Polycyclic aromatic hydrocarbons--catalysts for molecular hydrogen formation
Abstract:
Polycyclic aromatic hydrocarbons (PAHs) have been shown to catalyse molecular hydrogen formation. The process occurs via atomic hydrogen addition reactions leading to the formation of super-hydrogenated PAH species, followed by molecular hydrogen forming abstraction reactions. Here, we combine quadrupole mass spectrometry data with kinetic simulations to follow the addition of deuterium atoms to the PAH molecule coronene. When exposed to sufficiently large D atom fluences, coronene is observed to be driven towards the completely deuterated state (C24D36) with the mass distribution peaking at 358 amu, just below the peak mass of 360 amu. Kinetic models reproduce the experimental observations for an abstraction cross-section of sigma(abs) = 0.01 angstroms2 per excess H/D atom, and addition cross-sections in the range of sigma(add) = 0.55-2.0 angstroms2 for all degrees of hydrogenation. These findings indicate that the cross-section for addition does not scale with the number of sites available for addition on the molecule, but rather has a fairly constant value over a large interval of super-hydrogenation levels.
More Related Videos
10:19Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation
Published on: July 18, 2017
08:40Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production
Published on: December 6, 2021
Related Concept Videos
Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Catalysis
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Heterogeneous Catalysis
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
