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 Uptake of Zn, Pb, Cu and Fe Ions from Spent and Unspent Engine Oil Using Termite Soil

2017 ◽  
Vol 9 (3) ◽  
pp. 85
Author(s):  
Iwekumo Agbozu ◽  
Bassey Uwem ◽  
Boisa Ndokiari
Keyword(s):  
Contact Time ◽  
Diffusion Constant ◽  
Reaction Rates ◽  
Second Order ◽  
Engine Oil ◽  
Initial Reaction ◽  
Kinetics Equation ◽  
Spent Engine Oil ◽  
Pseudo Second Order ◽  
Fe Ions

Removal of Zn, Pb, Cu and Fe ions from unspent and spent engine oil was studied using Termite soil. Process parameters such as contact time and adsorbent dosage were varied. Values from contact time were used for predicting kinetics equation of their uptake. At optimum time of 40 minutes, percentage adsorption was of the order Fe>Zn>Cu>Pb for both spent and unspent engine oil. Kinetics equation such as Elovich, Intra-particle, Pseudo-first order and Pseudo-second order were tested. Results obtained shows that their sequestering pattern fit into the pseudo-second order kinetics. Initial reaction rates, h (mg/g.min) and α (mg. g-1min-1) for all metal ions obtained from Pseudo-second order and Elovich kinetic models followed the trends Zn>Fe>Cu>Pb and Zn>Fe>Pb>Cu respectively in spent engine oil while for unspent engine oil, the trend was Fe>Zn>Cu>Pb for h (mg/g.min) and Zn>Fe>Pb>Cu for α (mg. g-1min-1). Electrostatic attraction existing on the surface of the adsorbent assisted in the high initial reaction of Zn and Fe ions, implying good affinity of the ions for the adsorbent. Desorption constant ᵦ (g/mg) was of the trend Cu>Pb>Fe>Zn and Cu>Pb>Zn>Fe for spent and unspent engine oils respectively. Intra-particle diffusion constant kid (mgg-1min-1/2) followed a similar pattern, revealing strong binding between Zn and termite soil than any of the metal ion. This pilot research has been able to suggest a kinetic process for uptake of the studied ions from spent and unspent engine oil.

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

scholarly journals Kinetics and Optimization by Response Surface Methodology of Aerobic Bioremediation. Geoelectrical Parameter Monitoring

2020 ◽  
Vol 10 (1) ◽  
pp. 405 ◽  
Author(s):  
Carla Maria Raffa ◽  
Fulvia Chiampo ◽  
Alberto Godio ◽  
Andrea Vergnano ◽  
Francesca Bosco ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Dielectric Permittivity ◽  
Response Surface ◽  
Reaction Rates ◽  
Diesel Oil ◽  
Second Order ◽  
Coaxial Cable ◽  
Oil Concentration ◽  
Two Parameters ◽  
Aerobic Bioremediation

This study aimed to investigate the kinetics of an aerobic bioremediation process of diesel oil removal by indigenous microorganisms, and to define the optimal operative conditions by means of response surface methodology. This was carried out by setting up a series of microcosms (200 g of soil), polluted with the same diesel oil concentration (70 g·kg−1 of soil), but with different water contents (u%) and carbon to nitrogen (C/N) ratios. The process was monitored by: (1) residual diesel oil concentration, to measure the removal efficiency, and (2) fluorescein production, to check the microbial activity. These two parameters were the objective variables used for the analysis of variance (ANOVA) and response surface methodology (RSM). The results allowed the interactions between u% and C/N to be defined and the optimal range to be adopted for each. The process kinetics was modeled with first- and second-order reaction rates; slightly better results were achieved for the second-order model in terms of parameter variability. Biological processes like degradation may have effects on dielectric properties of soil; an open-ended coaxial cable was used to measure the dielectric permittivity of microcosm matrices at the start and after 130 days of bioremediation. The evolution of the real and the imaginary components of dielectric permittivity provided results that supported the evidence of a biodegradation process in progress.

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.

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