Pyrolysis of methylcyclohexane

1987 ◽  
Vol 52 (6) ◽  
pp. 1527-1544 ◽  
Author(s):  
Ulrika Králíková ◽  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Order Reaction ◽  
The Other ◽  
First Order ◽  
Consecutive Reactions ◽  
Secondary Reactions ◽  
Kinetics Of

The kinetics of pyrolysis of methylcyclohexane was investigated from the viewpoint of coke formation in a steel tubular reactor (S/V = 6·65 cm-1) at 0·1 MPa, 700 to 820 °C and residence time 0·01 to 0·24 s. Decomposition of methylcyclohexane proceeds as a first order reaction with a frequency factor 6·31 . 1015 s-1 and activation energy 251·2 kJ mol-1. The course of secondary reactions associated with the formation of coke is discussed. Investigation of coke formation showed a greater tendency of methylcyclohexane to coking in comparison with heptane. A prominent role plays the course of dehydrogenation of cycloalkane radicals up to aromates, this being reflected by the overall conversion of methylcyclohexane, and, on the other hand the thus formed aromates enter the consecutive reactions leading to coke.

Pyrolysis of Hexadecane

1997 ◽  
Vol 62 (7) ◽  
pp. 1057-1069 ◽  
Author(s):  
Elena Barteková ◽  
Martin Bajus
Keyword(s):  
Hydrogen Transfer ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Mass Ratio ◽  
Pyrolysis Products ◽  
Alkyl Radicals ◽  
Secondary Reactions ◽  
Increasing Temperature ◽  
Kinetics Of

The kinetics of thermal decomposition of hexadecane was studied in a flow tubular reactor from stainless steel. The experiments were performed in the temperature range of 700 to 780 °C for the mass ratio of steam to hydrocarbon 3 : 1. The hexadecane pyrolysis took place according to the first-order reaction with a frequency factor of 3.5 . 109 s-1 and an activation energy of 162 kJ mol-1. In the pyrolysis products there were above all 1-alkenes. From alkanes, methane and ethane and less propane were formed in a higher degree. The prevailing compounds are ethene and propene whose amount increases with increasing temperature and residence time. The content of 1-alkenes higher than 1-pentene decreases with increasing conversion which gives evidence of their decomposition owing to their lower stability in comparison with the lighter 1-alkenes. The formation of dienes (1,3-butadiene and propadiene) and benzene also confirmed the course of secondary reactions. The observed higher formation of hydrogen results from the reaction of steam with coke deposited on the walls of the reactor or with hydrocarbon radicals. The evidence of the coke formation is given also by the presence of carbon oxides whose amount grew with the pyrolysis severity. The high content of 1-hexene in comparison with the other higher 1-alkenes is probably caused by the isomerization of alkyl radicals by 1,5-hydrogen transfer.

scholarly journals The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate

2000 ◽  
Vol 65 (12) ◽  
pp. 857-866
Author(s):  
Mladjen Micevic ◽  
Slobodan Petrovic
Keyword(s):  
Kinetic Data ◽  
Reaction Rate ◽  
Frequency Factor ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Activation Entropy ◽  
Second Order Reaction ◽  
Third Order ◽  
First Order ◽  
Kinetics Of

The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate (soman) was examined with a series of alkoxides and in corresponding alcohols: methanol, ethanol, 1-propanol, 2-propanol, 2-methoxyethanol and 2-ethoxyethanol. Soman reacts with the used alkoxides in a second order reaction, first order in each reactant. The kinetics of the reaction between 1,2,2-trimethylpropyl-methylfluorophosphonate and ethanol in the presence of diethylenetriamine was also examined. A third order reaction rate constant was calculated, first order in each reactant. The activation energy, frequency factor and activation entropy were determined on the basis of the kinetic data.

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.

scholarly journals INFLUENCE OF TEMPERATURE AND PH ON THE DECOMPOSITION KINETICS OF PERACETIC ACID IN AQUEOUS SOLUTIONS

2014 ◽  
Vol 44 (3) ◽  
pp. 195-201
Author(s):  
L. KUNIGK ◽  
S. P. GALIZIA ◽  
R.T. K. SHIKISHIMA ◽  
R. GEDRAITE ◽  
C. H. JURKIEWICZ
Keyword(s):  
Activation Energy ◽  
Aqueous Solutions ◽  
Peracetic Acid ◽  
Food Industry ◽  
Decomposition Kinetics ◽  
Order Reaction ◽  
Influence Of Temperature ◽  
First Order ◽  
All Solutions ◽  
Kinetics Of

Peracetic acid (PAA) is a strong oxidant used by the food industry as a sanitizer, in medical area as a disinfectant and by the textiles and paper industries as a bleacher. Its decomposition rate is an important parameter in these applications. The main purpose of this paper is to study the decomposition kinetics of PAA between 25 and 45 °C in solutions with pH 3.11, 5.0 and 7.0. The decomposition of PAA is a first-order reaction for all solutions and temperatures studied. The rate constants were between 2.08·10-3 and 9.44·10-3 h-1 (pH 3.11), between 2.61·10-3 and 16.69·10-3 h-1 (pH 5.0) and between 7.50·10-3 and 47.63·10-3 h-1 (pH 7.0). The activation energy of PAA decomposition in aqueous solutions are 58.36 and 72.89 kJ·mol-1 when pH was 3.11 and 5.0, respectively.

Kinetics of Methylation of Methyl 5-Deoxy-α/β-D-xylofuranosides

2004 ◽  
Vol 69 (10) ◽  
pp. 1877-1888
Author(s):  
Mária Oščendová ◽  
Jitka Moravcová
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Reaction Rate ◽  
Steric Effect ◽  
Order Reaction ◽  
Half Time ◽  
First Order ◽  
Consecutive Reactions ◽  
Kinetics Of

The kinetics of methylation of methyl 5-deoxy-α-D-xylofuranoside (1), methyl 5-deoxy-β-D-xylofuranoside (2) and their partly methylated derivatives with methyl iodide in the presence of sodium hydroxide in acetonitrile was studied. The reaction rate was independent of the base concentration during the first half-time only and the methylation proceeded as a first-order reaction. The rate constants of all side and consecutive reactions were calculated and the influence of both polar and steric effect is discussed. The methylation of 1 was highly regioselective giving almost exclusively 5-deoxy-2-O-methyl-α-D-xylofuranoside.

scholarly journals Kissinger Method in Kinetics of Materials: Things to Beware and Be Aware of

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2813 ◽  
Author(s):  
Sergey Vyazovkin
Keyword(s):  
Activation Energy ◽  
Isoconversional Methods ◽  
Single Step ◽  
Order Reaction ◽  
Kissinger Method ◽  
Scanning Calorimetry ◽  
First Order ◽  
Kinetics Of ◽  
Final Equation ◽  
Derivative Thermogravimetry

The Kissinger method is an overwhelmingly popular way of estimating the activation energy of thermally stimulated processes studied by differential scanning calorimetry (DSC), differential thermal analysis (DTA), and derivative thermogravimetry (DTG). The simplicity of its use is offset considerably by the number of problems that result from underlying assumptions. The assumption of a first-order reaction introduces a certain evaluation error that may become very large when applying temperature programs other than linear heating. The assumption of heating is embedded in the final equation that makes the method inapplicable to any data obtained on cooling. The method yields a single activation energy in agreement with the assumption of single-step kinetics that creates a problem with the majority of applications. This is illustrated by applying the Kissinger method to some chemical reactions, crystallization, glass transition, and melting. In the cases when the isoconversional activation energy varies significantly, the Kissinger plots tend to be almost perfectly linear that means the method fails to detect the inherent complexity of the processes. It is stressed that the Kissinger method is never the best choice when one is looking for insights into the processes kinetics. Comparably simple isoconversional methods offer an insightful alternative.

THE THERMAL DECOMPOSITION OF STYRENE–BUTADIENE POPCORN POLYMER

1950 ◽  
Vol 28b (1) ◽  
pp. 5-16
Author(s):  
C. A. Winkler ◽  
J. Halpern
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Linear Relation ◽  
Frequency Factor ◽  
Thermal Reaction ◽  
Cross Linking ◽  
First Order ◽  
Bond Scission ◽  
Styrene Butadiene ◽  
Kinetics Of

At temperatures of the order of 250 °C., popcorn polymer undergoes decomposition to soluble polymer. The reaction is catalyzed by peroxides present in the popcorn when the latter is formed. These peroxides may be removed by extracting the polymer with benzene. The kinetics of both the catalyzed and purely thermal solubilization reactions were investigated. The rates of both reactions are first order, the catalyzed degradation having a higher activation energy and a higher frequency factor. The rate of the thermal reaction decreases and its activation energy increases with increasing butadiene content of the polymer. A linear relation between the activation energy and the log of the frequency factor, for the decomposition of popcorn polymers of different butadiene contents, was observed. The results indicate that the rate of solubilization is determined by the activation energy of the bond scission process, and is independent of the degree of cross-linking of the polymer.

An Experimental Study of the Coking Process

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Somayeh Ebrahimi ◽  
Jafarsadegh Moghaddas
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Nitrogen Atmosphere ◽  
Fuel Oil ◽  
Effective Parameters ◽  
Pyrolysis Kinetics ◽  
Exponential Factor ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

The coking process includes two dynamic and isothermal steps. In this process, some factors control the coke formation kinetics. In this research, effects of some important and effective parameters of feed on the quality of petroleum coke were studied. Two hydrocarbon residue feeds; Cracked Fuel Oil (CFO) and Styrene Monomer Tar (SMTAR) were used at 500°C with atmospheric pressure of nitrogen used as an inert gas. Rate of weight loss and gas evolution from these feeds were considered by data of thermal analysis TG (thermogravimetry) and DTG (derivative thermogravimetry). Based on the results, CFO was assigned as the better feed. After selecting better feed, simultaneous thermogravimetry-differential analysis (TG-DTA) was used to study the pyrolysis kinetics of CFO. Samples were heated in a TG-DTA apparatus in nitrogen atmosphere at a temperature range of 37-600°C. The activation energy (Ea) and pre-exponential factor (A) were calculated from the experimental results by using a three stage Arrhenius-type kinetic model and showed that CFO pyrolysis kinetics at temperature ranges 37-285, 320-450 and 467-600°C follows first, second and first order kinetics, respectively. Attentive to temperature increase and reaction progress, activation energy and pre-exponential factor indicated different values at each stage. Also, kinetics of the isothermal step of coke formation was studied during heating of CFO. Samples were reacted in a tube furnace at 450°C and with nitrogen atmosphere. The kinetics of coke formation for petroleum residue was followed by solvent extraction (insolubility in hexane (HI), toluene (TI)) and a development of TI approximate to apparent first order kinetics. The rate constant at this temperature was calculated and it was also observed that the coke formation had been started at a temperature below 450°C.

Thermal and kinetic behaviors of corn stover and polyethylene in catalytic co-pyrolysis

BioResources ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. 4102-4117
Author(s):  
Shaoqing Wang ◽  
Xiaona Lin ◽  
Zhihe Li ◽  
Weiming Yi ◽  
Xueyuan Bai
Keyword(s):  
Activation Energy ◽  
Corn Stover ◽  
Compensation Effect ◽  
Kinetic Studies ◽  
Order Reaction ◽  
Kinetic Compensation Effect ◽  
Exponential Factor ◽  
First Order ◽  
Thermogravimetric Data ◽  
Kinetics Of

Thermal decomposition characteristics and kinetics of high-density polyethylene (HDPE), corn stover (CS), and their blended mixture (1:1 w/w ratio) during non-catalytic and catalytic co-pyrolysis were studied via thermogravimetric analysis (TGA). The results indicated synergetic interactions between the biomass and the plastics during co-pyrolysis as measured by weight loss (ΔW); this effect was attributed to radical interactions during co-pyrolysis. The pyrolysis catalysts with higher nickel loadings (5%, 10%, and 15%) appreciably diminished the solid residue. Kinetic studies indicated that the pyrolysis was a first-order reaction based on the fitted thermogravimetric data. The activation energy (E) and pre-exponential factor (A) ranged between 26.13 kJ/mol to 392.67 kJ/mol and between 156.24 min-1 to 9.19 x 1023 min-1, respectively. There was a kinetic compensation effect (KCE) observed among the two kinetic parameters. The activation energy (E) decreased for each pyrolysis stage with the presence of a catalyst. The results indicated that catalytic co-pyrolysis could provide great potential for reducing the pyrolysis energy input.

Vulcanization Kinetics of Natural Rubber Coagulated by Microorganisms with Use of a Vulcameter

2010 ◽  
Vol 160-162 ◽  
pp. 1181-1186 ◽  
Author(s):  
Zhi Feng Wang ◽  
Si Dong Li ◽  
Xiao Dong She
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Rate Constants ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Second Stage ◽  
End Stage ◽  
Two Stages ◽  
Kinetics Of

Kinetics of vulcanization of natural rubber coagulated by microorganisms (NR-m) was studied with the use of a vulcameter. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a), and the rate constant k1/a of NR-m are greater than that of NR-a. Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction. The rate constants k2 of NR-m in the first stage are greater than that of NR-a at the same temperature, and so are the activation energy E2. The second stage (end stage of the curing period) does not follow first-order reaction, and the calculated reaction order n of NR-m is in the range of 0.82-0.85, and that of NR-a is in the range of 0.64-0.72. The rate constants k3 of the second stage for NR -m are greater than that of NR-a at the same temperature, and so is the activation energy E3.

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