIII) of the Periodic Table, are often found collectively in nature. They are mthenium, Ru rhodium, Rh and palladium, Pd, atomic numbers 44 to 46, and osmium. Os indium, Ir and platinum, Pt, atomic numbers 76 to 78. Corresponding members of each triad have similar properties, eg, palladium and platinum are both ductile metals and form active catalysts. Rhodium and iridium are both characterized by resistance to oxidation and chemical attack (see Platinum-GROUP metals, compounds). 

Supported bimetallic Re—Pt catalysts are important in selective reforming of petroleum. It is believed that sulhding the catalyst before use gives ReS units which act as inert diluents to reduce the size of a local ensemble of platinum atoms. Selectivity for desirable dehydrocyclization and isomerization reactions... 

AXB) shows time courees of amounts of evolved hydrogen and decalin conversions with caibon-supported platinum-based catalysts unda" supeiheated liquid-film conditions. Enhancement of dehydrogenation activities for decalin was realized by using fiiese composite catalysts. The Pt-W / C composite catalyst exhibited the hipest reaction rate at the initial stage, whereas the Pt-Re / C composite catalyst showed the second highest reaction rate in addition to low in sensitivity to retardation due to naphthaloie adsorbed on catalytic active sites [1-5], as indicated in Fig. 2(A) ). 

It was seen when studying mixed systems Pt-WOj/C and Pt-Ti02/C that with increasing percentage of oxide in the substrate mix the working surface area of the platinum crystallites increases, and the catalytic activity for methanol oxidation increases accordingly. With a support of molybdenum oxide on carbon black, the activity of supported platinum catalyst for methanol oxidation comes close to that of the mixed platinum-ruthenium catalyst. 

The phosphine-based platinum(O) catalysts do not catalyze the diboration of alkenes because of the high coordination ability of phosphine over the alkene double bond, but platinum(O) complexes without a phosphine ligand such as Pt(dba)2 [128] and Pt(cod)2 [129] are an excellent catalyst allowing the alkene insertion into the B-Pt bond under mild conditions (Scheme 1-30). The diboration of aliphatic and aromatic terminal alkenes takes place smoothly at 50°C or even at room temperature. The reaction is significantly slow for disubstituted alkenes and cyclic alkenes, but cyclic alkenes having an internal strain afford ds-diboration products in high... 

CD cinchonidine S substrate 3,4-HD 3,4-hexanedione premixing technique Tr 20 °C pm 50 bar amount of catalysts used was calculated to have equal amount of surface platinum (Pts) in each reaction. 

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