Kinetic Study on the Reaction of YBa2Cu3Oy Powder with Water

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3629-3635 ◽  
Author(s):  
F. C. Yu ◽  
C. H. Lin ◽  
C. M. Wang ◽  
H.-C. I. Kao
Keyword(s):  
Activation Energy ◽  
Kinetic Study ◽  
Surface Area ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Initial Rate ◽  
Initial Surface ◽  
Exponential Factor ◽  
Rate Law

The reaction of superconducting YBa 2 Cu 3 O y powder with water is studied kinetically. The initial rate law is found as [Formula: see text] where [S] o is the initial surface area of the solid, a and b is found to be 0.94 ± 0.02 and 0.318 ± 0.002, respectively. For 100.7 mg powder with a mean radius of 0.0265 mm at pH 7.00 and 298 K, R o is 2.21 × 10-4 mol · min -1. Using a = 1 and b = 0.3, the rate constant, k, obtained at 283, 298 and 313 K is 0.64, 1.84 and 4.91 × 10-3 mol · min -1 · cm -2 · M -0.3, respectively. The activation energy is 50.0 kJ · mol -1 and pre-exponential factor is 1.09 × 106 mol · min -1 · cm -2· M -0.3, as calculated from the Arrhenius equation.

Base-catalysed reduction of pyruvic acid in near-critical water

2013 ◽  
Vol 67 (5) ◽  
Author(s):  
Li Luo ◽  
Zhi Hou ◽  
Yuan Wang ◽  
Li Dai
Keyword(s):  
Activation Energy ◽  
Formic Acid ◽  
Pyruvic Acid ◽  
Sodium Acetate ◽  
Reaction Rate ◽  
Arrhenius Equation ◽  
Base Catalyst ◽  
Acid Yield ◽  
Exponential Factor ◽  
Reaction Rate Constants

AbstractThe reduction of pyruvic acid in near-critical water has successfully been conducted under conditions of various temperatures, pressures, reaction time and the presence of formic acid as the reducing agent. In this work, additives (K2CO3, KHCO3, and sodium acetate) used in the reduction of pyruvic acid were also investigated. The results showed that by adding K2CO3 (25 mole %) a markedly higher lactic acid yield (70.7 %) was obtained than without additives (31.3 %) at 573.15 K, pressure of 8.59 MPa, 60 min, and in the presence of 2 mol L−1 formic acid. As a base catalyst, K2CO3 definitely accelerated the reduction of pyruvic acid. The reaction rate constants, average apparent activation energy and pre-exponential factor were evaluated in accordance with the Arrhenius equation. The reaction mechanism of the reduction was proposed on the basis of the experimental results.

Kinetics of Bamboo Fiber Hydrolysis Reaction in Saturated Formic Acid

2012 ◽  
Vol 531-532 ◽  
pp. 679-683 ◽  
Author(s):  
Jun Ping Zhuang ◽  
Lu Lin ◽  
Chun Sheng Pang ◽  
Ying Liu
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Formic Acid ◽  
Arrhenius Equation ◽  
Bamboo Fiber ◽  
Hydrolysis Reaction ◽  
Exponential Factor ◽  
Practical Applications ◽  
And Performance

Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the bamboo fiber kinetics is necessary. In this paper, effects of temperature and time on bamboo fiber hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The rate constants, average apparent activation energy and frequency factors were evaluated according to the Arrhenius equation. The results showed that the hydrolysis velocities of bamboo fiber were 1.63×10-2 h-1 at 55 °C, 2.59×10-2 h-1 at 60 °C, 4.56×10-2 h-1 at 65 °C, 6.75×10-2 h-1 at 70 °C and 0.10 h-1 at 75 °C in formic acid solution with 4 % hydrochloric acid. The degradation velocities of glucose were 6.57×10-3 h-1 at 55 °C, 1.98×10-2 h-1 at 60 °C, 2.53×10-2 h-1 at 65 °C, 7.47×10-2 h-1 at 70 °C and 0.14 h-1 at 75 °C. The pre-exponential factor of Arrhenius equation of bamboo fiber hydrolysis reaction and glucose decomposition was 1.48×1014 h-1 and 2.32×1020 h-1 respectively. The activation energy of bamboo fiber hydrolysis was 87.65kJ/mol, and the activation energy of glucose degradation was 141.44kJ/mol.

scholarly journals Kinetic Study of the Dissolution of Tunisian Natural Phosphate or Francolite in Industrial Phosphoric Acid

2017 ◽  
Vol 6 (1) ◽  
pp. 908-916 ◽  
Author(s):  
Ahmed CHAABOUNI
Keyword(s):  
Activation Energy ◽  
Phosphoric Acid ◽  
Kinetic Study ◽  
Rate Constant ◽  
Calcium Sulfate ◽  
Shrinking Core Model ◽  
Natural Phosphate ◽  
Rate Of Dissolution ◽  
Mineral Acids ◽  
Shrinking Core

A kinetic study of dissolution of Tunisian natural phosphate or francolite whose particles have a mesoporous texture inindustrial phosphoric acid is carried out. Therefore, We focused on the study of the influence of certain parameters thatare close to those used in plants producing phosphoric acid which are the stirring speed (300, 500 and 700 rounds perminute), concentration of phosphoric anhydride (25, 30 and 35 percent of P2O5), and the temperature (60, 70 and 80degrees Celsius); we note that the rate of dissolution of this phosphate rises by increasing the precedent parameters.Because of the complexity of the study of the dissolution of phosphate in mineral acids. Several different published kineticmodels giving different expressions of speed versus time. The shrinking core model is the appropriate model used in ourwork in a solution where there is no calcium sulfate to calculate the rate constant k and the activation energy Ea = 3.3946Kcal/mol of this phosphate.

Ionic Conductivity of Polycrystalline Li2GexSi1-xO3 (x = 0.0~1.0)

2010 ◽  
Vol 459 ◽  
pp. 27-31 ◽  
Author(s):  
Shinichi Furusawa ◽  
Shun Enokida
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Ionic Conductivity ◽  
Solid State Reaction ◽  
Arrhenius Equation ◽  
Ionic Conduction ◽  
Exponential Factor ◽  
Temperature Range

Polycrystalline Li2GexSi1-xO3 (x = 0.0~1.0) was synthesized by solid state reaction, and its ionic conductivity was studied as a function of x in a temperature range of 500–700 K. The ionic conductivity was found to depend on x and was enhanced at x = 0.2–0.7. Furthermore, the pre-exponential factor and activation energy in the Arrhenius equation were also found to depend on x. These results suggest that lithium ionic conduction in Li2GexSi1-xO3 is strongly influenced by the structure of the framework.

Kinetic Study of Sodium-Water Reaction Phenomena by Differential Thermal Analysis

2012 ◽  
Author(s):  
Shin Kikuchi ◽  
Hiroshi Seino ◽  
Akikazu Kurihara ◽  
Hiroyuki Ohshima
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Kinetic Study ◽  
Rate Constant ◽  
Reaction Temperature ◽  
Safety Assessment ◽  
Liquid Sodium ◽  
Pressurized Water ◽  
Exponential Factor

In a sodium-cooled fast reactor (SFR), if a heat transfer tube in the steam generator (SG) is failed, high pressurized water vapor blows into the liquid sodium and sodium-water reaction (SWR) takes place. SWR may cause damage to the surface of the neighboring heat transfer tubes by thermal and chemical effects. Therefore, it is important to clearly understand the SWR for safety assessment of the SG. From recent study, sodium (Na)–sodium hydroxide (NaOH) reaction as secondary surface reaction of the SWR phenomena in a SFR was identified by ab initio method [1]. However, kinetics of this reaction is a still open question. It is important to obtain quantitative rate constant of sodium monoxide (Na2O) generation by Na-NaOH reaction because Na2O may accelerate the corrosive and erosive effects. Differential thermal analysis (DTA) provides us with the valuable information on the kinetic parameters, including activation energy, pre-exponential factor (frequency factor) and reaction rate constant. Thus, kinetic study of Na–NaOH reaction has been carried out by using DTA technique. The parameters, including melting points of Na and NaOH, phase transition temperature of NaOH, Na-NaOH reaction temperature and the decomposition temperature of sodium hydride (NaH) were identified from DTA curves. Na, NaOH, and Na2O as major chemical species were observed from the X-ray diffraction (XRD) analysis of the residues after the DTA experiment. It was inferred that Na2O could be generated as a reaction product. Based on the measured reaction temperature, the first-order rate constant of Na2O generation was obtained by the application of the laws of chemical kinetics. From the estimated rate constant, it was found that Na2O generation should be considered during SWR. The results can be the basis for developing a chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by the Japan Atomic Energy Agency (JAEA) toward the safety assessment of the SG in a SFR.

Thermogravimetric Analysis of Superabsorbing Polyacrylic Hydrogel

2005 ◽  
Vol 494 ◽  
pp. 193-198 ◽  
Author(s):  
B. Janković ◽  
B. Adnadjević ◽  
J. Jovanović ◽  
D. Minić ◽  
Lj. Kolar-Anić
Keyword(s):  
Activation Energy ◽  
Distribution Function ◽  
Thermogravimetric Analysis ◽  
Weibull Distribution ◽  
Heating Rate ◽  
Rate Constant ◽  
Heating Rates ◽  
Exponential Factor ◽  
Weibull Distribution Function ◽  
Thermogravimetric Curve

The thermogravimetric analysis of superabsorbing polyacrylic hydrogel dehydration, performed under non-isothermal conditions at different heating rates was discussed. Particularly, the influence of the heating rate on the obtained results is given in detail. For this purpose the Weibull distribution function was applied. The thermogravimetric curve when the heating rate tends to zero was evaluated. The activation energy E = 63 kJ/mol, pre-exponential factor A = 2.97 × 108 min−1, and rate constant k = 2.76 × 10−3 min−1 were determined on the basis of this curve.

The Effects of Particle Size on the Kinetic Parameters in the Reaction of Nano-Nio with Sodium Bisulfate Solution

2011 ◽  
Vol 36 (4) ◽  
pp. 329-341 ◽  
Author(s):  
Yongqiang Xue ◽  
Xiaopeng Wang ◽  
Zixiang Cui
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Reaction Order ◽  
Particle Diameter ◽  
Preexponential Factor ◽  
Exponential Factor ◽  
Sodium Bisulfate

The kinetic parameters for the chemical reaction of nano-NiO of different particle sizes with aqueous sodium bisulfate solution were determined; additionally, the influence of particle size on the kinetic parameters were studied and were discussed. The results show that: there are clear effects of the particle size of nano-NiO on the rate constant, the reaction order, the apparent activation energy and the pre-exponential factor; thus the rate constant and the reaction order increase, and the apparent activation energy and the pre-exponential factor decrease, with decrease of the particle diameter; the logarithm of the preexponential factor, and the apparent activation energy, exhibit a linear relationship with the reciprocal of the particle diameter respectively. The bases of the role of the particle size are that the reaction order is influenced by the molar surface area of nano-NiO, the apparent activation energy by the molar surface energy, the preexponential factor by the molar surface entropy, and the rate constant by both the molar surface energy and the molar surface entropy.

scholarly journals Production of 1-Butyl-3-Methylimidazolium Acetate [Bmim][Ac] Using 1-Butyl-3-Methylimidazolium Chloride [Bmim]Cl and Silver Acetate: A Kinetic Study

2021 ◽  
Author(s):  
Samir I. Abu-Eishah ◽  
Saber A.A. Elsuccary ◽  
Thikrayat H. Al-Attar ◽  
Asia A. Khanji ◽  
Hifsa P. Butt ◽  
...  
Keyword(s):  
Activation Energy ◽  
Ionic Liquid ◽  
Kinetic Study ◽  
Rate Constant ◽  
Experimental Work ◽  
Silver Chloride ◽  
Reaction Rate Constant ◽  
Silver Acetate ◽  
New Process ◽  
Very High

Since most of the literature alternatives used to produce the ionic liquid 1-butyl-3-methylimidazolium acetate [Bmim][Ac] are very slow and require different solvents, we have used in this work a new process to produce the [Bmim][Ac] by the reaction of the ionic liquid 1-butyl-3-methylimidazolium chloride [Bmim]Cl with silver acetate (AgAc) where silver chloride (AgCl) precipitates as a by-product. The genuine experimental work and kinetic analyses presented here indicate that the reaction rate constant k = 7.67x1012 e(−79.285/RT). That is, the Arrhenius constant k o = 7.67x1012 L/mol.s and the activation energy E a = 79.285 kJ/mol. The very high value of the Arrhenius constant indicates that the reaction of [Bmim]Cl with silver acetate to produce [Bmim][Ac] and silver chloride is extremely fast.

scholarly journals CORRELATION BETWEEN PREEXPONENTIAL FACTOR AND ACTIVATION ENERGY OF ISOAMYLALCOHOL HYDROGENOLYSIS ON PLATINUM CATALYSTS

2010 ◽  
Vol 4 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Triyono Triyono
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Reaction Rate ◽  
Arrhenius Equation ◽  
Preexponential Factor ◽  
Active Centers ◽  
Exponential Term ◽  
Lower Activation ◽  
Higher Temperature ◽  
Lower Activation Energy

Arrhenius equation stated that reaction will proceed faster at higher temperature and with lower activation energy (Ea). Many literatures reported that preexponential factor (A) is constant for certain reaction and there is no relation between A and Ea. Experiment on the reaction of isoamylalcohol hydrogenolysis showed that logarithm of A increased linearly with Ea. The result of this investigation suggests that the rate of a process is affected by the number of active centers on the surface of a catalysts, which influences the value of the pre-exponential term in the expression for the rate constant of a reaction. An increase in the number of active centers corresponds to a higher value of A, the active centers would be less effective and is attended by a growth in the value of Ea. Therefore, reaction with lower activation energy will not always has higher reaction rate due to decreasing of Ea.   Keywords: isoamylalcohol hydrogenolysis, preexponential factor, activation  energy.

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