The way to obtain 1,1,2,2-tetrafluoroethane

 

(57) Abstract:

The invention relates to the chemical industry and can be used to obtain 1,1,2,2-Tetrafluoroethane (HFC 134), which is promising the ozone destruction. The method comprises the catalytic hydrogenation of tetrafluoroethylene at elevated temperature, preferably 160-250oC. the Process is carried out under adiabatic conditions. Source tetrafluoroethylene served on hydrogenation in a mixture with indifferent diluent, for example, HFC 134, and the molar ratio of refrigerant 134 - tetrafluoroethylene maintained within the range of 1 - 6. The molar ratio of hydrogen - tetrafluoroethylene support in the range of 0.9 to 1.2. As the catalyst used palladium deposited on an alpha alumina (corundum), preferably industrial catalyst APK-2. For igniting the catalyst of the initial gaseous mixture is pre-heated at least to the 50oC. the Method is characterized by a high yield of the desired product (99 %) and negligible formation of undesirable by-products 1,1,2-triptorelin and hydrogen fluoride, which is confirmed by laboratory experiments. 4 C.p. f-crystals, 1 table.

The invention relates to the organization of topicnum the halon.

A method of obtaining 1,1,2,2-Tetrafluoroethane together with 1,1,2-triptoreline by catalytic hydrogenation of tetrafluoroethylene over restored oxide of Nickel. During the reaction the temperature is maintained at 150oC. the Total yield of these products is 75% [1]

A significant drawback of the known method of obtaining 1,1,2,2-Tetrafluoroethane is the low yield of the target product and the formation of 1,1,2-triptorelin as a by-product. The latter does not find practical application and requires the creation of installation for its neutralization, since the reset of the compounds in environmentally unacceptable. Causes complications and maintain the desired process temperature, since the reaction of hydrogenation of tetrafluoroethylene exothermic.

The problem solved by the present invention is to improve the environmental parameters and the increase in the efficiency of production of 1,1,2,2-Tetrafluoroethane by reducing by-products of the hydrogenation of tetrafluoroethylene and reduction of specific energy consumption.

The problem is solved in that in the method of obtaining 1,1,2,2-Tetrafluoroethane by hydrogenation of tetrafluoroethylene in the presence of catalunan as a catalyst of palladium on alpha-aluminum oxide, when filing the original of the tetrafluoroethylene to hydrogenation in a mixture with indifferent diluent at molar ratio indifferent diluent and tetrafluoroethylene, equal 1-6:1.

In addition, as the catalyst is used preferably industrial alumina-palladium-based catalyst composition, wt. palladium 1,8-2; alumina rest.

As indifferent diluent used is preferably 1,1,2,2-Tetrafluoroethane.

The process is conducted at a molar ratio of hydrogen and tetrafluoroethylene is preferably in the range of 0.9 to 1.2:1.

The process is conducted with the use of preheating of the catalyst by the filing of the original gaseous mixture, heated at least to the 50oC.

Example 1. Hydrogenation of tetrafluoroethylene carried out in a laboratory setup, which includes a reactor made of Nickel with a diameter of 18 and a length of 250 mm, the dosing system of tetrafluoroethylene, hydrogen and gaseous diluent, and condensation products of hydrogenation. The reactor is equipped with a socket for thermocouple and an insulating jacket to prevent heat loss into the environment. Charged to the reactor industrial alumina-palladium catalyst brand APK-2 (TU . The catalyst pre-dehydration in a stream of nitrogen at 350oC for 5 h and restore in a stream of hydrogen at 300oC for 3 hours Pre-heating of the catalyst is carried out by the filing of the original gaseous mixture, heated in factographical established immediately before the reactor. Factographical is a hollow Nickel tube with a diameter of 10 and a length of 300 mm, supplied with external electric heating. The temperature in factographical set in the range of 50-100oC. After establishing the temperature in the reactor over 50oWith formadores disable the hydrogenation process is carried out in adiabatic conditions, continuing the supply of the initial reagents (tetrafluoroethylene and hydrogen) and diluent without preheating. The products of hydrogenation is removed from the reactor, washed with water for cooling and removal of trace quantities of acid components, dried digidrirovanny calcium chloride, condensed in the cylinder, cooled by liquid air, rectificatum laboratory low-temperature column efficiency 40 so so the Duration of the experiment 5 hours, the feed Rate of tetrafluoroethylene and hydrogen at 1 l/h (0.045 mol/h); 1,1,2,2-Tetrafluoroethane - 6 l/h (0,268 Mona and 138 g of 1,1,2,2-Tetrafluoroethane. As a result of condensation obtained 162 g of raw product from which, by low-temperature rectification allocated 161 g of 1,1,2,2-Tetrafluoroethane with a basic substance content of more than 99% 23 g of this amount synthesized in the course of this experience. The yield of the target product from theoretically possible for organic raw materials 94,0%

Examples 2 to 9. Experiments on the hydrogenation of tetrafluoroethylene performed with the setup described in example 1 with the same sequence of operations. Examples 2-5 were conducted under optimal conditions, examples 6-9 to justify the boundary conditions of the optimal mode. The specific conditions and the results of the experiments in all the examples presented in the table.

As can be seen from the table, the implementation of hydrogenation under optimal conditions (examples 1-5) is characterized by the almost complete conversion of the starting materials and the high yield of the target product. Reducing the molar ratio of 1,1,2,2-Tetrafluoroethane to the tetrafluoroethylene below 1 results in adiabatic conditions to the uncontrolled growth temperature, which in turn is accompanied by formation along with the target product side, in particular triptorelin and 1,1,2-triptorelin (example 6). Increase the specified relation over 6 impractical to tetrafluoroethylene below 0.9, as well as the increase over 1.2 leads to incomplete conversion of the starting reagents, which in turn leads to increased consumption of reagents and the resulting decrease of the yield of the target product (examples 8 and 9).

The presented examples demonstrate the effectiveness of the proposed method in comparison with the known. The effect can be explained as follows. Exothermic hydrogenation of tetrafluoroethylene prototype accompanied by the local overheating because the heat effect hydrogenation of tetrafluoroethylene extremely high (65 kcal/mol). Local overheating leads to the decomposition of 1,1,2,2-Tetrafluoroethane with the formation of triptorelin and hydrogen fluoride. The resulting triptorelin in terms of the prototype hereroense to 1,1,2-triptorelin. Adiabatic conditions the proposed method eliminates overheating and decomposition of 1,1,2,2-Tetrafluoroethane with the formation of triptorelin, hydrogen fluoride and 1,1,2-triptorelin. Thanks to improved environmental parameters of the process, increases the efficiency of production of 1,1,2,2-Tetrafluoroethane.

1. The way to obtain 1,1,2,2-Tetrafluoroethane by hydrogenation of tetrafluoroethylene in the presence of a catalyst at elevated temperature, otlichayushiesya palladium on alpha-aluminum oxide, when filing the original of the tetrafluoroethylene to hydrogenation in a mixture with indifferent diluent at a molar ratio indifferent diluent and tetrafluoroethylene, is equal to 1 6 to 1.

2. The method according to p. 1, characterized in that the catalyst used industrial aluminum-palladium catalyst composition, wt.

Palladium 1,8 2

Alumina Rest

3. The method according to p. 1, characterized in that as indifferent diluent used 1,1,2,2-Tetrafluoroethane.

4. The method according to p. 1, wherein the process is conducted at a molar ratio of hydrogen and tetrafluoroethylene in the range of 0.9 to 1.2 1.

5. The method according to PP. 2 and 4, characterized in that the process is conducted with the use of preheating of the catalyst by the filing of the original gaseous mixture, heated at least to the 50oC.

 

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