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Citation: N.I. Fayzullayev SH.B Rakhmatov. Modeling of A Reactor Preparation Ethylene From Methane. Nano Tech Nano Sci Ind J.
141:130.
© 2005 Trade Science Inc.
1
MODELING OF A REACTOR PREPARATION ETHYLENE FROM
METHANE
N.I. Fayzullayev and SH.B. Rakhmatov
Samarkand State University Bukhara Medical Institution Uzbekistan
Corresponding author: Samarkand State University Bukhara Medical Institution Uzbekistan Tel: + 998933589082 E-
Mail: xurshiduzyandex.ru t-xurshidsamdu.uz
Received: February 29 2019 Accepted: March 12 2020 Published: March 20 2020
Introduction
Uzbekistan has vast reserves of oil and natural gas. Natural gas and oil are known to be reserves of non-renewable and
limited raw materials. The rational use of oil and gas will help develop the chemical industry at a higher level. Particular
attention is paid to the use of highly efficient low-waste economical environmentally friendly technologies and
environmental protection for the efficient use of oil and natural gas. Based on the foregoing one of the main challenges
facing the scientists of the world is the introduction of new methods of producing sync. Tactical materials important for the
national economy which can replace products imported on the basis of local raw materials and industrial waste and without
waste environmentally friendly high-quality and competitive. The development of new technologies At the same time the
only reasonable way to process natural gas is through oxygenation. This process occurs at one stage and at atmospheric
pressure. This process passes through ethane and ethane is dehydrated with ethylene production. Considering the whole
substance you can write the following sequence of reactions.
400CH4+259O2 → 90C2H6+70C2H4+64CO2+374H2O+16H2+16CO
514
0
800
C
H kJ/mol.
Experimental
The gaseous products of the reaction was analyzed using a “Gazokhrom3101” thermochemical detector using the following
thermostat: Thermostat temperature is 100°С transport gas air flow rate is 35 ml/min the length of the column filled with
activated carbon is 1 m internal diameter is 3 mm. Quantitative analysis was carried out by the absolute rating method. The
Abstract
In this study catalytic oxygenation of methane and the influence of various factors in the process of ethylene production were studied. Based on the
results obtained the optimal conditions and the structure of the catalyst were chosen : Mn2O3x ∙ Na2MoO4y ∙ ZrO2z. The process was
thermodynamically evaluated to obtain the most appropriate technology for extracting ethylene from methane and the effect of various
technological parameters on its main characteristics for mathematical modeling of the reactor was investigated.
Keywords: temperature bulk velocity adiabatic reactor contact time conversion diameter film thickness mass transfer.
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catalytic activity of more than 10 catalysts was tested for the reaction of methane oxygenation. As is known manganese-
based catalysts have high catalytic activity and selectivity in the process of ethylene oxidation with methane. Therefore we
learned that manganese-based catalysts are a promoter feature of various compounds. The results are shown in the TABLE
1below.
TABLE 1. Results of studying the promoting properties of various compounds in catalysts prepared from manganese.
Serial
No
Promoter Reactor
temperature ºC
Methane
conversion mol
Selectivity Efficiency of
ethylene
C2-hydrocarbons
ethylene
1 Na3PO4
700 146 100 580 85
750 247 100 634 158
800 388 939 700 273
2 Na2B4O7
700 156 657 487 76
750 232 550 681 158
800 356 377 761 271
3 Na2MoO4
700 113 100 647 112
750 280 100 701 198
800 430 100 765 329
4 Na2WO4
700 138 603 493 68
750 215 288 656 141
800 329 299 693 228
As can be seen from the TABLE 1 when Na2MoO 4 is added to the manganese catalyst the total conversion of methane is
43.0 at 800 ° С 32.9 of the efficiency ethylene and 76.5 ethylene selectivity. We then added d-metal compounds to
Mn2O3 ∙ Na2MoO4. The best results were obtained by adding a catalyst ZrO2. The results of the experiments are shown in
TABLE 2.
TABLE 2. The effect of the catalyst on methane activity in the oxidative condensation reaction.
Serial
No
Composition of
catalyst
Methane rotation level Selectivity
Common С2Н4-а
1 La 2O 3 422 286 678
2 PbO 2 464 297 640
3 KCl 409 286 700
4 KBr 371 212 571
5 ZrO 2 526 428 814
6 BeO 482 346 718
The introduction of the ZrO 2 catalyst had a positive effect on its activation. When added ZrO2 catalyst the efficiency of
ethylene increased from 32.9 to 42.8 and the selectivity to ethylene from 76.5 to 81.4 respectively. Further experiments
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Mn2O3 x∙ Na2MoO4 y ZrO2 z with the participation of an optimal catalyst were carried out. The conversion of methane
depends on the C2-hydrocarbon process depends on the catalytic composition used but also depends on the reaction
conditions temperature methane air specific bulk velocity. Thus we learned the effect of various factors on the reaction
rate. The bulk velocity was investigated at a temperature of 800°C and a ratio of CH4: air1: 2. The change in bulk velocity
was achieved by changing the size of the catalyst which must be applied to the reactor. The first methane-air mixture was
sent continuously. The results are shown in TABLE 3.
TABLE 3. Effect of bulk velocity on methane oxygenation.
S.No Magnitude of bulk velocity h
-1
Catalyst volume ml Conversion rate S
General to С2Н4
1. 600 100 685 286 418
2. 800 75 619 358 578
3. 1000 60 526 428 814
4. 1200 50 433 329 759
5. 1400 42 348 236 678
However it was noted that additional products are formed decomposition of ethylene. The optimal value of the bulk
velocity is 1000 h -1 the value of ethylene is 42.8 and the selectivity is 81.4. The effect of temperature on the methane
oxidation reaction was investigated at constant bulk velocity 1000 h-1 and methane: air1: 2 with the presence of a catalyst
of optimal composition with a range of 50°at intervals of 600-850°C. The results are shown in TABLE 4.
The temperature of methane has a significant effect on the oxidation reaction as shown in TABLE 4.
Production of ethylene starts at 600
°
C. The highest ethylene yield was observed at 800°C. Increasing the temperature from
the optimum temperature can degrade the process. Therefore the ethylene content and selectivity decrease.
TABLE 4.The effect of temperature on the methane oxygenation reaction.
S.No Temperature ºC Methane conversion mol Selectivity
General С2Н4 а
1. 600 150 следы -
2. 700 364 234 643
3. 750 456 332 728
4. 800 526 428 814
5. 850 580 365 630
The effect of methane: air with temperatures of 800°C and a bulk velocity of 1000 h
-1
. The results are shown in TABLE 5.
The results of the TABLE 5 show that when the amount of air in the compound increases methane conversion increases
ethylene efficiency and selectivity decrease.
TABLE 5. Results of studying the effect of methane-air ratio for methane oxygenation. T750ОС Vcat6 ml.
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S.No Methane : air Methane conversion rate Selectivity
General to С2Н4
1. 3:1 250 62 248
2. 2:1 324 125 386
3. 1:1 458 236 515
4. 1:2 526 428 814
5. 1:3 608 305 502
To study the kinetic regularities of the methane oxygenation reaction the effect of methane and oxygen partial pressure on
the rate of production of ethylene at a temperature of 700 ÷ 800°C and a bulk velocity 600 ÷ 1200 h-1. In studying the effect
of the partial pressure of the reactants on the process flow laws changed the partial pressure of the gas and left the latter
unchanged. In order not to change the linear rate the required amount of argon gas was sent to the reaction zone. The catalyst
size was adapted to the specific velocity test conditions for permanent storage.
The Results of the Experiment and their Discussion.
Thermodynamic evaluation of the process and mathematical modeling of the reactor which is the core of the technological
process plays an important role in creating development technologies.
Thermodynamic analysis of the methane oxygenation reaction:
Thermodynamic parameters of the reaction calculated on the basis of the values of heat and Gibbs energy are given in
TABLE 6.
TABLE 6. Calculated values of heat and Gibbs energy of the reaction.
S.No Reaction
0
298
H kJ/mol
0
G J/mol · K
1 4CH 4+O 2 → 2C 2H 6+2H 2O -1766 -197296
2 2C 2H 6+O 2 → 2C 2H 4+2H 2O -1047 -363242
3 2CH 4+O 2 → C 2H 4+2H 2O -281314 -28006
4 C 2H 4+2O 2 → 2CO+2H 2O -756162 -937574
5 CH 4+2O 2 → CO 2+2H 2O -801724 -1006544
6 C 2H 4+3O 2 → 2CO 2+2H 2O -1321716 -1286186
7 CH 4+15O 2 → CO+2H 2O -518738 -609026
The adiabatic heating of the gas mixture is an important characteristic of the reactor. The adiabatic heating of gases for
different values of the methane-oxygen ratio based on the heat balance of the catalyst bed was calculated using the formula:
Тla y e r
Т
Т
р
g
dT С С e n t e r С e x i t enter C Wenter
0
i
Tlayer
i
Tlayer
i i
Wenter H Wenter H
The calculation results are shown in FIG. 1 below.
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FIG. 1. Relationship between the ratio of CH4:O2 and adiabatic heating on the source gas at p 0.1 MPa.
As can be seen from the figure methane content increases with adiabatic heating. As can be seen from the TABLE 7 when
Na2MoO4 is added to the manganese catalyst the total methane conversion is 43.0 at 800°C 32.9 of the efficiency of
ethylene and 76.5 selectivity ethylene. In terms of the ratio of methane-oxygen adiabatic heating to 575°C.
When the methane content in the source gases is 90 adiabatic heating decreases to 325°C. As it is known adiabatic type
reactors are often used for carrying out catalytic processes while the selectivity of the processes varies widely in the
temperature range. The advantage of these reactors is that 2-3 t/m
3
metal tanks at times are smaller and easy and cheap to
manufacture. Its disadvantage is that the reactions are carried out with a large thermal effect and the selectivity in the catalyst
layer is not the same to a high approximation methane oxygenation reaction may be carried out for 4-5-stage device. Under
these conditions this process is a good way to work.
TABLE 7. Parameters on the process are 5-step adiabatic reactor Mathematical modeling of methane oxygenation
reactor
P MPa CH4/O2
mol
TinputºС Тoutput ºС
s
2
O
K
4
CH
K
Yield
С2 С2Н4
01 5 800 1000 013 956 448 432 403
The ideal isothermal reactor model for reactor simulation was used:
The limiting stage of the process in the extraction of methane is the diffusion of oxygen on the outer surface. The oxygen
concentration and the partial pressure on the particle surface were in the following equation:
S
O
S
O
b
O
R C C
2 2 2
The
change in the total pressure on the layer is expressed by the Ergan equation:
2
2
2
U
f
L
P
.
The coefficient of hydraulic resistance for colored particles was determined by the following formula: 586 0
Re
4 38
f in
this
а р а л
4u
Re
э
. In the automatic mode all the heat dissipated during the process is used to heat the unwanted gas.
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Therefore the temperatures of the incoming and outgoing reactors are governed by the heat transfer equation 8 of the
catalyst.
As a result of studying the effect of mass transfer coefficients and other factors on the process parameters the main
indicators of the oxidizer of methane oxidizer were determined. The results are given in TABLE 8.
Thus methane oxygenation can be carried out in a single-stage adiabatic reactor in an auto thermal mode with an
effective diameter of catalyst particles under external diffusion conditions of 5.0 mm and a linear rate of 0.36 m/s. The
specific performance of the catalyst in the amount of C 2 hydrocarbons in the selected mode is 17280 kg C 2/m
3
∙ hour in
ethylene - 16253.5 kg/m3 ∙ hour. The thickness of the catalyst layer is 2.0 cm. Thus the capacity of the ethylene block is
16253.5 thousand units. kg/year the specific consumption of methane is 360 nm
3
/m
2
∙ hour.
TABLE 8. The Main Indicators of the Oxidizer of Methane Oxidizer were Determined.
TABLE 9. Construction characteristic of the methane oxygenation reactor ACM.
Main characteristics of the reactor Values
Capacity to С 2ethylene thousand kg/year 17280.01616253.50
Diameter of the device m 7.9
Specific methane consumption nm
3
/m
2
∙h 380
Oxygen concentration vol 16253.5
It should be noted that the power of methane oxygenation reactor can be increased by increasing the pressure in the system.
For example when the pressure increases to 0.5 MPa the specific power of the methane oxygenation reactor is about 33.800
Kg/year. The main construction characteristics of the reactor are shown in TABLE 9.
Parameter ACM
Characteristic particle size
d mm
5.0
Layer thickness h m/sec 2.0
Gas speed u m/sec 0.36
Conditional contact time sec 0.13
Conversion Х 95.6
Macrokinetic speed constant’s с
-1
36.7
Mass transfer coefficient с
-1
44.0
Kinetic speed constant’s k с
-1
220.0
Constant relation
/ k
5.0
Specific yield to С 2 g g/m
3
∙hour 1.9
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Conclusion
1. The catalytic oxygenation of methane and the influence of various factors on the process of ethylene production were
investigated.
2. The process was thermodynamically evaluated and a mathematical model of the reactor was modeled.
3. The basic parameters and design characteristics of the reactor RCM have been studied.
4. It was found that catalytic oxygenation of methane facilitates the process of producing ethylene in a 5-stage adatomic
reactor.
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