Method of regeneration of the chromium catalyst fluorination

 

(57) Abstract:

Usage: in the petrochemical industry, in particular in the way of recovery of spent chromium catalyst fluorination. The inventive method provides for the processing of spent chromium catalyst fluorination gas mixture containing hydrogen fluoride and up to 30 mol. % air (it is better to take the ratio of the hydrogen fluoride and air, at least to 0.1 : 1, preferably (2 - 100) at 300 - 500°C (preferably at 330 - 450°C). The gas mixture may contain from 70 to 99.9 mol. % hydrogen fluoride, and optionally an inert diluent. 5 C.p. f-crystals, 2 tab.

The subject of the invention is a method for regenerating catalyst for fluorination.

The known process of interaction of fluoride with various organic compounds for introduction into one or more fluorine atoms. For example, the known process of interaction of fluoride with various carbon compounds, such as trichloroethylene or 1,1-Cryptor-2-chlorate order to obtain 1,1,1,2-Tetrafluoroethane (FA 134a). When carrying out these reactions usually applies a known catalyst for the fluorination. The activity of these catalysts is degraded in the process Fofanova catalyst with air for burning organic pollutants. This operation is highly exothermic and, in order to avoid the use of expensive cooling systems and be able to use the adiabatic catalyst bed, the air supply is often regulated by using thinner; commonly used diluent is nitrogen. After using nitrogen as such, he is thrown into the atmosphere, but the presence in the outlet gas of organic pollutants can cause problems associated with environmental pollution.

It was found that waste fluorination catalysts can be successfully regenerated using mixtures of air or other oxidant and hydrogen fluoride, with the exhaust gases from the regenerating and containing hydrogen fluoride, used in the fluorination reactions.

For a simpler presentation of the essence of this invention, it is described with an indication of air as oxidant, but instead of air, you can use any oxidizing agent containing oxygen.

In accordance with the invention provides a method of regenerating catalyst fluorination after its use in the fluorination reaction, and the method includes kontaktirajte, the mixture contains up to 30% of the air in molar terms.

Regeneration in accordance with the method according to the invention are subject in particular catalysts used to catalyze the reaction of hydrogen fluoride with a halogenated hydrocarbons, especially chlorinated olefins, such as trichloroethylene or chlorinated alkanes such as 1,1,1-Cryptor-2-chlorate. Applied catalysts for fluorination comprehensively described in the prototypes and include various inorganic compounds such as oxides and halides of such metals as aluminum, cobalt, manganese, iron and especially chrome. Acceptable chromium catalysts include the oxide, hydroxide, halides, oxychloride, inorganic salts, basic chromium fluoride and known catalysts.

The composition of the mixtures used for the regeneration of the catalyst may vary within wide limits depending on whether in this mix diluent such as nitrogen. If the diluent, representing the nitrogen is not present in this mixture, the hydrogen fluoride is at least 70% of the mixture in molar terms, and the content of hydrogen fluoride is usually from 70 to 99.9% in molar terms. If the mixture has come and moreover, the content of hydrogen fluoride is preferably such that the molar ratio of hydrogen fluoride and air is 0.1:1. Thus, this mixture contains hydrogen fluoride and air in a molar ratio equal at least to 0.1:1, preferably 1:1 and preferably 2: 1, for example, 2-100:1. Typically, the molar ratio of hydrogen fluoride and air decreases with increasing content of the diluent.

Preferred compositions also to some extent depend on the type of catalyst layer. In the case of adiabatic layers preference is given to mixtures of air and hydrogen fluoride containing 10% air in molar terms, with a typical mixture contains about 2% of the air. In the case of tubular reactors with cooling permissible higher air content, for example up to 30% in molar terms.

A mixture of standing out of the air, fluoride, and optional diluent may also include small amounts of organic substances, for example up to 1% in molar terms, the starting compounds and/or intermediates and/or products formed during the fluorination. So, for example, hydrogen fluoride and/or diluent may be released for re-espol, of fluoride and diluent may continue during the period of time necessary to achieve the required degree of regeneration of the catalyst, with the preferred temperatures are in the range from 330 to 450aboutC. the Flue gases generated in the process of regeneration, then preferably are recirculated without cooling in the fluorination reactor or used in another reaction fluoridation.

In the known processes the regenerated catalyst usually is pre-fluoridation prior to its re-introduction in the fluorination reaction. The advantage of this method of regeneration of the catalyst according to the invention is that, since the regeneration process is applied fluoride, eliminating the need for additional preliminary fluorination catalyst. Another advantage of the method according to the invention, which is partly due to the lack of necessary preliminary fluorination of the regenerated catalyst, is that in the process of regeneration of the catalyst and its re-use there are no significant losses of chromium, there is no oxidation of the compounds of CR (III) volatile and toxic compounds Cr (VI), or education Tora this disadvantage is a distinctive feature.

In a preferred embodiment of the invention the mixture of hydrogen fluoride and ftorirovannogo material is supplied alternately to the two layers of catalyst, arranged in parallel, while not currently in use, the layer of catalyst is subjected to regeneration in accordance with the method according to this invention.

The invention is illustrated by, but is not limited to the following examples.

P R I m e R 1. Chrome fluorination catalyst after use in the process of obtaining 1,1,1,2-Tetrafluoroethane by fluorination of 1,1,1-Cryptor-2-chlorethane, was heated for 2 hours at a temperature of 400aboutIn the environment of fluoride. The mixture of hydrogen fluoride and air in a molar ratio of 50:1 was passed over the catalyst for 6 hours at a temperature of 400aboutC. the catalyst was observed aksiomaticheski effect in terms of the temperature increase on the 50aboutC.

After the end of the regeneration air flow was stopped and the catalyst was cooled for 2 hours to the appropriate temperature fluorination.

P R I m m e R 2. 200-gram sample of the chromium catalyst was placed in a reactor made of Inconel with a diameter of 2 inches, set in the oven. The catalyst was heated to 350aboutis the group of 1:3.5. Waste gases from the reactor, was filed in the scrubber for washing gases periodic action, in which using atomic adsorption analysis has established the level of chromium. In the solution in the scrubber, after 16 h was not detected chromium (see example 1 in table. 1).

The feed mixture of compound a and fluoride was stopped after 16 h, after which the reactor was purged and heated to 400aboutC. In the scrubber changed the water, and the reactor was fed a mixture of hydrogen fluoride and air with a molar ratio of 20: 1. The formed product from the reactor was filed in the scrubber for washing gases and as well, as described above, analyzed the level of chromium in the scrubber. We measured the total quantity of chromium accumulated in the scrubber during the first 16 h of regeneration, which turned out to be below the detection threshold (see example 2 in table. 1). In a subsequent study, the catalyst was regenerated for more than 72 hours instead of 16 hours, while the scrubber was not detected chromium (see example 3).

The method according to the invention was then compared with the usual sequence of operations regeneration and re-fluorination. This sequence of operations regeneration consisted of initial heating of the catalyst to air the ohms on regenerated in air, the catalyst leads to high losses, chromium (see examples 5 and 6, and comparative studies 7 and 8, and examples 6 and 8 were obtained at various flow rates of hydrogen fluoride, which indicate periods of contact with the catalyst).

After the implementation of the reaction (see example 9) were produced two regeneration air diluted with nitrogen, and the obtained results are presented in examples 10 and 11, and 12 and 13. There was a significant loss of chromium from the catalyst.

After completion of the reaction (see example 14) was performed several regenerations mixture of hydrogen fluoride and air at a higher flow rate and a shorter time of contact with the catalyst. Again we observed a very low loss of chromium even at the highest flow rates (see examples 15 to 18).

Finally, the use of a mixture of hydrogen fluoride and air with a higher ratio equal to 1:1, allowed us to demonstrate that at low ratio of hydrogen fluoride and air loss chromium become significant (see example 19).

P R I m e R 3. 10 kg of chrome fluorination catalyst was loaded into solanoideae reactor with a diameter of 3 inches. The catalyst was treated by passing 5 kg of hydrogen fluoride in torecan), resulting in a molar ratio of the supplied mixture of hydrogen fluoride and compounds a was equal to 3.0:1. When created in the reactor pressure 13 bar g temperature of the catalyst was raised to 320aboutWith that allowed to reach 12% conversion connection a in connection 134a. The time of contact in the reactor under the reaction conditions was equal to about 10 C. as deactivation of the catalyst in the reactor was increased temperature with the aim of saving 12% of the reaction product yield 134a. After 90 hours, the catalyst was deaktivirovana, after which the flow connection a stopped. The reactor was heated to 380aboutWith simultaneous purging of the catalyst a stream of hydrogen fluoride.

Then in a stream of hydrogen fluoride was added to the air with a mixture of hydrogen fluoride and air in a molar ratio of 40:1. The catalyst was regenerated under these conditions for 16 h, after which the air supply was stopped, and the temperature of the reactor was returned to 300aboutC. was Resumed its connection a with achievement of the initial molar ratio of hydrogen fluoride and compounds a equal to 3:1. The temperature of the catalyst, if necessary, again increased with the aim of saving 12% of output connections 134a. Working period after regeneration, powdered and air was repeated for 3 cycles.

The efficiency of the regeneration process of the mixture of hydrogen fluoride and air, which was determined based on the duration of the subsequent period of reaction, compared with the regeneration produced by the mixture of nitrogen and air. After the 5th of the working period, the regeneration is again produced at a temperature of 380aboutWith, the flow of hydrogen fluoride was replaced with equimolar flow of nitrogen with the formation of a mixture of nitrogen and air with a molar ratio of 40:1. After 16 h the regeneration temperature of the catalyst is brought up to 300aboutC, the catalyst was re ferromoly the fluoride and made a connection a as described above. As can be seen from the results given in table. 2, there was a gradual reduction of the working period of the catalyst when performing regeneration with a mixture of nitrogen and air.

P R I m e R 4. 10 kg of catalyst was loaded into the adiabatic reactor. The temperature of the catalyst in an adiabatic reactor was increased to 250aboutWith by feeding the pre-heated nitrogen. Then the catalyst was ferromoly using 5 kg of hydrogen fluoride, as described in example 3. Nitrogen was added to the stream of hydrogen fluoride at the stage of preliminary fluorination in order to limit the temperature of the catalyst is less than the use of supplied hydrogen fluoride. Then the flow of hydrogen fluoride was added connection a to form a reaction mixture with a molar ratio of hydrogen fluoride and compounds a equal to 3:1. The temperature of the catalyst was increased by adjusting the inlet temperature of the feed material to achieve 12% of output connections. The necessary conversion was achieved at an input temperature of approximately 330aboutC. the Reaction selectivity ratio connections 134a at the level of 98-99% was maintained for 100 hours, while the temperature of the catalyst to compensate for deactivation of the catalyst.

Then the catalyst was regenerated in accordance with the method according to the invention. This method included the supply connection a and the flow of hydrogen fluoride, preheated to 350aboutWith, for regulating the temperature of the catalyst intended for regeneration. In a stream of hydrogen fluoride was gradually introduced air. The adiabatic temperature rise during regeneration led to an increase in the temperature of the catalyst from 350 to 380-400aboutWith using the mixture of hydrogen fluoride and air with the molar ratio of (20-50):1. The allocation of chromium during regeneration of the catalyst was determined by the OTB is but 5 hours the catalyst in the reactor was cooled to 350aboutWith the weaker the reaction regeneration. Then stop the air supply, and the temperature of the stream of hydrogen fluoride brought up to 330aboutS, after which the catalyst was ready for the beginning of the next cycle of transformation connection a. Was resumed its connection a, it was found that the regenerated catalyst provided output connections 134a at the level of 12-14% at a temperature of 330aboutC.

Chrome catalyst was successfully regenerated without detection of a chromium catalyst at the outlet of the scrubber. This method of regeneration is also allowed to avoid large quantities of nitrogen in the discharge equipment, it should be noted that this distinctive feature is especially valuable when the parallel application of two or more reactors with a total exhaust system, so as unreacted starting materials together with products representing the connection 134a and Hcl, which are working reactors, not diluted by large quantities of nitrogen applied for the regeneration of the backup reactor.

P R I m e R 5. Comparative example.

The catalyst regenerated in accordance with example 4, exploited what aboutC. a Stream of hydrogen fluoride was replaced by a similar stream of nitrogen. After the temperature of the catalyst has reached 350aboutWith, for regeneration of the catalyst to nitrogen was added air. When using a mixture of nitrogen and air with a molar ratio of (20-50):1 arose exothermic effect with increasing temperature at the 50aboutWith, then this exothermic effect was weak for 5-6 hours Then stopped the air supply and resumed the supply of fluoride. Checked the chromium content in the scrubber, and the results showed that in the process of regeneration and re-fluorination catalyst in the reactor is fixed reduction of chromium 15,

1. METHOD of REGENERATION of CHROMIFEROUS FLUORINATION CATALYST by treating the spent catalyst with a gas mixture comprising hydrogen fluoride at elevated temperature, characterized in that use gaseous mixture containing hydrogen fluoride and up to 30 mol% of air, and the treatment is conducted at 300 to 500°C.

2. The method according to p. 1, characterized in that use gaseous mixture containing hydrogen fluoride and air in a molar ratio of at least 0.1 to 1.

3. The method according to p. 2, characterized in that ispolzuut, characterized in that use gaseous mixture containing 70,0 to 99.9 mol. hydrogen fluoride.

5. The method according to PP.1 to 4, characterized in that use gaseous mixture containing optionally an inert diluent.

6. The method according to PP. 1 to 5, characterized in that the processing carried out at 330 - 450oC.

 

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