DE1468971C - Process for the continuous production of chlorofluoromethanes - Google Patents

Description

The following examples serve to illustrate the invention in greater detail.

example 1

Conversion of methane 99%

Conversion of Cl, 97.9 ° / ₀

HF conversion 99%

Net yields at:

The apparatus used for the chlorofluorination reaction consists essentially of two in series switched reactors and a distillation column, both apparatus for working under pressure are suitable.

In the first metal reactor, which contained 372 ecm of activated carbon with a size of 0.2 to 0.3 mm supported by a porous metal plate, a gas mixture ^{was introduced at a temperature of 470 ° C. and a pressure of 4 kg / cm 2} from chlorine, hydrofluoric acid, methane and a reflux mixture of halogenated hydrocarbons in accordance with the following molar ratios:

Chlorine 4.09 mole percent

Hydrofluoric acid 1.58 mole percent

Methane 1 mole percent

Return mixture of halogenated hydrocarbons .. 5.8 mole percent

The reflux mixture of the halogenated hydrocarbons had the following molar composition:

CCl ₄ 61.3 mole percent

CFCl ₃ 35.6 mole percent

CHCl ₃ 1.9 mole percent

CF ₂ Cl ₂ 0.1 mole percent

CH ₂ Cl ₂ 0.08 mole percent

CHFCl ₂ 0.01 mole percent

C ₂ Cl ₄ 0.3 mole percent

The contact time of the gases in the catalytic zone was 1.76 seconds.

The gas mixture coming out of the reactor was then passed into the second metal reactor, which contained 220 ecm of fluorinated aluminum oxide with a size of 0.1 to 0.16 mm and at 235 ° C was held.

The contact time of the gases in the second catalytic zone was 1.44 seconds. At the exit of the second In the reactor, the gaseous mixture was passed into a distillation column, the top of which was filled with salt water was cooled from about -10 ° C.

A liquid mixture of the products was collected at the bottom of the column, which was then transferred to a measuring pump driven off, evaporated and returned as a reflux mixture while from the head a gaseous mixture emerged from the column, which was the raw material and which was washed and then was fractionally condensed.

The molar composition of the mixture of reaction products emerging from the top of the column was the following:

HCl 83.23 mole percent

HF 0.22 mole percent

Cl ₂ 1.29 mole percent

CF ₃ Cl 0.14 mole percent

CF ₂ Dl ₂ 8.18 mole percent

CFCl ₃ 6.40 mole percent

CHCl ₃ 0.01 mole percent

CH ₄ 0.12 mole percent

The conversions of the various substances and the yields of chlorofluorinated products, calculated on the converted methane, were the following:

60

CF ₃ Cl 1%

CF ₂ Cl ₂ 55%

CFCl ₃ 43%

The yield of the catalyst was 7.22 moles of chlorofluorohydrocarbons per liter of the catalyst per hour.

Example 2 (comparison)

Using the same apparatus as in Example 1, a comparative experiment was carried out on ordinary Pressure carried out. The composition of the reflux mixture and the molar ratios the reactants were the same as in Example 1.

The pressure was 764 mm / Hg.

The temperature of the first reactor was 470 ° C and the contact time was 1.49 seconds. The temperature of the second reactor was 230 ° C and the contact time 1 second.

The top of the column was cooled with trichlorethylene and dry ice at about -35 ° C. The received Conversions and yields were practically the same as in Example 1.

The yield of the catalyst was 2.02 moles of chlorofluorocarbons per liter of the catalyst per hour.

Example 3

A gaseous mixture of chlorine, hydrofluoric acid, methane and a gaseous reflux mixture in the following molar ratios was introduced into a reactor which contained 412 ecm of _{activated carbon impregnated with 15% AlF 3} and 2% ThF _{4 with a shape size of 0.16 to 0.6 mm} :

Chlorine 4.13 mole percent

Hydrofluoric acid ... 1.62 mole percent

Methane 1.0 mole percent

Gaseous reflux mixture 5.85 mole percent

The pressure was 6 kg / cm ² .

The gaseous reflux mixture had the following molar composition:

CCl ₄ 54.3 mole percent

CHCl ₃ 0.2 mole percent

CH ₂ Cl ₂ 0.07 mole percent

CFCl ₃ 44.6 mole percent

CF ₂ Cl ₂ 0.1 mole percent

CHFCl ₂ 0.3 mole percent

C ₂ Cl ₄ 0.08 mole percent

C ₂ Cl ₆ 0.01 mole percent

The temperature of the reactor was 465 ° C. and the contact time of the gases in the catalysis zone was 2.57 seconds.

At the exit of the reactor, the reaction products were introduced into a distillation column, ^{still under a pressure of 6 kg / cm 2, leading to}

was suitable for working under pressure and the head of which was ^{cooled with cold water of about 0} ° C.

The reflux mixture was collected at the bottom of the column and expelled by a measuring pump, evaporated and returned again.

A mixture of the reaction products with the following molar composition was discharged from the top of the column receive:

HCl 81.89 mole percent

HF 0.94 mole percent

Cl ₂ 2.41 mole percent

CF ₃ Cl 0.10 mole percent

CF ₂ Cl ₂ 7.77 mole percent

CFCl ₃ 6.68 mole percent

CHCl ₃ 0.01 mole percent

CH ₄ 0.14 mole percent

CHF ₂ Cl 0.01 mole percent

The conversion of the reactants and ao the yields of chlorofluorinated products, based on the converted methane were as follows:

Conversion of the CH ₄ 99%

Conversion of the Cl ₂ 96% as

HF conversion 96%

Net yields at:

CF ₃ Cl 0.8%

CF ₂ Cl ₂ 53.2%

CFCl ₃ 45.8%

The yield of the catalyst was 11.9 moles of chlorofluorohydrocarbons per liter of the catalyst per hour.

B e i s ρ i e 1 4 (comparison)

The experiment described in Example 3 was repeated for comparison, but under atmospheric pressure was worked, d. H. exactly at 765 mm / Hg.

The composition of the reflux mixture, the molar ratios of the reacting substances and the Reaction temperatures were essentially the same as in Example 3, while the contact time was 2 seconds fraud.

Conversions and net yields were practically the same as those obtained in Example 3.

The head of the column was made with trichlorethylene and * Dry ice chilled to about -35 ° C.

The yield of the catalyst was 2.31 moles of chlorofluorohydrocarbons per liter of the catalyst per hour.

Claims (1)

1 2 PatentansDruch · continuous production of chlorofluoromethanes by reacting methane, chlorine and fluorine process for the continuous production of hydrogen in the gas phase in the presence of a chlorofluoromethane by reacting a mixture of recycled halogenated hydrocarbon, chlorine and hydrogen fluoride in the gas phase 5 substances and in the presence for the chlorofluorination in the presence of a mixture recycled halogen catalysts at a temperature of 200 to emitted hydrocarbons and in the presence. 500 ⁰ C and with a residence time of less than for the chlorofluorination conventional catalysts at 15 seconds. The process is characterized in that the reaction is carried out at a temperature of 200 to 500 "C and at a pressure, residence time of less than 15 seconds, since 2 to 15 kg / cm ² , and the gaseous state is characterized in that the reaction mixture is introduced under pressure into a distillation reaction at a pressure of 2 to 15 kg / cm ² , which is carried out at the top and the gaseous reaction mixture partially condenses the gaseous end product mixture by cooling under pressure in a distillation column and in Usually worked up,, introduces, at the top of which the gaseous 15 while at the bottom of the distillation column the end product mixture is partly removed by cooling down the reflux mixture and condensed in gaseous form into the and worked up in the usual way, chlorofluorination is returned,
during map at the bottom of the distillation column. If you work according to the present invention, the reflux mixture decreases and is in gaseous form so those coming from the reaction vessel are returned to the chlorofluorination. 20 the gases introduced into the distillation column “^ _. always under such pressure conditions that a simple cooling for example by means of cold Depending on the pressure of the gases, water is sufficient to partially condense the reaction According to a known method (cf. Belgian 35 products to be achieved. With this procedure, patent specification 622 167) it is possible to avoid fluorinated and the compression of the reaction gases when leaving the reactor, in particular chlorofluorinated organic compounds, since these gases are always at a high reaction rate and there are large amounts required, which are suitable for partial recovery by the reaction of hydrofluoric acid, condensation in the distillation column. Chlorine, methane and a mixture of halogenated 3 ° In this way, the use of Kompres hydrocarbons in the presence of catalysts can be made of chemically very resistant materials, whereby the halogenated hydrocarbons are no longer required, as was the case with the substances previously used after the end of the Reaction unchanged known procedure was the case.
are present and are continuously recycled As already explained above, the gases can, can. This process, which is practically carried out at atmospheric pressure that must react, namely hydrofluoric acid, gives very good chlorine, methane and the reflux mixture, easily and yields of valuable products, and shows a high yield per unit volume of des, easily fed to the reaction vessel under pressure Catalyst. will. Chlorine and hydrofluoric acid can, however, have some difficulties in separating the reaction products from the process by adding the usual liquid phase pumps; the methane is advantageously mixed with the returned halogenated carbon to the required pressure by means of a suitable hydrogen. . The separation of the reaction products, which have a corrosive effect, while the possible reflux mixture of the recycled halogenated carbon mixture that comes from the bottom of the distillation column forms hydrogen, is generally carried out by 45 and which always occur Distillation at the previously set pressure. is supplied by means of an ordinary pump Because of the high value of the heat of condensation. of the vapors of the fluorinated and chlorofluorinated It was found that the residence time of the inorganic Compounds in the reaction mixture catching gas mixture on the catalyst (contact time) it would be very desirable to continue the distillation under pressure 50 for a period of up to less than 15 seconds, can be varied and that with longer such a distillation is all the cheaper and contact times chlorofluorinated compounds are obtained more economical, the higher the pressure is kept, there will be those with a higher halogen content, Such high pressure conditions the use In this way, the contact time changes in Absehr Cheaper coolant to cool the head depending on which of the different chlorine stripping columns enable, such as water. fluorinated derivatives are predominantly obtained In order to carry out the distillation under high pressure. In order to be able to carry out the mixture, it has surprisingly been found that the gases resulting from the reaction can be compressed by means of a compressor according to the method of the present invention which consists of a special material besides many practical advantages (easier cooling must, which withstands the strong head of the distillation column using corrosive gases such as HCl, HF, Cl ₂ , very cheap coolants, no compression phase in the gas stream coming out of the reaction device between the reactor outlet and the inlet - Distillation column, increased productivity per dishes with special properties such as chemical weight unit of the catalyst) is possible, also shear resistance must be used, higher conversions with higher yields which means a considerable disadvantage. desired products even with extremely short ones; The subject of F.rfindiing is a seduction for contact times / u received.