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ORGANIC CHEMISTRY
DOI - 10.32 743/UniChem.2024.118.4.17181 ACETYLENE CATALYTIC ACETYLATION OF VINYL ACETATE IN THE LABORATORY
Bekhruzjon Omanov
Doctor of Philosophy of Technical Sciences, Associate Professor, Navoi State Pedagogical Institute, Republic of Uzbekistan, Navoi E-mail: omanovbekhruzjon@gmail. com
АЦЕТИЛЕН-КАТАЛИТИЧЕСКОЕ АЦЕТИЛИРОВАНИЕ ВИНИЛАЦЕТАТА
В ЛАБОРАТОРИИ
Оманов Бехрузжон Шухрат угли
д-р техн. наук, доцент, Навоийский государственный педагогический институт, Республика Узбекистан, г. Навои
ABSTRACT
Among the oxygen compounds produced in the chemical and basic organic synthesis industry, vinyl ethers occupy one of the first places. Vinyl acetate is of particular importance. Aqueous solutions of Zn(CH3COO)2, Cd(CH3COO)2, ZrO(NO3)2 salts were used for sol-gel synthesis of nano-sized particles. Qualitative analysis was carried out by the method of "witnesses", quantitative analysis was carried out by the method of internal normalization. Zinc acetate, zinc acetate and cadmium acetate and zinc acetate, cadmium acetate and zirconium oxynitrate mixture catalysts were obtained from acetylene and acetic acid. Synthesis products were analyzed by gas-liquid chromatography with a flame ionization detector under the following normal conditions. Reactors of processes for obtaining vinyl acetate by catalytic acetylation of acetylene were mathematically modeled.
АННОТАЦИЯ
Среди кислородных соединений, получаемых в промышленности химического и основного органического синтеза, виниловые эфиры занимают одно из первых мест. Винилацетат имеет особое значение. Водные растворы солей Zn(CH3COO)2, Cd(CH3COO)2, ZrO(NO3)2 использовали для золь-гель синтеза наноразмерных частиц. Качественный анализ проводился методом «свидетелей», количественный анализ - методом внутренней нормализации. Катализаторы из смеси ацетата цинка, ацетата цинка и ацетата кадмия и смеси ацетата цинка, ацетата кадмия и оксинитрата циркония получали из ацетилена и уксусной кислоты. Продукты синтеза анализировали методом газожидкостной хроматографии с пламенно-ионизационным детектором при следующих нормальных условиях. Математически смоделированы реакторы процессов получения винилацетата каталитическим ацетилирова-нием ацетилена.
Keywords: acetylene, catalyst, acetic acid, vinyl acetate, sol-gel technology.
Ключевые слова: ацетилен, катализатор, уксусная кислота, винилацетат, золь-гель технология.
Introduction
Among the oxygen compounds produced in the chemical and basic organic synthesis industry, vinyl ethers take one of the first places. Vinyl acetate is of particular importance. Vinyl acetate was studied since 1909 and was first obtained and isolated in 1912 by the German chemist F. Klatte.
C2H2+2CH3COOH^ CH3CH(OCOCH3)2
C2H2+CH3COOH ^ CH2=CHOCOCH3
Vinyl acetate is one of the most important monomers, the production of which is growing rapidly all over the world. The value of vinyl acetate has increased dramatically with the development of the plastics industry, as they polymerize to form resins with good optical and mechanical properties. Among the polymers synthesized from vinyl acetate, polyvinyl alcohol, polyvinyl acetate and polyvinyl acetals, it is the most widely used. Polyvinyl acetate has high viscosity properties and is used for adhesives, water-soluble latex paints, fabric sizing, and other.
Библиографическое описание: Omanov B.Sh. ACETYLENE CATALYTIC ACETYLATION OF VINYL ACETATE IN THE LABORATORY // Universum: химия и биология : электрон. научн. журн. 2024. 4(118). URL:
https://7universum.com/ru/nature/archive/item/17181
Experimental part
The most effective method for obtaining mesoporous catalysts is the 'sol-gel' technology, which allows controlling the particle size, surface area, and pore structure of the catalyst at any stage.
Aqueous solutions of Zn(CH3COO)2, Cd(CH3COO)2, ZrO(NO3)2 salts were used for sol-gel synthesis
of nano-sized particles. A nanocatalyst with the following structure was selected for catalytic acetylation of acetylene.
After that, we studied the effect of the mass ratio of the catalyst active components on the catalyst activity in the catalytic acetylation reaction of acetylene. The obtained results are presented in Table 1.
Table 1.
The influence of the mass ratio of catalyst active components on catalyst activity in the catalytic acetylation
reaction of acetylene
№ Catalyst com osition Catalyst performance, g/l-cat-h
Zn(CH3COO)2 Cd(CH3COO)2 Zn(CH3COO)2 mass, % Cd(CH3COO)2 mass, % ZrO(NO3)2 mass, %
1 1 1 25,6 2,8 - 205
2 9 1 23,7 2,6 1,0 328
3 9 1 21,8 2,4 2,0 316
4 3 1 20,0 6,7 - 230
5 3 1 18,6 6,6 1,0 363
6 3 1 17,5 5,8 2,0 347
7 1 1 15,0 15,0 - 315
8 1 1 13,5 13,5 0:1 440
9 1:1 11,5 11,5 1,0 480
10 1:1 11,0 11,0 2,0 430
11 1:1 10,0 10,0 5,0 418
As it can be seen from Table 2, the influence ratio Zn(CH3COO)2:Cd(CH3COO)2:ZrO(NO3)2=11.5:11.5:1.0
of catalyst active components mass ratios on catalyst ac- (in mass percent) the productivity of the catalyst will
tivity in the catalytic acetylation reaction of acetylene have the highest value.
j
1 - needle valve; 2 - rheometer; 3 - absorbent with hydroxylamine; 4 - drying column; 5 - evaporator; 6 - bathroom; 7 - reactor; 8 - thermowell; 9 - transformer; 10 - voltmeter; 11 - reactor temperature control unit; 12 - air cooler; 13 - water-cooled refrigerator; 14 - xylene traps; 15 - exhaust gas line
Figure 1. Scheme of production of vinyl acetate in the laboratory
A metal reactor (7) with a diameter of 40 mm and a height of 380 mm is equipped with a mesh-substrate on the bottom. The upper flange cover is equipped with two fittings: a steam-gas mixture (acetylene saturated with acetic acid vapors) and a thermowell (8). The lower flange-bottom part is equipped with fittings for removing reaction products.
TEN-06 heating elements with a total power of 3.6 kV are evenly distributed around the reactor vessel (7), which are connected to the 220 V network through a control transformer (9). It is not allowed to supply more than 220 V to prevent overheating.
The surface of the reactor is insulated and wrapped to conserve heat and maintain a stable temperature. The temperature in the reactor was measured by a THC thermocouple with signals output to the temperature control unit (11), the readings were recorded on the KSP potentiometer or indicating device.
The acetylene used from the cylinder is purified from acetone in an absorber with 10% hydroxylamine (3), and the acetylene is dried in a drying column with calcium chloride (4).
To carry out the synthesis, a certain amount of catalyst is loaded into the reactor. The catalyst is heated in a stream of nitrogen. When the temperature reached 180 °C, the valve in the mixed gas line (1') of workshop No. 007 was opened (or acetylene concentrate from the cylinder), and the valve in the nitrogen line (1) was closed. For saturation with acetic acid, the gas was
passed through an acetic acid evaporator placed in a water bath with a temperature of -95-100 °C. Then the gas saturated with acetic acid entered the reactor, where the acetylation reaction took place on the catalyst at a temperature of 180-210°C. During the reaction, the parameters of the technological mode, temperature conditions, and the flow rate of the delivered components were measured.
The gaseous reaction products were cooled first in an air cooler (12) and then in a water-cooled refrigerator (Liebig) (13). Condensate and vinyl acetate vapors are absorbed in absorbers with xylene (14) placed in an ice bath (3-8°C). The reaction products obtained with the collected xylene were chromatographically analyzed for their constituents. Inlet and outlet gases were periodically analyzed by gas chromatography.
Discussion part
Synthesis products were analyzed by gas-liquid chromatography with a flame ionization detector under the following normal conditions: 15% Lestosil in Svetochrom-545 with a stationary liquid phase particle size of 0.250-0.315 nm, a glass with a size of 2x0.004 m column, column temperature 100°C, carrier gas-nitrogen flow consumption 30 ml/min.
As a result of the conducted research, the following optimal condition of the analysis was chosen.
Table 2.
Chromatographic optimal conditions of the products of the catalytic acetylation reaction of acetylene
№ Kattaliklar Qiymati
1 Column length, m 1.5-2
2 Column diameter, mm, (thermostat temperature, 0C) 4
3 Column thermostat temperature, 0C 95-100
4 Evaporator temperature, 0C 180
5 Amount of stationary liquid phase, % 15
6 Carrier gas velocity, ml/min 30
7 Analysis duration, min 5-10
Qualitative analysis was carried out by the method of 'witnesses,' quantitative analysis was carried out by the method of internal normalization. Chromatograms obtained from acetylene and acetic acid on zinc acetate,
zinc acetate and cadmium acetate and zinc acetate, cadmium acetate and zirconium oxynitrate mixture catalysts are presented in Figures 2, 3 and 4 below.
1-acetylene; 2-acetaldehyde; 3-acetone; 4-vinylacetate; 5-croton aldehyde; 6-acetic acid; 7-ethylenediacetate Figure 2. Chromatogram of crude vinyl acetate obtained on ZnO/ ceramsite catalyst
1-acetylene; 2-acetaldehyde; 3-acetone; 4-vinylacetate; 5-croton aldehyde; 6-acetic acid; 7-ethylenediacetate Figure 3. Chromatogram of crude vinyl acetate obtained on ZnOCdO /ceramsite catalyst
1-acetylene; 2-acetaldehyde; 3-acetone; 4-vinylacetate; 5-croton aldehyde; 6-acetic acid; 7-ethylenediacetate Figure 4. Chromatogram of crude vinyl acetate obtained on ZnOCdOZrO2/ceramzite catalyst
As can be seen from the chromatograms, the amounts of acetylene, acetaldehyde, acetone, croton aldehyde, acetic acid, and ethylidene acetate adducts in ZnO-CdO-ZrO2/keramzite catalysts are less than those formed in ZnO/ceramzite and ZnO-CdO/keramzite catalysts.
Product yield in the synthesis of vinyl acetate from acetylene depends on 3 factors: process temperature, acetylene volumetric rate (x2), height of the catalyst layer. A series of preliminary experiments was conducted according to the plan of 23 fully factorial experiments. The complete factorial experiment design matrix and its results are presented in Table 3 below.
Table 3.
Plan-matrix of full factorial experiment and its results
Factor levels and change intervals
Level zero (x; = 0) 185 280 40
Replacement intervals (AXj) 25 50 10
Lower level (x; = -1) 160 230 30
High level (x; = +1) 210 330 50
Plan Xi X2 X3 Y
Tajribalar 1 - - - 20,5
2 + - - 28,3
3 - + - 26,8
4 + + - 34,6
5 - - + 26,4
6 + - + 44,2
7 - + + 52,7
8 + + + 70,5
As a result of processing the results of the experiment, the following polynomial was obtained: Y = 21 + 8x1 - 16x2 + 10x1x1.
To carry out analytical optimization of the model, if we consider the model as an incomplete quadratic equation and optimize it, we will have two linear equations:
dy
8
/dX1 =8 + l0*2 = 0-*2 = --=-0,8
dy
'/dx2 = 16 + 10Xi = 0 ^ x2 = - 16/io = -1,6
Then the optimized equation takes the following form:
YX2=0,8 = 21 + 8x1 - 16 • 0,8 + 10x1 • 0,8 = 8,2 + 16x1
Conclusion
Thermally stable, high activity, selectivity and productivity nanocatalysts for ZnOCdOZrO2/ceramzite reactions for catalytic acetylation of acetylene from local raw materials were created based on 'sol-gel' technology. Catalytic acetylation reactions of acetylene were thermodynamically justified. Reactors of processes for obtaining vinyl acetate by catalytic acetylation of acetylene were mathematically modeled.
References:
1. Tyomkin O.N., Abanto-Chavez X.Y., Hoang Kim Bong. 'Kinetic models of vinyl acetate synthesis on new generation zinc acetate catalysts' // Kinetics and Catalysis, 2000, No. 5, v. 41, PP. 701-718.
2. Hoang Huu Binh. Features of the formation and technology of zinc acetate catalysts for the synthesis of vinyl acetate // Dissertation of a candidate of chemical sciences: 05.17.04: Moscow, 2004. PP.-108.
3. Faizullaev N.I., Turobzhonov S.M. Buf fazada vinyl acetate catalyst synthesis // Tashkent State Technical University Khabarlari, 2014.-No. 2.-167-175.
4. Faizullaev N.I., Muradov K.M. Study of the reaction of catalytic vapor-phase synthesis of vinyl acetate on a supported catalyst. // Chemical industry, 2004.-Vol.81.- No.3.- PP.136-138.
5. Faizullaev N.I. Acetylene bufazada catalytic acetyllash. // Reports of the Academy of Sciences, 2002. No. 5. -PP. 47-50.
6. Oreski G., Ottersb'ock B., Omazic A., Degradation processes and mechanisms of encapsulants, in: Durability and Reliability of Polymers and Other Materials in Photovoltaic Modules, Elsevier, 2019, pp. 135-152.
7. Lange R.F., Luo Y., Polo R., Zahnd J., The lamination of (multi) crystalline and thin film based photovoltaic modules, Prog. Photovoltaics Res. Appl. 19 (2) (2011) 127-133.
8. Pern F., Czanderna A., Characterization of acetylene vinyl acetate (AVA) encapsulant: effects of thermal processing and weathering degradation on its discoloration, Sol. Energy Mater. Sol. Cell. 25 (1-2) (1992) 3-23.
9. Bekhruzjon Omanov, Normurot Fayzullaev, Mukhabbat Khatamova, Almagul Xalibekova, Madina Avezova//Opti-mizing Vinyl Acetate Production Process and Selecting of Appropriate Reactor Type//AIP Conference Proceedings 2789, 020008 (2023) https://doi.org/10.1063/5.0145637
10. Bekhruzjon Omanov, Normurot Fayzullaev, Mukhabbat Khatamova, Nigina Ruziqulova, Sardor Rustamov//Energy and Resource Saving Technology of Vinylacetate Production from Acetylene// AIP Conference Proceedings 2789, 020009 (2023) https://doi.org/10.1063/5.0145636
