Quantum Mechanical Basis for Kinetic Diameters of Small Gaseous Molecules

Mehio, Nada; Dai, Sheng; Jiang, De‐en

doi:10.1021/jp412588f

Cited by 239 publications

(177 citation statements)

References 44 publications

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“…The difference in drying with air or hydrogen is pronounced only for 5Ni/13X probably due to the bigger pores of this support, which allows easier diffusion and release of the air and water molecules. In the drying step, kinetic diameters of the molecules involved reach 3.6 A for nitrogen and 3.5 A for oxygen, respectively [25]. Although this is small enough to enter the 5 A pores of the 5A structure, it is clear that the 9 A pores of the 13X structure allow for a faster transport of these molecules.…”

Section: Resultsmentioning

confidence: 97%

Development of improved nickel catalysts for sorption enhanced CO2 methanation

Delmelle

Duarte

Franken

et al. 2016

International Journal of Hydrogen Energy

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a b s t r a c tSorption enhanced CO 2 methanation is a complex process in which the key challenge lies in the combined optimization of the catalyst activity and water adsorption properties of the zeolite support. In the present work, improved nickel-based catalysts with an enhanced water uptake capacity were designed and catalytically investigated. Two different zeolite frameworks were considered as supports for nanostructured Ni, and studied with defined operation parameters. 5Ni/13X shows significantly increased, nearly three-fold higher, operation time in the sorption enhanced CO 2 methanation mode compared to the reference 5Ni/5A, likely due to its higher water sorption capacity. Both catalysts yield comparable CO 2 conversion in conventional CO 2 methanation (without water uptake). Regeneration of the catalysts performance is possible via a drying step between methanation cycles under both reducing and oxidizing atmospheres; however, operation time of 5Ni/13X increases further after drying under air.

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Section: Resultsmentioning

confidence: 97%

Development of improved nickel catalysts for sorption enhanced CO2 methanation

Delmelle

Duarte

Franken

et al. 2016

International Journal of Hydrogen Energy

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“…As only the pore areas contribute to hydrogen transmission, we defined a fractional parameter in the permeance calculations , where Å is the kinetic diameter of H 2 or D 2 molecule 35 and a is the lattice constant of the strained C 2 N- h 2D. Therefore, the D 2 permeance is where p ( T ) is the thermally-weighted transmission that has to be numerically evaluated via Eq.…”

Section: Resultsmentioning

confidence: 99%

Efficient hydrogen isotopologues separation through a tunable potential barrier: The case of a C2N membrane

Zhao

2017

Sci Rep

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Isotopes separation through quantum sieving effect of membranes is quite promising for industrial applications. For the light hydrogen isotopologues (eg. H2, D2), the confinement of potential wells in porous membranes to isotopologues was commonly regarded to be crucial for highly efficient separation ability. Here, we demonstrate from first-principles that a potential barrier is also favorable for efficient hydrogen isotopologues separation. Taking an already-synthesized two-dimensional carbon nitride (C2N-h2D) as an example, we predict that the competition between quantum tunneling and zero-point-energy (ZPE) effects regulated by the tensile strain leads to high selectivity and permeance. Both kinetic quantum sieving and equilibrium quantum sieving effects are considered. The quantum effects revealed in this work offer a prospective strategy for highly efficient hydrogen isotopologues separation.

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“…To unravel the effects of these limitations, the performances of the Lindlar and NanoSelect TM catalysts have been evaluated in the hydrogenation of acetylenes of varying adsorption length. Particularly, the adsorption length has been obtained from the density isocontour46 and is defined as the size of the hydrocarbon when the triple bond is activated on palladium. In fact, as shown in Figure S9 in the Supporting Information, this length differs from that of the molecule when the CC unsaturation is not activated.…”

Section: Resultsmentioning

confidence: 99%

From the Lindlar Catalyst to Supported Ligand‐Modified Palladium Nanoparticles: Selectivity Patterns and Accessibility Constraints in the Continuous‐Flow Three‐Phase Hydrogenation of Acetylenic Compounds

Vilé

Almora‐Barrios

Mitchell

et al. 2014

Chemistry A European J

147

127

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Site modification and isolation through selective poisoning comprise an effective strategy to enhance the selectivity of palladium catalysts in the partial hydrogenation of triple bonds in acetylenic compounds. The recent emergence of supported hybrid materials matching the stereo- and chemoselectivity of the classical Lindlar catalyst holds promise to revolutionize palladium-catalyzed hydrogenations, and will benefit from an in-depth understanding of these new materials. In this work, we compare the performance of bare, lead-poisoned, and ligand-modified palladium catalysts in the hydrogenation of diverse alkynes. Catalytic tests, conducted in a continuous-flow three-phase reactor, coupled with theoretical calculations and characterization methods, enable elucidation of the structural origins of the observed selectivity patterns. Distinctions in the catalytic performance are correlated with the relative accessibility of the active site to the organic substrate, and with the adsorption configuration and strength, depending on the ensemble size and surface potentials. This explains the role of the ligand in the colloidally prepared catalysts in promoting superior performance in the hydrogenation of terminal and internal alkynes, and short-chain alkynols. In contrast, the greater accessibility of the active surface of the Pd-Pb alloy and the absence of polar groups are shown to be favorable in the conversion of alkynes containing long aliphatic chains and/or ketone groups. These findings provide detailed insights for the advanced design of supported nanostructured catalysts.

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Quantum Mechanical Basis for Kinetic Diameters of Small Gaseous Molecules

Cited by 239 publications

References 44 publications

Development of improved nickel catalysts for sorption enhanced CO2 methanation

Development of improved nickel catalysts for sorption enhanced CO2 methanation

Efficient hydrogen isotopologues separation through a tunable potential barrier: The case of a C2N membrane

From the Lindlar Catalyst to Supported Ligand‐Modified Palladium Nanoparticles: Selectivity Patterns and Accessibility Constraints in the Continuous‐Flow Three‐Phase Hydrogenation of Acetylenic Compounds

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