scholarly journals Computational Approach for Ranking Mutant Enzymes According to Catalytic Reaction Rates

2009 ◽  
Vol 113 (11) ◽  
pp. 3579-3583 ◽  
Author(s):  
Malika Kumarasiri ◽  
Gregory A. Baker ◽  
Alexander V. Soudackov ◽  
Sharon Hammes-Schiffer
Keyword(s):  
Catalytic Reaction ◽  
Reaction Rates ◽  
Computational Approach

An algorithm for evaluating reaction rates of catalytic reaction networks with strong diffusion limitations

2001 ◽  
Vol 25 (9-10) ◽  
pp. 1185-1198 ◽  
Author(s):  
Sergio P. Bressa ◽  
Néstor J. Mariani ◽  
Néstor O. Ardiaca ◽  
Germán D. Mazza ◽  
Osvaldo M. Martı́nez ◽  
...  
Keyword(s):  
Catalytic Reaction ◽  
Reaction Rates ◽  
Reaction Networks ◽  
Diffusion Limitations ◽  
Strong Diffusion

Catalytic reaction rates in thermodynamically non-ideal systems

2000 ◽  
Vol 163 (1-2) ◽  
pp. 189-204 ◽  
Author(s):  
Rostam J. Madon ◽  
Enrique Iglesia
Keyword(s):  
Catalytic Reaction ◽  
Reaction Rates

Review of Coal-to-Synthetic Natural Gas (SNG) Production Methods and Modeling of SNG Production in an Entrained-Flow Gasifer

2016 ◽  
Author(s):  
Xijia Lu ◽  
Ting Wang
Keyword(s):  
High Temperature ◽  
Computational Model ◽  
Catalytic Reaction ◽  
Reaction Rates ◽  
Sensitivity Study ◽  
Synthetic Natural Gas ◽  
Entrained Flow ◽  
Methanation Reaction ◽  
Gasification Process ◽  
Entrained Flow Gasifier

In this paper, the coal-to-synthetic natural gas (SNG) technologies have been reviewed. Steam-oxygen gasification, hydrogasification, and catalytic steam gasification are the three major gasification processes used in coal-to-SNG production. So far, only the steam-oxygen gasification process is commercially proven by installing a catalytic methanation reactor downstream of the gasification process after syngas is produced, cleaned, and shifted to achieve an appropriate H2/CO ratio for methanation reaction. This process is expensive, less efficient, and time consuming. Ideally, it will be more effective and economic if methanation could be completed in an once-through entrained-flow gasifier. Technically, this idea is challenging because an effective gasification process is typically operated in a high-pressure and high-temperature condition, which is not favorable for methanation reaction, which is exothermic. To investigate this idea, a computational model is established and a sensitivity study of methanation reactions with and without catalysts are conducted in this study. In modeling the methanation process in a gasifier, correct information of the reaction rates is extremely important. Most of known methanation reaction rates are tightly linked to the catalysts used. Since the non-catalytic reaction rates for methanation are not known in a gasifer and the issues are compounded by the fact that inherent minerals in coal ashes can also affect the methanation kinetics, modeling of methanation in an entrained-flow gasifier becomes very challenging. Considering these issues, instead of trying to obtain the correct methnation reaction rate, this study attempts to use computational model as a convenient tool to investigate the sensitivity of methane production under a wide range methanation reaction rates with and without catalysts. From this sensitivity study, it can be learned that the concept of implementing direct methanation in a once-through entrained-flow gasifier may not be attractive due to competitions of other reactions in a high-temperature environment. The production of SNG is limited to about 18% (vol) with catalytic reaction with a pre-exponential factor A in the order of 107. A further increase of the value of A to 1011 doesn’t result in more production of SNG. This SNG production limit could be caused by the high-temperature and short residence time (3–4 seconds) in the entraind-flow gasifier.

Time-resolved observation of V2O5/TiO2 in NH3-SCR reveals the equivalence of Brønsted and Lewis acid sites

2020 ◽  
Vol 56 (98) ◽  
pp. 15450-15453
Author(s):  
Inhak Song ◽  
Hwangho Lee ◽  
Se Won Jeon ◽  
Taejin Kim ◽  
Do Heui Kim
Keyword(s):  
Lewis Acid ◽  
Catalytic Reaction ◽  
Reaction Rates ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Time Resolved ◽  
Nh3 Scr ◽  
Brønsted And Lewis Acid

Reaction rates of Lewis-NH3 and Brønsted-NH3 species were measured to be equivalent in the selective catalytic reaction over V2O5/TiO2 catalyst.

Spectroelectrochemical measurements of second-order catalytic reaction rates using signal averaging

1970 ◽  
Vol 74 (17) ◽  
pp. 3231-3236 ◽  
Author(s):  
Henry N. Blount ◽  
Nicholas Winograd ◽  
Theodore Kuwana
Keyword(s):  
Catalytic Reaction ◽  
Reaction Rates ◽  
Second Order ◽  
Signal Averaging

scholarly journals Catalytic reaction of cytokinin dehydrogenase: preference for quinones as electron acceptors

2004 ◽  
Vol 380 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Jitka FRÉBORTOVÁ ◽  
Marco W. FRAAIJE ◽  
Petr GALUSZKA ◽  
Marek ŠEBELA ◽  
Pavel PEČ ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Catalytic Reaction ◽  
Oxidative Degradation ◽  
Reaction Rates ◽  
Electron Acceptors ◽  
Cytokinin Oxidase ◽  
Turnover Rates ◽  
Isopentenyl Adenine ◽  
Covalently Linked ◽  
Strict Specificity

The catalytic reaction of cytokinin oxidase/dehydrogenase (EC 1.5.99.12) was studied in detail using the recombinant flavoenzyme from maize. Determination of the redox potential of the covalently linked flavin cofactor revealed a relatively high potential dictating the type of electron acceptor that can be used by the enzyme. Using 2,6-dichlorophenol indophenol, 2,3-dimethoxy-5-methyl-1,4-benzoquinone or 1,4-naphthoquinone as electron acceptor, turnover rates with N6-(2-isopentenyl)adenine of approx. 150 s−1 could be obtained. This suggests that the natural electron acceptor of the enzyme is quite probably a p-quinone or similar compound. By using the stopped-flow technique, it was found that the enzyme is rapidly reduced by N6-(2-isopentenyl)adenine (kred=950 s−1). Re-oxidation of the reduced enzyme by molecular oxygen is too slow to be of physiological relevance, confirming its classification as a dehydrogenase. Furthermore, it was established for the first time that the enzyme is capable of degrading aromatic cytokinins, although at low reaction rates. As a result, the enzyme displays a dual catalytic mode for oxidative degradation of cytokinins: a low-rate and low-substrate specificity reaction with oxygen as the electron acceptor, and high activity and strict specificity for isopentenyladenine and analogous cytokinins with some specific electron acceptors.

The contribution of proximity and orientation to catalytic reaction rates

Biopolymers ◽  
1973 ◽  
Vol 12 (7) ◽  
pp. 1689-1704 ◽  
Author(s):  
Charles Delisi ◽  
Donald M. Crothers
Keyword(s):  
Catalytic Reaction ◽  
Reaction Rates
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