Platinum hydrogen reaction

The composition of a reforming catalyst is dictated by the composition of the feedstock and the desired reformate. The catalysts used are principally platinum or platinum—rhenium on an alumina base. The purpose of platinum on the catalyst is to promote dehydrogenation and hydrogenation reactions. Nonplatinum catalysts are used in regenerative processes for feedstocks containing sulfur, although pretreatment (hydrodesulfurization) may permit platinum catalysts to be employed. 

Hydrogenation Reactions. Hydrogen over a nickel, platinum, or paladium catalyst can partially or totally saturate the aromatic ring. Thermal hyrogenolysis of toluene yields benzene, methane, and biphenyl. 

The ability of palladium and platinum to catalyse hydrogenation reactions is of considerable industrial importance. 

Addition of fresh platinum oxide catalyst to a hydrogenation reaction in acetic acid caused immediate explosion. Several similar incidents, usually involving acetic acid as solvent, are known to the author. 

Hydrosilylation turned out to be a unique method in organosilicone chemistry, but in some cases it suffers from severe side reactions. An explanation is provided by the generally accepted reaction mechanism known as "Chalk-Harrod mechanism" described elsewhere [7]. Included in this series of reaction steps is an insertion of olefmic ligands into a platinum-hydrogen bond. Since the metal may be bonded to either of the unsaturated carbon atoms and the reaction is also an equilibrium, alkenes may result which are in fact isomerized starting material. Isomeric silanes are to be expected as well (Eq. 1), along with 1-hexylsilane, which is by far, the main compound produced. 

The alkaloid adsorbed on the platinum surface could form a tridimensional space within which the hydrogenation reaction can preferentially occur, due to a close interaction with QN. This space was called chiral pocket in analogy to biological systems that show high differentiation ability due to shape discrimination (Figure 14.11). 

Like platinum, it is used as a catalyst in several hydrogenation reactions. It absorbs hydrogen to a much greater extent than platinum. When heated to dull redness, it absorbs about 1000 times its own volume of hydrogen. If the temperature is raised further, the hydrogen is expelled. In the process probably the hydrogen molecules are broken into hydrogen atoms which then fit into the palladium lattice. 

Cathode Platinum metals, especially platinum and palladium, achieve the lowest known overvoltages for hydrogen. Moreover, they are effective catalysts for hydrogenation reactions [15]. 

Zhao et al (70) developed a method for the synthesis of dendrimer-encapsulated metal nanoparticles based on sorbing metal ions into (modified) PAMAM dendrimers followed by a reduction. Dendrimers encapsulating copper, palladium, and platinum nanoparticles have been prepared. Hydroxyl-terminated PAMAM dendrimers were used to prepare encapsulated palladium (PAMAM generations 4, 6, and 8) and platinum (PAMAM generations 4 and 6) nanoparticles. The dendrimer-encapsulated palladium and platinum nanocomposites catalyzed the hydrogenation reaction of allyl alcohol and N-isopropyl acrylamide in water 71). 

Platinum dioxide, also known as Adams catalyst, is used commercially in many hydrogenation reactions at ordinary temperatures, such as reduction of olefinic and acetylenic unsaturation, aromatics, nitro, and carbonyl groups. 

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