Temperature-Dependent Kinetics and Reaction Mechanism of Ammonia Oxidation on Pt, Ir, and PtIr Alloy Catalysts

2018 ◽  
Vol 165 (15) ◽  
pp. J3095-J3100 ◽  
Author(s):  
Liang Song ◽  
Zhixiu Liang ◽  
Zhong Ma ◽  
Yu Zhang ◽  
Jingyi Chen ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Ammonia Oxidation ◽  
Temperature Dependent ◽  
Alloy Catalysts

Active chlorine mediated ammonia oxidation revisited: Reaction mechanism, kinetic modelling and implications

2018 ◽  
Vol 145 ◽  
pp. 220-230 ◽  
Author(s):  
Changyong Zhang ◽  
Di He ◽  
Jinxing Ma ◽  
T. David Waite
Keyword(s):  
Reaction Mechanism ◽  
Ammonia Oxidation ◽  
Kinetic Modelling ◽  
Active Chlorine

THE SILVER CATALYZED OXIDATION OF ETHYLENE: IV. REACTION MECHANISM

1954 ◽  
Vol 32 (4) ◽  
pp. 443-451 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Reaction Mechanism ◽  
Ethylene Oxide ◽  
Temperature Dependent ◽  
Heterogeneous Oxidation ◽  
Initial Oxidation ◽  
Partial Pressures ◽  
Parallel Reactions ◽  
Single Oxygen ◽  
Catalyzed Oxidation ◽  
Adsorbed Ethylene

A reaction mechanism for the silver catalyzed oxidation of C2H4 by oxygen has been formulated which is consistent with kinetic data for this system. It is suggested that both ethylene oxide and CO2 formation involve interaction of single gaseous C2H4 molecules with single oxygen adatoms. This may be a system of two parallel reactions of different activation energy requirements or a common initiation step to form adsorbed ethylene oxide which may then desorb immediately or isomerize to acetaldehyde followed by rapid oxidation to CO2 and H2O. Account is taken of the known adsorption characteristics of O2 on silver to deduce expressions for initial rates of ethylene oxide and CO2 formation as a function of reactant partial pressures. The generalized form of the equation is r = k(1 + a/pE + b/pO)−1, where k, a, and b are temperature dependent constants and pE and pO are partial pressures of ethylene and of oxygen respectively.A mechanism is also suggested for the heterogeneous oxidation of ethylene oxide which involves interaction between a gas phase ethylene oxide molecule and a single oxygen adatom to form an intermediate (probably formaldehyde) which is rapidly oxidized to CO2 and H2O. A similar expression to that above for the initial oxidation rate is deduced. These expressions have been fitted successfully to experimental data.

New Insights into Reaction Mechanism of Selective Catalytic Ammonia Oxidation Technology for Diesel Aftertreatment Applications

2011 ◽  
Vol 4 (1) ◽  
pp. 1810-1821 ◽  
Author(s):  
Krishna Kamasamudram ◽  
Aleksey Yezerets ◽  
Xu chen ◽  
Neal Currier ◽  
Mario Castagnola ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Ammonia Oxidation ◽  
Oxidation Technology

(Invited) Temperature-Dependent Kinetic Study of Ammonia Oxidation Reaction on Gas Diffusion Electrodes in NH3-Saturated 1 M KOH Solutions

2018 ◽  
Vol 85 (12) ◽  
pp. 161-165
Author(s):  
Zhixiu Liang ◽  
Liang Song ◽  
Zhong Ma ◽  
Yu Zhang ◽  
Radoslav R. Adzic ◽  
...  
Keyword(s):  
Kinetic Study ◽  
Oxidation Reaction ◽  
Ammonia Oxidation ◽  
Gas Diffusion ◽  
Gas Diffusion Electrodes ◽  
Temperature Dependent

scholarly journals 3-Hydroxy-3-methylglutaryl-coenzyme A synthase from ox liver. Properties of its acetyl derivative

1985 ◽  
Vol 227 (2) ◽  
pp. 601-607 ◽  
Author(s):  
D M Lowe ◽  
P K Tubbs
Keyword(s):  
Reaction Mechanism ◽  
Half Life ◽  
Thiol Group ◽  
Acetyl Derivative ◽  
Cysteine Residue ◽  
Temperature Dependent ◽  
Acetyl Coa ◽  
Maximum Value ◽  
Affinity Labelling ◽  
Acetyl Group

Ox liver mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (EC 4.1.3.5) reacts with acetyl-CoA to form a complex in which the acetyl group is covalently bound to the enzyme. This acetyl group can be removed by addition of acetoacetyl-CoA or CoA. The extent of acetylation and release of CoA were found to be highly temperature-dependent. At temperatures above 20 degrees C, a maximum value of 0.85 mol of acetyl group bound/mol of enzyme dimer was observed. Below this temperature the extent of rapid acetylation was significantly lowered. Binding stoichiometries close to 1 mol/mol of enzyme dimer were also observed when the 3-hydroxy-3-methylglutaryl-CoA synthase activity was titrated with methyl methanethiosulphonate or bromoacetyl-CoA. This is taken as evidence for a ‘half-of-the-sites’ reaction mechanism for the formation of 3-hydroxy-3-methylglutaryl-CoA by 3-hydroxy-3-methylglutaryl-CoA synthase. The Keq. for the acetylation was about 10. Isolated acetyl-enzyme is stable for many hours at 0 degrees C and pH 7, but is hydrolysed at 30 degrees C with a half-life of 7 min. This hydrolysis is stimulated by acetyl-CoA and slightly by succinyl-CoA, but not by desulpho-CoA. The site of acetylation has been identified as the thiol group of a reactive cysteine residue by affinity-labelling with the substrate analogue bromo[1-14C]acetyl-CoA.

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