Molecular kinetics of heterogeneous catalytic reactions

Santen, van Ra Rutger; Runstraat, van de A; Gelten, RJ

doi:10.1016/s0167-2991(97)80398-9

Cited by 4 publications

(4 citation statements)

References 21 publications

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“…If another hydrogen is added (CH 2 /Fe), the hydrogens and the carbon show a similar electric charge to the previous case, but the electrical charge of the catalyst and the adsorption energy change significantly (0.204 a.u. ) which is in agreement with a decrease in the overlap between C and the surface, which facilitates the subsequent desorption of final products [27][28][29]. During hydrogenation steps, the catalyst not only provides support to the adsorbed species, but also transfers charge in order for the reaction to occurs.…”

Section: Resultssupporting

confidence: 72%

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Influence of coadsorbed H in CO dissociation and CHn formation on Fe(100): A DFT study

Amaya-Roncancio

Linares

Sapag

et al. 2015

Applied Surface Science

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Section: Resultssupporting

confidence: 72%

“…Adsorption sites can play an important role in adsorption, desorption and reaction of products. Particularly, bridge and atop sites are places where transitory species may capture H to form products and desorb [22,[25][26][27][28][29].…”

Section: Resultsmentioning

confidence: 99%

Influence of coadsorbed H in CO dissociation and CHn formation on Fe(100): A DFT study

Amaya-Roncancio

Linares

Sapag

et al. 2015

Applied Surface Science

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“…When pores are at saturation loading, molecular exchange between gas phase and adsorbed phase will be too slow to bring the adsorbed phase to gas-phase chemical equilibrium [22,23,25,26]. Instead, the adsorbed phase will exhibit an intracrystalline chemical equilibrium as defined by the intracrystalline Gibbs free energies of formation of the various isomers [21,24].…”

Section: Catalysis: Impact Of C 16 Adsorption Thermodynamicsmentioning

confidence: 99%

“…In a recent attempt to come up with a more systematic approach to shape selectivity we suggested that molecular sieves impose a chemical equilibrium on adsorbed molecules that is different from that in the gas phase [17,[21][22][23][24]. In sieves with relatively small pores, and, therefore, predominantly molecule-wall interactions, the imposed chemical equilibrium could be successfully ascertained by simulations at low loading [17,21].…”

Section: Introductionmentioning

confidence: 99%

Shape selectivity through entropy

Schenk

2003

Journal of Catalysis

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Based on a comparison between measured and simulated adsorption properties, we demonstrate that a decrease in the Gibbs free energy of formation and adsorption-due to higher adsorption entropy-satisfactorily explains the selective production and adsorption of the most compact, branched paraffins in n-hexadecane hydroconversion in molecular sieves with pore diameters of ∼ 0.75 nm. Adsorption entropy is important because the pores are saturated with reactant, and because the adsorbed phase is not at gas-phase chemical equilibrium. This explanation supplants the traditional kinetic explanation involving changes in the Gibbs free energy of formation of the relevant transition states. Instead, we attribute the effect of molecular sieve structure on the branched paraffin yield to a redirection of the hydroisomerization reactions away from the gas-phase chemical equilibrium distribution, commensurate with the Gibbs free energy of adsorption of the isomers inside the pores. These shape-selective changes to the reaction rates appear to be as ubiquitous as those originating from steric constraints imposed on intracrystalline diffusion and reaction rates. This would make adsorption-induced changes in the Gibbs free energy of formation of reactants, intermediates, and products a missing cornerstone in traditional shape selectivity theory.

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