RU2498852C1 - Catalyst production method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to the technology of producing catalysts containing halogens, catalysts containing fluorides, and specifically to production of a caesium fluoride catalyst CsF, deposited on activated carbon. Described is a method of producing a catalyst, which is caesium fluoride deposited on activated carbon, which involves saturating activated carbon with aqueous caesium fluoride solution and drying, wherein the saturated catalyst is dried for 8-12 hours at temperature of 320-350°C, while alternating processes of blowing dry nitrogen through its layer for 1-1.5 hours and evacuating at 1-5 mm Hg for 10 minutes, after which the catalyst is cooled in a current of dry nitrogen.

EFFECT: high efficiency of the obtained catalyst at relatively low temperatures, maintaining operational properties for a long period of time of more than 800 hours, which enables to carry out processes continuously, as well as relatively easy regeneration.

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Description

The present invention relates to a technology for producing catalysts containing halogens; catalysts containing fluorides, namely, to obtain a catalyst of cesium fluoride CsF supported on activated carbon.

CsF fluorides CsF are known catalysts used for the isomerization and alkylation of various organic compounds, including organofluorine compounds. These catalysts are effective in the processes of isomerization of perforated epoxides into perfluorinated acid fluorides, which are the starting compounds for producing monomers, including fluorohydrides, which are the starting compounds used in the preparation of sulfonomers.

It is known to use cesium fluoride (CsF) supported on AG-3 brand coal for isomerization of hexafluoropropene oxide into perfluoropropionic acid fluoride [a.s. USSR 618936, m.cl .: C07C 58/36, 51/01, publ. November 2, 1976]. The process is carried out at a temperature of 160-200 ° C, the weight ratio of catalyst: activated carbon is 0.1-1: 1. The catalyst is pre-dried for 2 hours in a stream of air at a temperature of 200 ° C. The activity of the catalyst is maintained for 200 hours. The yield of perfluoropropionic acid fluoride is from 96 to 98.5%.

In the work [US Pat. US No. 43238416, 1980, CA] shows the low catalytic activity of cesium fluorides (CsF) supported on activated carbon. In the preparation of such a catalyst, coal impregnated with cesium fluoride (5-7% by weight) was dried at a temperature of 200 ° C.

Closest to the claimed is the catalyst used in the method [and.with. USSR 569554, μl. ² C07C 49/16, publ. 09/27/1977] the production of perfluoroethylisopropyl ketone by the reaction between hexafluoropropylene oxide and hexafluoropropylene in acetonitrile medium, where alkali metal fluoride (cesium fluoride) was used as a catalyst, and the process lasted for 6 hours at a temperature of 20-25 ° C and atmospheric pressure. The yield of perfluoroethylisopropyl ketone was 31%. The interaction is carried out according to the scheme:

The disadvantage of this method is the low yield of the target product. Upon repeating this experiment, a yield of 30% was obtained.

The disadvantages of the above catalysts is that in their composition the residual water content in them in the form of a complex CsF * H ₂ O, which reduces the catalytic activity.

The aim of the invention is to provide a catalyst that is effective at low temperatures, provides a conversion of ≥99% and remains active for up to 800 hours.

The essence of the invention lies in the fact that a method for producing a catalyst comprising cesium fluoride CsF deposited on activated carbon, comprising impregnating activated carbon with an aqueous solution of cesium fluoride and drying, characterized in that the impregnated catalyst is dried for 8-12 hours at a temperature of 320 -350 ° C, with alternating operations of blowing through its layer of dry nitrogen for 1-1.5 hours and evacuating at 1-5 mm Hg for 10 minutes, after which the catalyst is cooled in a stream of dry nitrogen.

After the catalyst has run a full cycle, it can be regenerated. The regeneration process consists in purging the catalyst with nitrogen and evacuating at a temperature of 320-350 ° C. As a result of regeneration, the catalyst completely restores its catalytic activity, which is associated with the destruction of the CsF * H ₂ O and CsF * HF complexes formed during the operation of the catalyst.

The resulting catalyst is effective in the synthesis of perfluoropropionic acid fluoride by isomerization of propylene oxide, its use helps to reduce the synthesis temperature to 35-60 ° C.

The use of a catalyst prepared by the developed method also allows the production of perfluoroethylisopropyl ketone from hexafluoropropene oxide and hexafluoropropene at a temperature of 65-110 ° C, a pressure of 0-0.25 MPa and a ratio of 0.95-1: 0.95-1 mol.

The catalyst is prepared as follows: activated carbon (BAU-2, AG-3, SKT-6) is poured with an aqueous solution of CsF (3-50% by weight) above the coal level by 1-5 mm and then, with stirring, the water is distilled off, after whereby the impregnated carbon is dried at 200-220 ° C in an oven, also with periodic stirring. After 12-18 hours, the catalyst is loaded into the synthesis reactor and at a temperature of 320-350 ° C, dry nitrogen is successively blown through its layer for 1-1.5 hours, then vacuum at 1-5 mm Hg. for 10 minutes. These operations are repeated several times for 8-12 hours, after which the catalyst is cooled in a stream of dry nitrogen. In this case, complete removal of water from coal and CsF is achieved (upon drying with a temperature of 200 ° C, the CsF * H ₂ O complex remains in the system, which, upon isomerization of hexafluoropropene oxide into perfluoropropionic acid fluoride, turns into a CsF * HF complex that does not have catalytic activity:

In addition, the alternation of purging the catalyst with nitrogen and evacuation at 320-350 ° C promotes the dispersion of CsF crystals to sizes less than 100 nanometers and brings it to the surface of the active centers of activated carbon, which significantly increases its catalytic efficiency. Table 1 shows the results of determining the composition of samples carried out by electron probe microanalysis.

Samples:

No. 1 - Activated carbon + CsF, prepared at 200 ° C.

No. 2 - Activated carbon + CsF, prepared at 350 ° C.

The results of the analysis are presented in table 1, and the Figure presents micrographs of samples of catalysts prepared by the known method (No. 1) and according to the invention (sample No. 2). As can be seen from the micrograph of the catalyst samples, in sample No. 2, CsF crystals are deposited on the surface of the catalyst, and not inside, as in sample No. 1.

The resulting catalyst has a high catalytic activity and allows isomerization of hexafluoropropene oxide to perfluoropropionic acid fluoride even at a temperature of 35-60 ° C with a conversion of ≥99%:

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The use of a new catalyst in the process of producing perfluoroethyl isopropyl ketone (PFEIC) by the interaction of hexafluoropropene oxide with hexafluoropropene allows the process to be carried out at a lower temperature, in the range of 70-120 ° C and with a yield of 94-95%:

EXAMPLE 1

Experience 1-12. A pre-prepared catalyst, namely activated carbon of the BAU-2, AG-3 or SKT-6 (50-58 g), impregnated with cesium fluoride (1.5-29 g) with a weight ratio of 1: 0.03-1: 0.5. The cesium fluoride solution is filled by 1-5 mm above the coal level and then, with stirring, water is distilled off, after which the impregnated coal is dried at 200-220 ° C in an oven also with periodic stirring. After 12-18 hours, the catalyst is loaded into the synthesis reactor and, at a temperature of 320-350 ° C, dry nitrogen is successively blown through the coal layer for 1-1.5 hours, then vacuum at 1-5 mm Hg. for 10 minutes. These operations are repeated for 8-12 hours, after which the catalyst is cooled in a stream of nitrogen. After cooling the reactor to a working temperature of 35-60 ° C, hexafluoropropene oxide is supplied to an excess pressure of 0.1 MPa to activate the catalyst. After an hour, hexafluoropropene oxide is fed into the reactor at a speed of 30-200 cm ³ / min at a pressure of 0-0.25 MPa. The main results are shown in table 2.

Experience 13 (comparative)

Similarly (experiment 1-12), a reaction is carried out using CsF supported on activated carbon AG-3 in a weight ratio of 1: 1 as a catalyst.

EXAMPLE 2

Experience 14-22. In a tubular reactor made of steel 12X18H10T with a length of 1500 mm, a diameter of 150 mm and equipped with electric heating and an internal heat exchanger, with a diameter of 57 mm and a length of 1430 mm, cooled with running water, filled with activated carbon BAU-2, containing 5% weight. CsF and prepare for work by the method described above. Hexafluoropropene oxide is supplied at a speed of 2-4 kg / h at a temperature of 35-60 ° C. Table 3 shows the results of the effectiveness of the catalyst depending on the operating time and shows the efficiency of regeneration.

EXAMPLE 3

Experience 23-33. Tubular reactors made of steel 12X18H10T with a length of 500 mm, a diameter of 38 mm, equipped with electric heating and an internal heat exchanger, with a diameter of 20 mm and a length of 470 mm, cooled by running water heated to a temperature of 35-60 ° C and a reactor with a length of 500 mm and a diameter of 50 mm, heated to a temperature of 65-110 ° C is filled with activated carbon BAU-2, containing 5-7% by weight. Csf. The prepared mixture consisting of hexafluoropropene oxide and hexafluoropropene in a molar ratio of 1: 1-1.03 is supplied at a speed of 60-200 cm ³ / min at a pressure of 0-0.25 MPa. The reaction product is collected in a trap, cooled to -20 ° C. The results of the experiments are shown in table 4.

The advantages of the proposed catalyst include its high efficiency at relatively low temperatures, the preservation of operational properties for a long time ≥800 hours, allowing continuous processes, as well as the relative ease of regeneration. Alternating the purge of the catalyst with nitrogen and evacuation at 320-350 ° C promotes the dispersion of CsF crystals to sizes less than 100 nanometers and brings them to the surface of the active centers of activated carbon, which significantly increases its catalytic efficiency.

As can be seen from the experiments in the tables, the most successful catalyst is CsF supported on activated carbon (BAU-2, AG-3, SKT-6), prepared at a temperature of 320-350 ° C under vacuum and with a nitrogen purge, which allows isomerization hexafluoropropene oxide to perfluoropropionic acid fluoride even at a temperature of 35-60 ° C with a conversion of ≥99%, as well as obtaining PFEIC at a temperature of 65-110 ° C with a yield of up to 95%. The resulting perfluoropropionic acid fluoride is used in the synthesis of sulfomonomers.

The developed catalyst retains catalytic activity for 800 hours of operation.

Table 1 X-ray microanalyzer readings No. S Cl K Ca Cs F Cs / f Formula one 0.2 0.05 0.3 0.7 5.2 1,5 3,5 CsF * HF 2 0.1 - 0.4 0.5 6.3 0.9 7.0 Csf

table 2 Hexafluoropropene oxide isomerization on a CsF / activated carbon catalyst Experience number Brand Activ. coal CsF,% weight. T, ° C Hexafluoropropene Oxide Conversion The yield of fluorohydride one BAU-2 2 35 76 76 AG-3 2 35 75.8 75.7 SKT-6 2 35 76.5 76.3 2 BAU-2 3 35 95.3 95.3 AG-3 3 35 94.8 94.8 SKT-6 3 35 95.5 95.5 3 BAU-2 3 45 one hundred one hundred AG-3 3 45 one hundred one hundred SKT-6 3 45 one hundred one hundred four BAU-2 5 45 one hundred one hundred AG-3 5 45 one hundred one hundred SKT-6 5 45 one hundred one hundred 5 BAU-2 5 60 one hundred one hundred AG-3 5 60 one hundred one hundred SKT-6 5 60 one hundred one hundred 6 BAU-2 5 75 one hundred 98.5 AG-3 5 75 one hundred 98.3 SKT-6 5 75 one hundred 98.6

7 BAU-2 5 one hundred one hundred 92 8 BAU-2 10 60 one hundred one hundred 9 BAU-2 fifteen 60 one hundred one hundred 10 BAU-2 twenty 60 one hundred one hundred eleven BAU-2 30-50 60 one hundred 99 12 SKT-6 fifty 160 one hundred 45 13 AG-3 one hundred 60 22 10 AG-3 one hundred one hundred 65 eighteen AG-3 one hundred 160 98 32

Table 3 The conversion of hexafluoropropene oxide on the catalyst is (5% wt.) CsF / activated carbon BAU-2, depending on the operating time Experience number Process time, hour Conversion of hexafluoropropene oxide to perfluoropropionic acid fluoride fourteen one hundred one hundred fifteen 300 one hundred 16 700 one hundred 17 800 97.1 eighteen 900 87.3 19 1000 71.2 After catalyst regeneration twenty one hundred one hundred 21 400 one hundred 22 750 99

Table 4 Synthesis of perfluoroethylisopropyl ketone on a CsF catalyst (5-7% weight) supported on BAU-2 activated carbon Experience number Process temperature ° C Impurities,% of the mass. The content of PFEIC,% wt. The yield of PFEIC,% wt. 1st reactor 2nd reactor 23 35 65 3,5 96.5 94.5 24 fifty 65 2,5 97.5 95 25 60 65 2,5 97.5 95 26 60 80 2.49 97.51 95 27 60 90 2,51 9.49 95 28 80 65 6 94 92.8 29th one hundred 80 7.9 92.1 90,4 thirty 125 80 10.3 89.7 88.1 31 60 90 2,52 97.48 95 32 60 110 2.54 97.46 94.49 33 60 125 2.75 97.25 94.38

Claims (1)

A method of obtaining a catalyst comprising cesium fluoride deposited on activated carbon, comprising impregnating activated carbon with an aqueous solution of cesium fluoride and drying, characterized in that the impregnated catalyst is dried for 8-12 hours at a temperature of 320-350 ° C, with alternating blowing operations through its layer of dry nitrogen for 1-1.5 hours and evacuation at 1-5 mm Hg for 10 min, after which the catalyst is cooled in a stream of dry nitrogen.

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