Catalyst surface coverages of adsorbed species in the nickel-catalyzed ethylene hydrogenation

1969 ◽  
Vol 13 (2) ◽  
pp. 215-220 ◽  
Author(s):  
I MATSUZAKI
Keyword(s):  
Catalyst Surface ◽  
Ethylene Hydrogenation ◽  
Adsorbed Species

scholarly journals Adsorption of Transition Metal Catalysts on Carbon Supports: A Theoretical Perspective

2021 ◽  
Author(s):  
Arunabhiram Chutia
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Carbon Materials ◽  
Catalyst Surface ◽  
Theoretical Perspective ◽  
Short Review ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Carbon Supports ◽  
Adsorbed Species

Adsorption is a fundamental process, which takes place on a catalyst surface before it dissociates, diffuses over the surface and recombines with other adsorbed species to form the final product. Therefore, in theoretical chemistry understanding of the local geometrical and electronic properties of the adsorbed species on the catalyst surface has been a topic of core focus. In this short review we briefly summarise some of the important developments on theoretical studies related to the adsorption properties of transition metal catalysts on graphene and graphene-related carbon materials. Prior to this, we will present a discussion on various forms of carbon materials used as catalyst supports, which will be followed by a brief discussion of the fundamentals of the density functional theory.

scholarly journals Non-Faradaic Promotion of Ethylene Hydrogenation Under Oscillating Potentials

2020 ◽  
Author(s):  
Chia Wei Lim ◽  
Max J. Huelsey ◽  
Ning Yan
Keyword(s):  
Kinetic Data ◽  
Hydrogen Adsorption ◽  
Catalyst Surface ◽  
Ethylene Hydrogenation ◽  
Promotion Effect ◽  
Ethylene Adsorption ◽  
Electric Potentials ◽  
Dynamic Enhancement ◽  
Optimized Conditions ◽  
Present Experimental Evidence

The acceleration of Faradaic reactions by oscillating electric potentials has emerged as a viable tool to enhance electrocatalysis, but the non-Faradaic dynamic promotion of thermal catalytic processes remains to be proven. Here, we present experimental evidence showing that oscillating potentials are capable of enhancing the rate of ethylene hydrogenation despite no promotion effect was observed under static potentials. The non-Faradaic dynamic enhancement reaches up to 553% on a Pd/C electrode when cycling between –0.25 VNHE and 0.55 VNHE under optimized conditions with a frequency of around 0.1 Hz and a duty cycle of 99%. Under those conditions, no stoichiometric electron transfer to ethylene can be observed, confirming the non-Faradaic nature of the process. Experiments in different electrolytes reveal a good correlation between the catalytic enhancement and the doublelayer capacitance – a measure for the interfacial electric field strength. Preliminary kinetic data suggests that cycling to a low potential increases the hydrogen adsorption on the catalyst surface while at higher potential, the ethylene adsorption and hydrogenation becomes relatively more favorable<br>

A kinetic and surface study of the oxidation of ethane by nitrous oxide and by oxygen over manganese(III) oxide

1982 ◽  
Vol 60 (7) ◽  
pp. 893-897 ◽  
Author(s):  
Craig Fairbridge ◽  
Robert Anderson Ross
Keyword(s):  
Nitrous Oxide ◽  
Infrared Spectroscopy ◽  
Catalyst Surface ◽  
Binding Energies ◽  
Adsorbed Species ◽  
X Ray ◽  
Chemisorbed Oxygen ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Oxygen Complexes

The kinetics of the nitrous oxide/ethane and oxygen/ethane reactions on manganese(III) oxide have been studied from 573 to 673 K and from 523 to 593 K, respectively. The apparent activation energy for carbon dioxide formation was 130 ± 4 kJ mol−1 in both reactions while that for nitrogen formation in the nitrous oxide/ethane reaction changed from 106 ± 4 kJ mol−1, 573–613 K, to 133 ± 4 kJ mol−, 623–673 K. The kinetic results for both reactions fit the same rate equation:[Formula: see text]where px represents either [Formula: see text]. The rate-controlling step has been associated with the interaction of adsorbed species on the catalyst surface while both ethane and the oxidising gas appear to be directly involved in further steps in the mechanism. Samples were analysed routinely by scanning electron microscopy, X-ray powder diffraction, and infrared spectroscopy. Electron spectroscopy results from samples treated in various ways with hydrocarbon/oxidant mixtures gave O(1s) values from 528.7 to 529.7 eV which are indicative of binding energies usually associated with chemisorbed oxygen. No N(1s) spectrum was obtained from catalysts exposed to hydrocarbon/nitrous oxide mixtures, in agreement with the absence of bands in the infrared which are usually associated with nitrates or nitrogen/oxygen complexes. A binding energy value of 406.5 eV was measured in the comparable N(1s) spectrum of a catalyst used at 623 K for the oxidation of ethane by nitric oxide — a result which confirms conclusions from previous surface studies on the same system using infrared spectroscopy.

scholarly journals Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies

2020 ◽  
Vol 22 (34) ◽  
pp. 18806-18814
Author(s):  
Baran Eren ◽  
Christopher G. Sole ◽  
Jesús S. Lacasa ◽  
David Grinter ◽  
Federica Venturini ◽  
...  
Keyword(s):  
Water Vapour ◽  
Catalyst Surface ◽  
Ambient Pressure ◽  
Methanol Conversion ◽  
Chemical State ◽  
Adsorbed Species ◽  
X Ray ◽  
Cu Catalyst

A model Cu catalyst surface oxidises to Cu2O when methanol, oxygen and water vapour are all present during methanol conversion.

scholarly journals Non-Faradaic Promotion of Ethylene Hydrogenation Under Oscillating Potentials

2020 ◽  
Author(s):  
Chia Wei Lim ◽  
Max J. Huelsey ◽  
Ning Yan
Keyword(s):  
Kinetic Data ◽  
Hydrogen Adsorption ◽  
Catalyst Surface ◽  
Ethylene Hydrogenation ◽  
Promotion Effect ◽  
Ethylene Adsorption ◽  
Electric Potentials ◽  
Dynamic Enhancement ◽  
Optimized Conditions ◽  
Present Experimental Evidence

The acceleration of Faradaic reactions by oscillating electric potentials has emerged as a viable tool to enhance electrocatalysis, but the non-Faradaic dynamic promotion of thermal catalytic processes remains to be proven. Here, we present experimental evidence showing that oscillating potentials are capable of enhancing the rate of ethylene hydrogenation despite no promotion effect was observed under static potentials. The non-Faradaic dynamic enhancement reaches up to 553% on a Pd/C electrode when cycling between –0.25 VNHE and 0.55 VNHE under optimized conditions with a frequency of around 0.1 Hz and a duty cycle of 99%. Under those conditions, no stoichiometric electron transfer to ethylene can be observed, confirming the non-Faradaic nature of the process. Experiments in different electrolytes reveal a good correlation between the catalytic enhancement and the doublelayer capacitance – a measure for the interfacial electric field strength. Preliminary kinetic data suggests that cycling to a low potential increases the hydrogen adsorption on the catalyst surface while at higher potential, the ethylene adsorption and hydrogenation becomes relatively more favorable<br>

Initial steps in the production of H2 from ethanol: A FT-IR study of adsorbed species on Ni/MgO catalyst surface

2007 ◽  
Vol 90 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Carlo Resini ◽  
Stefano Cavallaro ◽  
Francesco Frusteri ◽  
Salvatore Freni ◽  
Guido Busca
Keyword(s):  
Catalyst Surface ◽  
Adsorbed Species ◽  
Ft Ir ◽  
Ir Study

Complete Benzene Oxidation over Colloidal Gold Catalysts Supported on Nanostructure Zinc Oxide

2010 ◽  
Vol 96 ◽  
pp. 21-27 ◽  
Author(s):  
Hong Jing Wu ◽  
Qin Shuai ◽  
Zhen Li Zhu ◽  
Sheng Hong Hu
Keyword(s):  
Metal Oxides ◽  
Colloidal Gold ◽  
Catalyst Surface ◽  
Gold Catalysts ◽  
Benzene Oxidation ◽  
Adsorbed Species ◽  
Catalytic Activities ◽  
Gaseous Products ◽  
The Mean ◽  
Xrd Patterns

The catalytic activities of various nanometer metal oxides (ZnO, CeO2, ZrO2, Al2O3, Co3O4, MgO) supported colloidal gold catalysts with self-designed equipment were evaluated and compared for benzene catalytic oxidation. The results showed that ZnO was the most activive support of the colloidal gold among these nanometer metal oxides. The effects of Au/ZnO on the activity for benzene oxidation were investigated at 50- 300°C. The optimal gold loading was 2 wt%. The Au/ZnO was characterized using BET, XRD, and TEM methods. The XRD patterns and TEM image showed that gold nanoparticles were well dispersed on the surface of ZnO, and the mean diameter was 3.1±0.81 nm. The gaseous products of benzene oxidation and the adsorbed species on Au/ZnO catalyst surface were characterized with FTIR and GC-MS. It was proved that benzene was completely oxidized into CO2 and H2O over the Au/ZnO catalyst at low temperature.

Modeling the Electrical Double Layer to Understand the Reaction Environment in a CO2 Electrocatalytic System

2019 ◽  
Author(s):  
Divya Bohra ◽  
Jehanzeb Chaudhry ◽  
Thomas Burdyny ◽  
Evgeny Pidko ◽  
wilson smith
Keyword(s):  
Electric Field ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Surface Reaction ◽  
Catalyst Surface ◽  
Local Reaction ◽  
Reaction Diffusion ◽  
Alkali Metal Cations ◽  
Applied Potential ◽  
Critical Aspect

<p>The environment of a CO<sub>2</sub> electroreduction (CO<sub>2</sub>ER) catalyst is intimately coupled with the surface reaction energetics and is therefore a critical aspect of the overall system performance. The immediate reaction environment of the electrocatalyst constitutes the electrical double layer (EDL) which extends a few nanometers into the electrolyte and screens the surface charge density. In this study, we resolve the species concentrations and potential profiles in the EDL of a CO<sub>2</sub>ER system by self-consistently solving the migration, diffusion and reaction phenomena using the generalized modified Poisson-Nernst-Planck (GMPNP) equations which include the effect of volume exclusion due to the solvated size of solution species. We demonstrate that the concentration of solvated cations builds at the outer Helmholtz plane (OHP) with increasing applied potential until the steric limit is reached. The formation of the EDL is expected to have important consequences for the transport of the CO<sub>2</sub> molecule to the catalyst surface. The electric field in the EDL diminishes the pH in the first 5 nm from the OHP, with an accumulation of protons and a concomitant depletion of hydroxide ions. This is a considerable departure from the results obtained using reaction-diffusion models where migration is ignored. Finally, we use the GMPNP model to compare the nature of the EDL for different alkali metal cations to show the effect of solvated size and polarization of water on the resultant electric field. Our results establish the significance of the EDL and electrostatic forces in defining the local reaction environment of CO<sub>2</sub> electrocatalysts.</p>

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