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>

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>

HYDROGEN CHEMISORPTION ON NICKEL–MAGNESIA CATALYSTS

1963 ◽  
Vol 41 (1) ◽  
pp. 68-73 ◽  
Author(s):  
N. Ramasubramanian ◽  
L. M. Yeddanapalli
Keyword(s):  
Kinetic Data ◽  
Pressure Range ◽  
Hydrogen Adsorption ◽  
Catalyst Surface ◽  
Hydrogen Chemisorption ◽  
Oxygen Contamination ◽  
Different Types ◽  
Elovich Equation ◽  
Temperature And Pressure ◽  
Oxygen Addition

The hydrogen adsorption activities, per gram of nickel, of two nickel–magnesia catalysts are compared and explained on the basis of different types of nickel being present. The application of the Elovich equation to interpret the kinetic data shows the possibility of the presence of three kinetic stages in the temperature and pressure range studied. A study of the effect, on the hydrogen adsorption, of deliberate oxygen addition to and re-reduction of the catalyst surface shows that the nature of the oxygen contamination in the catalyst is different from that of the added oxygen.

The sorption of copper on almond shell: optimization and kinetics

2011 ◽  
Vol 63 (7) ◽  
pp. 1389-1395 ◽  
Author(s):  
S. Aber ◽  
D. Salari ◽  
B. Ayoubi Feiz
Keyword(s):  
Kinetic Data ◽  
Contact Time ◽  
Correlation Coefficients ◽  
Copper Removal ◽  
Order Model ◽  
Almond Shell ◽  
Initial Concentration ◽  
Pseudo Second Order ◽  
Shell Optimization ◽  
Optimized Conditions

Batch sorption studies using almond shell as an sorbent for the removal of Cu (II) from aqueous solutions, showed that copper removal decreased from 74.9% to 45.6% with increasing its concentration from 10 to 70 ppm. The removal increased with increasing sorbent dose and pH, respectively. Copper removal was obtained equal to 63.7%, 69.6% and 58.6% at 26˚C, 40˚C and 55˚C. The sorption of Cu (II) on almond shell was also optimized by Taguchi method. The optimized conditions were the sorbent mass of 4 g, the ion initial concentration of 10 ppm, pH 7, the temperature of 40˚C and contact time equal to 60 min. The pH and initial Cu (II) concentration with respectively 32.75% and 31.20% contribution had more influence on the removal of Cu (II). The kinetic data fit pseudo-second-order model with correlation coefficients greater than 0.99 and rate constants in the range of 0.26–7.87 g mg−1 min−1.

Ethylene Hydrogenation on a Platinum Nanocoating at Various Electric Potentials

2017 ◽  
Vol 11 (6) ◽  
pp. 932-936 ◽  
Author(s):  
V. N. Korchak ◽  
M. V. Grishin ◽  
M. Ya. Bykhovskii ◽  
A. K. Gatin ◽  
V. G. Slutskii ◽  
...  
Keyword(s):  
Ethylene Hydrogenation ◽  
Electric Potentials

Estimation of the catalyst pellet activity distribution from experimental kinetic data

1989 ◽  
Vol 54 (2) ◽  
pp. 388-399 ◽  
Author(s):  
Alena Brunovská ◽  
Bibiana Remiarová ◽  
Carlo Lebrun
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Gradient Method ◽  
Kinetic Data ◽  
Adjoint Equation ◽  
Ethylene Hydrogenation ◽  
Activity Distribution ◽  
Catalyst Pellet ◽  
Single Pellet ◽  
Scanning Electron

In this paper a method of catalyst pellet activity distribution estimation from experimental kinetic data is described. Measurements of outlet concentration from a laboratory continuous stirred single-pellet reactor vs feed rate for ethylene hydrogenation on Pt/alumina pellet are used as kinetic data. To find the best estimate the gradient method is employed and the gradient is computed with the help of the adjoint equation. The estimated activity distribution is compared with the Pt distribution obtained by the scanning electron microscope.

THE INTERACTION OF METHANE AND METHANE-d4 ON NICKEL AND THE STATE OF THE CATALYST SURFACE

1949 ◽  
Vol 27b (4) ◽  
pp. 303-317 ◽  
Author(s):  
Maurice M. Wright ◽  
Hugh S. Taylor
Keyword(s):  
Kinetic Data ◽  
Surface Reaction ◽  
Catalyst Surface ◽  
Dissociative Adsorption ◽  
Fischer Tropsch ◽  
Heats Of Adsorption ◽  
First Order ◽  
First Order Kinetics ◽  
Surface Equilibrium ◽  
Adsorption Of Methane

The interaction of methane and methane-d4 on nickel has been re-examined. The data strengthen the previous concept of a dissociative adsorption of methane on the catalyst. The kinetic data indicate first-order disappearance of methane-d4 with an activation energy of 20.9 kcal. between 100° and 255 °C. Poisoning by carbonaceous residues occurs at all temperatures. First-order kinetics are indicated for the formation of methane-d3 and methane-d2 on the catalyst surface. Reaction of hydrogen with surface residues, after an exchange reaction, indicate that CX, CX2, and CX3 fragments are present on the surface where X is H or D. Higher temperatures favor an equilibrium between these fragments on the surface, equilibrium being displaced towards CX3 as temperature increases. This equilibrium will be dependent on the heats of adsorption of the fragments and of hydrogen on the surface and therefore involves also the metal used as catalyst. The data suggest a basic approach to the mechanism of the Fischer–Tropsch synthesis on metal catalysts.

scholarly journals The Influence of Carbon Nature on the Catalytic Performance of Ru/C in Levulinic Acid Hydrogenation with Internal Hydrogen Source

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5362
Author(s):  
Marcin Jędrzejczyk ◽  
Emilia Soszka ◽  
Joanna Goscianska ◽  
Marcin Kozanecki ◽  
Jacek Grams ◽  
...  
Keyword(s):  
Grain Size ◽  
Levulinic Acid ◽  
Carbon Materials ◽  
Hydrogen Adsorption ◽  
Catalyst Surface ◽  
Catalytic Performance ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Materials Used ◽  
The Relationship

The influence of the nature of carbon materials used as a support for Ru/C catalysts on levulinic acid hydrogenation with formic acid as a hydrogen source toward gamma-valerolactone was investigated. It has been shown that the physicochemical properties of carbon strongly affect the catalytic activity of Ru catalysts. The relationship between the hydrogen mobility, strength of hydrogen adsorption, and catalytic performance was established. The catalyst possessing the highest number of defects, stimulating metal support interaction, exhibited the highest activity. The effect of the catalyst grain size was also studied. It was shown that the decrease in the grain size resulted in the formation of smaller Ru crystallites on the catalyst surface, which facilitates the activity.

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