Kinetics of 2-Chloro-6-Nitrotoluene Hydrogenation on Palladium/Carbon Catalyst without Inhibitors

2012 ◽  
Vol 487 ◽  
pp. 107-110
Author(s):  
Feng Wen ◽  
Yi Feng Zhu ◽  
Xiao Nian Li
Keyword(s):  
Activation Energy ◽  
High Selectivity ◽  
Hydrogenation Reaction ◽  
Zero Order ◽  
Carbon Catalyst ◽  
Free Condition ◽  
Solvent Free Condition ◽  
Favorable Conditions ◽  
Kinetics Of ◽  
Very High

Pd-only catalyst supported on activated carbon has been prepared by chemical impregnation and used to catalyze the hydrogenation of 2-chloro-6-nitrotoluene (2-CNT) to 3-chloro-2-methylaniline in solvent-free condition. The effects of reaction temperature，H2 pressure on the hydrogenation have been investigated. The reaction showed very high selectivity with the dehalogenation side product with a yield of less than 1.2 %. The most favorable conditions could be temperature= 353 K, stirring speed= 1200 rpm, H2 pressure= 1 MPa. The catalytic hydrogenation reaction was found to have a zero order with hydrogen and 1 order with 2-CNT. The apparent activation energy of the hydrogenation was 60.58 kJ/mol.

Kinetics of ο-Chloronitrobenzene Hydrogenation on Palladium/Carbon Catalyst

2011 ◽  
Vol 239-242 ◽  
pp. 161-167
Author(s):  
Xiao Zhen Wang ◽  
Yi Feng Zhu ◽  
Xiao Nian Li
Keyword(s):  
High Selectivity ◽  
Total Yield ◽  
Hydrogenation Reaction ◽  
Commercial Application ◽  
Reaction Conditions ◽  
Solvent Free Conditions ◽  
Hydrogenation Kinetics ◽  
Favorable Reaction ◽  
Kinetics Of ◽  
Very High

A 2 wt % Pd/C catalyst has been prepared by chemical impregnation and used to catalyze the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) in solvent-free conditions. The effects of reaction temperature, H2 pressure, and stirring intensity on the hydrogenation kinetics have been investigated. The hydrogenation reaction showed very high selectivity with dehalogenation side products as low as 0.3% of total yield. The favorable reaction conditions were found to be temperature T = 383 K, stirring speed = 900 rpm, and feeding ratio CNB/catalyst = 200/1 (m/m). The recycled Pd/C still retained more than 98% of its original selectivity after 12 repeat used, indicating the catalyst had strong potentials for commercial application at industrial scale.

4-Hydroxy Pyridinium Triflate@SiO2 Nanoparticles as a Novel Efficient Catalyst for Fries Rearrangement of Aryl Esters with High Selectivity

2020 ◽  
Vol 17 (8) ◽  
pp. 654-660
Author(s):  
Shermineh Sadat Ghalehbandi ◽  
Dadkhoda Ghazanfari ◽  
Sayed Ali Ahmadi ◽  
Enayatollah Sheikhhosseini
Keyword(s):  
High Selectivity ◽  
Sio2 Nanoparticles ◽  
High Yield ◽  
Synthetic Method ◽  
Functionalized Silica ◽  
Efficient Catalyst ◽  
Fries Rearrangement ◽  
Free Condition ◽  
Solvent Free Condition ◽  
Work Up

Introduction: We developed a simple, fast and new method for the Fries rearrangement of aryl esters. Materials and Methods: 4-Hydroxy pyridinium triflate functionalized silica is a very efficient, reusable and economically available catalyst for the Fries rearrangement in solvent-free condition and under microwave irradiation. Results and Discussion: Also, a notable selectivity was observed in the presence of 4-hydroxy pyridinium triflate functionalized silica. Conclusion: Selectivity, shorter reaction time, high yield, and easy work-up are advantages of this synthetic method.

Chemical Vapor Deposition of SiO2 from Ozone-Organosilane Mixtures near Atmospheric Pressure

1992 ◽  
Vol 282 ◽  
Author(s):  
K. V. Guinn ◽  
J. A. Mucha
Keyword(s):  
Activation Energy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Zero Order ◽  
Kcal Mole ◽  
Consumption Ratio ◽  
Zero Order Kinetics ◽  
Kinetics Of

ABSTRACTThe kinetics of deposition of SiO2 by the reaction of tetramethylsilane (TMS) with ozone (O3) has been studied over the temperature range 180 – 380° C and compared with available data for the same process using tetraethoxysilane (TEOS). Both processes exhibit the same activation energy (17 kcal/mole) below 300 ° C which falls-off at higher temperatures due to transport limitations. Transition from first- to zero-order kinetics occurs with increasing concentrations of TMS and O3, which gives an overall O3/TMS consumption ratio of 10 at 258° C and5 at 325° C. TEOS is estimated to be 5 times more reactive than TMS above 300° C and over 10 times more reactive in the kinetically-limited regime below 300° C. Results suggest that O3-induced SiO2 deposition proceeds via surface reactions and is limited by heterogeneous decomposition of ozone.

Kinetics of monoammonium phosphate-induced potassium release from selected soils

1995 ◽  
Vol 75 (2) ◽  
pp. 197-203 ◽  
Author(s):  
J. M. Zhou ◽  
P. M. Huang
Keyword(s):  
Phosphate Fertilizer ◽  
Zero Order ◽  
Rate Coefficients ◽  
Monoammonium Phosphate ◽  
Major Mechanism ◽  
Zero Order Kinetics ◽  
Potassium Dynamics ◽  
Kinetics Of ◽  
Very High ◽  
K Release

When monoammonium phosphate fertilizer is applied to soils, the phosphate concentration is very high and the pH is quite low in the immediate vicinity of the fertilizer granule. In this study, the release of potassium (K) by 1 M NH4H2PO4 solution at pH 4.0 from three Chinese soils, Oxisol, Alfisol and Entisol, was investigated. The results showed that NH4H2PO4 promoted K release from these soils. The NH4H2PO4-induced K release obeyed the zero-order kinetics; the release-rate coefficients from these soils at 25 °C ranged from 72 to 170 μg K kg−1 h−1, much higher than observed (4–37 μg kg−1 h−1) in 1 M NH4Cl at pH 4.0. The combined effect of phosphate and proton on the alteration of K-bearing minerals was evidently the major mechanism of the NH4H2PO4-induced K release from the soils. The data indicated that the application of NH4H2PO4 fertilizer may enhance the rate of K supply in soils and lead to the conversion of some of N and P in the fertilizer to a slowly available form in soils because of the formation of a crystalline reaction product, ammonium taranakite. Key words: Potassium dynamics, phosphate application, ammonium taranakite

Pseudo-Homogenous Kinetics Model for the Synthesis of Dimethyl Carbonate from Urea and Methanol with Heterogeneous Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 481-486
Author(s):  
Wen Bo Zhao ◽  
Ning Zhao ◽  
Fu Kui Xiao ◽  
Wei Wei
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Dimethyl Carbonate ◽  
Side Reaction ◽  
Order Reaction ◽  
Zero Order ◽  
Kinetics Model ◽  
First Order ◽  
Zero Order Reaction ◽  
Kinetics Of

The synthesis of dimethyl carbonate (DMC) from urea and methanol includes two main reactions: one amino of urea is substituted by methoxy to produce the intermediate methyl carbamate (MC) which further converts to DMC via reaction with methanol again. In a stainless steel autoclave, the kinetics of these reactions was separately investigated without catalyst and with Zn-containing catalyst. Without catalyst, for the first reaction, the reaction kinetics can be described as first order with respect to the concentrations of methanol and methyl carbamate (MC), respectively. For the second reaction, the results exhibit characteristics of zero-order reaction. Over Zn-containing catalyst, the first reaction is neglected in the kinetics model since its rate is much faster than second reaction. After the optimization of reaction condition, the macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model, in which a side reaction of DMC synthesis is incorporated since it decreases the yield of DMC drastically at high temperature. The activation energy of the reaction from MC to DMC is 104 KJ/mol while that of the side reaction of DMC is 135 KJ/mol.

Hydrogenation Kinetics of N-Ethylcarbaozle as a Heteroaromatic Liquid Organic Hydrogen Carrier

2014 ◽  
Vol 953-954 ◽  
pp. 981-984 ◽  
Author(s):  
Ming Yang ◽  
Yuan Dong ◽  
Han Song Cheng
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Hydrogen Pressure ◽  
Reaction Rate ◽  
Hydrogenation Reaction ◽  
First Order ◽  
First Order Kinetics ◽  
Hydrogenation Kinetics ◽  
Hydrogen Carrier ◽  
Kinetics Of

The catalytic hydrogenation kinetics of N-ethylcarbazole over 5 wt% Ru/Al2O3 was investigated at various temperatures. The results shows that the hydrogenation reaction was exothermic and high temperature is unfavorable for the reaction rate. Fully hydrogenation was achieved within 1 hour under the best reaction temperature of 170 °C. The kinetics of N-ethylcarbazole follows the first-order kinetics in terms of the reactant concentration but independent of hydrogen pressure, which was maintained as a constant in the reaction process. The apparent activation energy of N-ethylcarbazole hydrogenation reaction at 150-180 °C was found to be 71.2 kJ/mol.

A Kinetic Study of Acid Corrosion of Cadmium

CORROSION ◽  
1958 ◽  
Vol 14 (1) ◽  
pp. 31-32
Author(s):  
HENRY WEAVER ◽  
CECIL C. LYNCH
Keyword(s):  
Activation Energy ◽  
Dilute Hydrochloric Acid ◽  
Reaction Rate ◽  
Acid Corrosion ◽  
Rotational Velocity ◽  
Cylindrical Sample ◽  
Zero Order ◽  
Cadmium Metal ◽  
Kinetics Of ◽  
Rate Controlling Step

Abstract The kinetics of the reaction of dilute hydrochloric acid with cadmium metal, molded, electroplated on brass, and dipped on brass, have been investigated by means of calibrated conductance measurements. The effect of annealing molded cadmium samples was to reduce the corrosion rate. Changing the speed of spinning the cylindrical sample increased the rate with increase in rotational velocity, up to a constant value at high velocities. The reaction rate at three acid concentrations and at three temperatures were determined. The activation energy is small, between one and two kilocalories per mole of cadmium reacting. In all cases the reaction was zero order over 90 percent of the reaction process. The rate controlling step has been estimated as that of diffusion through the layer surrounding the cadmium surface. 3.8.4

The Vulcanization of Elastomers. 16. The Vulcanization of Natural Rubber with Sulfur in the Presence of Dithiocarbamates (I)

1958 ◽  
Vol 31 (2) ◽  
pp. 301-314 ◽  
Author(s):  
Walter Scheele ◽  
Klaus Birghan
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Zero Order ◽  
Molar Ratio ◽  
Temperature Function ◽  
Final Value ◽  
Rate Versus ◽  
Zinc Diethyldithiocarbamate ◽  
Kinetics Of ◽  
Limiting Value

Abstract The kinetics of vulcanization of natural rubber with sulfur (initial concentration: 1 mole S8 in 10 kilograms of mixture) was investigated in the presence of varying amounts of zinc diethyldithiocarbamate (ZnDEDC). The following results were obtained. 1. At all temperatures and, depending upon the dithiocarbamate content of the mixture, over practically the entire, or at least the greater, extent of vulcanization, sulfur decrease is a zero order process. 2. The rate of sulfur decrease is, as long as it proceeds according to zero order, independent of the molar ratio S8:ZnDEDC. From the slope of the log rate versus 1/T plot is derived an activation energy of 29.2 kcal. 3. During vulcanization the dithiocarbamate content declines as long as the sulfur decrease follows the zero order. With decreasing starting content of dithiocarbamate, the stock finally uses up all the zinc dithiocarbamate during vulcanization. In other cases, a constant limiting value of dithiocarbamate decrease appears. 4. When zinc dithiocarbamate and zinc oxide are both present, sulfur decrease again takes place according to zero order. Under these conditions the process will use up less dithiocarbamate and shortly after the onset of vulcanization a constant final value of dithiocarbamate appears. 5. After the initial lag, crosslinking, measured by reciprocal equilibrium swell in benzene, proceeds according to zero order over the major extent of vulcanization. The temperature function of relative rates of crosslinking furnishes an activation energy similar to that for the rate of sulfur decrease. 6. Reciprocal equilibrium swell deviates from zero order time dependence as soon as the dithiocarbamate decrease reaches its final value, and the sulfur decrease also experiences a considerable lag. 7. It is shown that the limiting value of equilibrium swell increases as the starting content of dithiocarbamate decreases and also that reversion sets in at higher temperatures. When the molar ratio of mixing S8:ZnDEDC amounts to 1 or to 0.5, the limiting value of the swelling index is reached independent of temperature, i.e., the degrees of crosslinking are the same for these two ratios. The investigations will be continued.

Vulcanization of Elastomers. 28. Vulcanization of Natural and Synthetic Rubbers with Sulfur in the Absence of Accelerators. I

1960 ◽  
Vol 33 (4) ◽  
pp. 1051-1061
Author(s):  
Elisabeth Echte ◽  
Walter Scheele ◽  
Sigrun Sonnenberg
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Zero Order ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Sulfur Solubility ◽  
Temperature Relation ◽  
Sulfur Vulcanization ◽  
Rate Relationship ◽  
Kinetics Of

Abstract The decrease of sulfur concentration in the reaction of sulfur with natural rubber was studied. The following was found : 1. Sulfur decrease follows the 0.6th order law independent of temperature as long as the sulfur is dissolved in the gum (temperature!). From the rate-temperature relation, an activation energy of 35 kcal/mole is calculated. 2. In an investigation of the kinetics of sulfur concentration at constant temperature but increasing starting concentration, the following two cases can be differentiated : a) As long as the sulfur is soluble in the gum, sulfur decrease still follows the 0.6th order, possibly due to autocatalysis ; the linear relationship between starting rate and starting concentration shows that the process is 1st order with respect to the concentration; this may be the consequence of a thermal, rate determining cleavage of the S8 ring. b) As the sulfur at higher concentration is only incompletely soluble in the gum, conversion curves with points of inflection are found ; this becomes more pronounced at higher concentration. At the start of the reaction one finds an autocatalytic sulfur decrease basically of zero order; in the latter part of the reaction after passing the point of inflection a 0.6th order is observed, as in the range of complete sulfur solubility. 3. A discrepancy between the time law and the concentration-rate relationship is found in pure as well as accelerated sulfur vulcanization ; these conditions are compared and discussed.

scholarly journals Kinetic Study of Gas Formation in Styrofoam Pyrolysis Process

2021 ◽  
Vol 4 (2) ◽  
pp. 135-140
Author(s):  
I Dewe Ketut Anom
Keyword(s):  
Activation Energy ◽  
Constant Temperature ◽  
Natural Zeolite ◽  
Zeolite Catalyst ◽  
Arrhenius Equation ◽  
Zero Order ◽  
Pyrolysis Process ◽  
Energy Value ◽  
Gas Formation ◽  
Kinetics Of

This research aims to study the reaction kinetics of gas formation in the pyrolysis of styrofoam waste. Pyrolysis of styrofoam waste without a catalyst takes place at a constant temperature of 180°C. In contrast, the pyrolysis of styrofoam waste by adding a zeolite catalyst took place at a constant temperature of 170°C. The amount of styrofoam waste used in this research sample is 200 grams, and the natural zeolite catalyst is 5 grams. Pyrolysis of styrofoam waste without using a catalyst form a gas at a constant temperature of 180°C, the kinetics of the reaction takes place on the zero-order. This result follows the Arrhenius equation K = Ae10617/RT with an activation energy value (Ea) of 1.27x103 kJ.mol-1. Pyrolysis of styrofoam waste by adding a zeolite catalyst to gas formation at a constant temperature of 170°C also takes place on the zero-order. The equation follows Arrhenius K= Ae4711,5/RT and the activation energy value (Ea) is 5.66x102 kJ.mol-1.

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