ES2688622T3 - Catalytic fluorination in gas phase from 1230x to 1234f - Google Patents

Abstract

A process for preparing 2,3,3,3-tetrafluoropropene, which comprises contacting 1,1,2,3-tetrachloropropene with hydrogen fluoride in the gas phase in the presence of a chromium fluorination catalyst, and an oxidizing agent that it contains oxygen which is pure oxygen gas or oxygen-containing gas, said oxidizing agent that is in an amount of 0.005 to 3% in mol of oxygen relative to 1,1,2,3-tetrachloropropene, under conditions sufficient to produce directly, in a single reactor, a reaction mixture comprising 2,3,3,3-tetrafluoropropene and at least one compound of formula CF3R, where R is selected from -CCl> = CH2, -CF2-CH3, -CFClCH3 and CHF-CH2F ; removing the HCl from said reaction mixture; separating 2,3,3,3-tetrafluoropropene from said reaction mixture; and recycling the hydrogen fluoride from the reactor, at least one compound of formula CF3R, where R is selected from -CCl> = CH2, -CF2-CH3, -CFClCH3 and -CHF CH2F in which said fluorination catalyst is activated with fluoride of hydrogen at a pressure greater than 10.34 bar (150 psi).

Description

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DESCRIPTION

Catalytic fluorination in gas phase from 1230x to 1234f Field of the invention

The present invention relates to the gas-phase catalyzed fluorination of 1,1,2,3-tetrachloropropene (1230xa) to produce 2,3,3,3-tetrafluoropropene (1234yf). More particularly, the present invention relates to processes in which 1230xa; which optionally contains a low level of polymerization inhibitor, is contacted with hydrogen fluoride (hereinafter referred to as "HF") in a gas phase reaction, in the presence of a fluorination catalyst to produce 1234yf. It is known that the desired product, 1234yf, has utility as a foaming agent, coolant, aerosol propellant, heat transfer medium, fire extinguisher, etc. In addition, 1234yf is known to have zero ozone depletion potential (ODP) and very low global warming potential (GWP) of much less than 150.

Background of the invention

The Montreal Protocol for the protection of the ozone layer stipulated the gradual elimination of the use of chlorofluorocarbons (CFCs). More "friendly" materials for the ozone layer, such as hydrofluorocarbons (HFCs), for example, HFC-134a replaced chlorofluorocarbons. The latest compounds have been shown to be greenhouse gases, which cause global warming and were regulated by the Kyoto Protocol on Climate Change. With the continuing concern about global climate change, there is a growing need to develop technologies to replace those with high ozone depletion potential (ODP) and high global warming potential (GWP). Although hydrofluorocarbons (HFCs), which are compounds that do not reduce ozone, have been identified as alternatives to chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) as solvents, cleaning agents and heat transfer fluids, they still tend to have a GWP significant. Hydrofluoroolefins have been identified as potential alternatives with zero ODP and low GWP.

Methods for preparing hydrofluoroalkenes are known. For example, W02007 / 079431 describes processes for the production of fluorinated olefins, which include hydrofluoropropenes. The processes that are widely described as a single reaction or two or more reactions involve the fluorination of the compound of formula C (X) mCCl (Y) nC (X) to at least one compound of formula CF3CF = CHZ, where each X, Y and Z are independently H, F, Cl, I or Br and each m is independently 1, 2 or 3 and n is 0 or 1.

WO2008 / 054781 describes a variety of processes for producing a variety of fluoropropane and halofluoropropenes by the reaction of halopropanes or halopropenes with HF optionally in the presence of a catalyst.

US 2007/197842 describes processes for the production of fluorinated olefins. Three stages are used in which a raw material of CCl2 = CClCH2Cl is fluorinated to synthesize a compound such as CF3CCl = CH2. CF3CCl = CH2 is converted to CF3CFClCH3 using an SbCl5 as the catalyst that is then selectively transformed into 1234yf.

Summary of the invention

The present invention is directed towards a gas phase catalyzed reactor process for the fluorination of 1,1,2,3-tetrachloropropene (1230xa) to produce 2,3,3,3-tetrafluoropropene (1234yf). The process of the present invention is a catalytic gas phase fluoridation.

The present invention provides a process for preparing 2,3,3,3-tetrafluoropropene, comprising:

contacting 1,1,2,3-tetrachloropropene with hydrogen fluoride in the gas phase in the presence of a chromium fluorination catalyst, and an oxygen-containing oxidizing agent that is pure oxygen gas or oxygen-containing gas in an amount of 0.005 to 3% in mol of oxygen relative to 1,1,2,3-tetrachloropropene, under conditions sufficient to directly produce, in a single reactor, a reaction mixture comprising 2,3,3,3-tetrafluoropropene and at least a compound of formula CF3R, where R is selected from -CCl = CH2, -CF2-CH3, -CFClCH and CHF-CH2F;

removing HCl from said reaction mixture;

separating 2,3,3,3-tetrafluoropropene from said reaction mixture; Y

recycle in the reactor hydrogen fluoride, at least one compound of formula CF3R, where R is selected from -CCl = CH2, -CF2-CH3, -CFClCH and -CHF CH2F

wherein said fluorination catalyst is activated with hydrogen fluoride at a pressure greater than 10.34 bar (150 psi).

The process of the invention employs a high surface area Cr based catalyst that is not

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supported or supported (such as fluorinated alumina, activated carbon, graphite or fluorinated graphite). The catalyst may optionally contain a low level of one or more cocatalysts such as salts of Co, Zn, Mn and Ni. A preferred cocatalyst is nickel. Prior to use, the catalyst is subjected to high pressure HF activation, greater than about 10.34 bar (150 psi), as described in U.S. Pat. No. 7,485,598.

It was found that the resulting activated catalyst catalytically induced two different chemical processes concurrently: adding HF to an olefin such as 1230xa and removing HF from a saturated compound such as 1,1,1,2-tetrafluoro-2-chloropropane (244bb) , 1,1,1,2,2-pentafluoropropane (245cb) and / or 1,1,1,2,3-pentafluoropropane (245eb). The level of conversion and selectivity of the desired product may vary according to the processing conditions. A feature of the present invention is the use of a single catalyst in a single reactor that can defluor co-products such as 245cb and / or 245eb in a recycle stream in the desired product, 1234yf. In addition, other co-produced fluorinated intermediates such as 1233xf and 244bb that are produced as part of the fluorination reaction can also be recycled to the reactor. The process of the present invention can be executed continuously. The deterioration or deactivation of the catalyst is minimized by the use of a low level of oxygen fed to the reactor as air or other oxygen-containing gas. The raw material is chloroolefin. Chloroolefins are vulnerable to polymerization that can cause catalyst deactivation. Coalimentation of a low level of a polymerization inhibitor, such as p-methoxyphenol, can control said polymerization and extend the life of the catalyst as described in U.S. Pat. No. 5,714,651, incorporated herein by reference. The presence of a low level of a polymerization inhibitor such as p-methoxyphenol can inhibit the polymerization of chloroolefins such as 1,1-dichloroethylene. The process of the present invention is directed to the preparation of fluorination products of the formula CF3R, where R is selected from -CCl = CH2, -CF = CH2, -CF2-CH3, -CFCl-CHa, -CHF-CH2F and mixtures in these.

The process of the present invention can be summarized with the following scheme:

image 1

Fluoridation of the gas phase of 1230xa

The process comprises contacting 1230xa, optionally with a polymerization inhibitor, with HF in the gas phase in the presence of a chromium-based catalyst, supported or unsupported, to obtain the desired product 1234yf. The chromium-based catalyst, supported or unsupported, of the present invention is activated by contact with Hf at high pressure which is a pressure greater than 10.34 bar (150 psi). The chromium-based catalyst may optionally include one or more cocatalysts selected from cobalt, nickel, zinc and manganese. An oxidizing agent containing oxygen is fed to the reactor to maintain the activity of the catalyst. Oxygen can be fed as a pure gas or as an oxygen-containing gas, such as air. A polymerization inhibitor can also be fed to the reactor to maintain catalyst activity. Co-products produced by the fluorination reaction such as F245cb (CF3-CF2-CH3), F1233xf (CF3-CCl = CH2), F244bb (CF3-CFCl-CH3), 245eb (CF3-CHF-CH2F) and unreacted material such as HF and F1230xa it can be recycled to the same reactor. The process can be carried out through a continuous or batch process. The desired product 1234yf is known to have utility as a foaming agent, refrigerant, aerosol propellant, heat transfer media, fire extinguisher etc. In addition, the 1234yf product is known to have zero ozone depletion power (ODP) and very low global warming potential (GWP) of much less than 150, low flammability and non-toxic.

Detailed description of the invention

The process of the present invention comprises the gas phase, catalyzed fluorination of 1230x. The catalyst is a chromium-based catalyst that may optionally contain low levels of one or more cocatalysts selected from cobalt, nickel, zinc or manganese, prepared by processes known in the art, such as impregnation, mixed powder. The catalyst can be supported or unsupported. For the supported catalyst, the catalyst support can be selected from materials known in the art that are compatible with Hf at higher temperature and pressure. For example, fluorinated alumina, pre-fluorinated activated carbon, graphite or fluorinated graphite are suitable catalyst supports. A preferred catalyst is an unsupported chromium oxide catalyst of large surface area. The catalyst is activated before use. Catalyst activation comprises

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a high pressure process, greater than 10.34 bar (150 psi), in which the catalyst bed is heated to approximately 370-380 ° C, preferably with a continuous flow of nitrogen, after which approximately volumes are mixed Equals of HF and air or nitrogen (preferably nitrogen) are fed onto the catalyst bed. The catalyst activation process is as described in U.S. Pat. No. 7,485,598.

Other fluorinated organic compounds such as CHF2Cl, CHF3, CF3CH2F, CF3CH2O and the like can be used for activation. Typically, the high pressure catalyst activation procedure takes approximately 18 hours.

The resulting high pressure activated catalyst has a high surface area, such as from about 20 to about 250 square meters per gram. The fluorine content varies between approximately 20 to 25% by weight. The pore volume has an average value between 0.1 to 0.4 m3 / g. The compressive strength is between 20 and 30 lb / gm. The percentage of attrition is on average between 1 to 5% by weight and the Cr (vi) level should be in the range of 100 to 300 ppm. The level of the cocatalyst, when present, can vary between 1 and 10% by weight, preferably between 1 and 5% by weight. The cocatalyst can be added to the catalyst by processes known in the art, such as adsorption from an aqueous or organic solution, followed by evaporation of the solvent. A preferred catalyst is pure chromium oxide with nickel as cocatalyst. Alternatively, the cocatalyst can be physically mixed with the catalyst by grinding to produce an intimate mixture. An alternative catalyst is a mixed chromium / nickel catalyst supported on fluorinated alumina. U.S. Patent No. 5,731,481, describes a method of preparing this alternative catalyst that can be activated as described above.

It has been found that chromium-based catalysts, activated through the high pressure process described above, are useful for fluorinating 1230xa in a catalyzed gas phase fluoridation process to produce the desired product, 1234yf, with high conversion of 1230xa. The 1230xa fluorination process involves contacting 1230xa, preferably inhibited with a polymerization inhibitor, with HF in the reaction zone in a gas phase, under conditions sufficient to convert the 1230xa into fluorination products such as CF3R, where R is selected of -CCl = CH2-CF = CH2, -CF2-CH3, -CFCECH3, -CHF CH2F and mixtures thereof, HF and HCl. The molar ratio of HF: 1230xa is typically from about 2: 1 to 50: 1, but is preferably from about 5: 1 to about 30: 1. The catalyst bed temperatures may vary from about 30 ° C to about 410 ° C and are preferably from about 100 ° C to about 350 ° C. The pressures are typically from about atmospheric to about 27.58 bar (400 psig), preferably from about 1.38 to about 20.68 bar (from 20 to 300 psig). An oxygen coalimentation is used to extend the life of the catalyst, typically in an amount of about 0.005 to about 3% moles of oxygen per 1230xa. Oxygen can be introduced as an oxygen-containing gas, such as air, pure oxygen or an oxygen / nitrogen mixture. A polymerization inhibitor can be used to extend the life of the catalyst, typically in a concentration of about 50-1000 ppm, more preferably between 100-500 ppm. The polymerization inhibitor may be p-methoxyphenol, t-amylphenol, limonene, d, 1-limonene, quinones, hydroquinones, epoxides, amines and mixtures thereof. The preferred polymerization inhibitor is p-methoxyphenol or t-amylphenol.

The contact times (catalyst volume divided by the total flow rate of the reagents and the co-feeds, adjusted to the operating pressure and temperature) are preferably from about 1 to about 500 seconds, more preferably from about 1 to about 180 seconds .

The desired product, 1234yf, can be separated from the other co-produced products present in the reaction mixture by means known in the art such as distillation (including extractive distillation) or adsorption. A preferred method of separating the preferred product comprises extracting HCl from the reaction mixture leaving the reactor in a distillation column. Subsequently, in a second distillation zone, the product of lower boiling point 1234yf can be separated from unreacted products such as HF and F1230xa, intermediate compounds such as F1233xf and 244bb and co-products such as F245cb and 245eb, all of these latter recycled to the reactor of the single reactor process This second distillation zone can use single or multi stage distillation. As used herein, the percentage is in percent by weight, unless otherwise specified.

Example 1. High pressure activation of Cr2O3 catalyst

A Cr2O3 catalyst was activated at 16.20 bar (235 psig) and 350 ° C using HF and nitrogen gas. The chemical and physical properties of the resulting catalyst are shown in Table 1.

Table 1. Summary of the physical and chemical properties of the high pressure activated catalyst

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 % F content

 22.2% (weight)

 Superficial area

 43.9

 m2 / g1

 Pore volume m3 / g2

 0.19

 Compressive strength

 23.30

 lb3

 Crnivel + 6

 201.00 ppm

 % Attrition4

 3.9

1. The surface area was determined by the BET surface area by Micrometrics ASAP 2400

2. The pore volume was evaluated using the xylene porosity measurement.

3. Compressive strength was evaluated by applying a specific compression rate, until the integrity of the catalyst is compromised.

4. The percentage of attrition was evaluated by using the standard test method ASTM D-4058-92 for attrition

Examples 2-3 1230x fluorination using high pressure activated catalyst, in the presence of the polymerization inhibitor

A catalyst, obtained from Example 1 (52.4 grams, density 1.22 g / cc) can be placed in a 1 "x 12 vertical fixed bed reactor made of Hastelloy C. The reactor can be heated using a three zone electric tube furnace The reactor inlet fittings can include inputs for HF gas, organic feed (1230xa) and air.The liquid HF feed can be measured and controlled using a liquid mass flow meter controller. Liquid HF can be vaporized using a preheater before feeding the reactor.The organic compound (1230xa, which contains p-methoxyphenol 200 ppm) can be fed using a high pressure ISCO pump.The air supply can be controlled and measured using controllers of the gas mass flow meter The molar ratio of HF to 1230x can vary from 20/1 to 30/1 in the presence of oxygen (3% by volume). The reagents can be fed to the reactor at 330 ° C. can be adjusted r at 10.34 bar (150 psig), using a downstream regulator. The reaction products can be continuously removed from the reactor. After washing the acid with a 15% KOH solution and drying the organic products, using a bed of anhydrous CaSO4, the dried organic product can be analyzed, using GC. Table 2 summarizes the expected results of the gas chromatographic analysis of the products. The increase in the molar ratio from 20/1 to 30/1 is expected to show an increase in the level of 1234yf and 245cb produced, with a decrease in 1233xf produced. Table 2 summarizes the expected results.

Table 2. Gaseous phase fluoridation of a stage from 1230x to 1234yf

Catalyst, Cr2O3 activated at high pressure, oxygen 0.5% by volume, p-methoxyphenol 200 ppm

 Example

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 Temperature (° C)

 330 330

 Pressure (bar)

 10.34 (150 psi) 10.34 (150 psi)

 Contact time (sec)

 28 19

 Molar Ratio (HF / 1230xa)

 1/1 30/1

 O2 feed (% by weight)

 0.5 0.5

 % Conversion

 100 100

 1234yf

 11.5 15.5

 245cb

 20.7 31.2

 Example

 2. 3

 1233xf

 66.6 51.5

 244bb

 0.7 0.5

 245eb

 0.1 0.4

 others

 0.4 0.9

1234yf is CFaCF = C ^; 245cb is CF3CF2CH3; 1233xf is CFaCCl = C ^; 244bb is CF3CFCICH3; 245eb is CF3 CHF CH2F

5 Example 4 Fluoridation of 1230x in the absence of oxygen coalimentation and in the presence of a polymerization inhibitor

The process described in Example 2 can be carried out in the absence of oxygen carbonation in the presence of the polymerization inhibitor, 200 ppm of p-methoxyphenol. Conversion can be expected to decrease from a maximum of about 99% to less than 50% after continuously operating 10 for 100 hours due to catalyst deactivation. The product and co-distribution can be expected to be similar to the selectivity described in Table 2.

Example 5 Fluoridation of 1230x, in the absence of the polymerization inhibitor, and in the presence of the oxygen coalimentation.

The fluorination of 1230x can be repeated as in Example 4. Polymerization inhibitor 15 cannot be added and oxygen oxygenation can be 0.5% by volume. In this case, the conversion can be expected to decrease from approximately 99% to less than 50% in approximately 18 hours. The level of co-products identified as fluorinated ketones can be expected to increase to approximately 0.5%.

Example 6 - 7 Fluoridation of 1230xa with 1233xf, 244bb, 245cb and 245eb

The process described in Examples 2 and 3 can be repeated with a feed of 1230x to 76% by weight, in combination with infrafluorinated materials 1233xf 8% by weight, 244bb 6% by weight, 245cb 4% by weight and 245eb 6% by weight. weight using the catalyst and the processing conditions, described in Example 2 and 3. Table 3 summarizes the expected results

Table 3

 Example

 6 7

 T C

 330 330

 P (bar)

 10.34 (150 psi) 10.34 (150 psi)

 CT sec

 28 19

 MR HF / organic

 20/1 30/1

 02%

 3% 3%

 %Conversion

 100 100

 1234yf

 18.5 20.5

 245cb

 8.5 11.5

 1233xf

 56 52

 244bb

 15.5 13.5

 245eb

 1 1.6

 others

 0.5 0.8

Claims (15)

5 10 fifteen twenty 25 30 35 40 1. A process for preparing 2,3,3,3-tetrafluoropropene, which comprises contacting 1,1,2,3-tetrachloropropene with hydrogen fluoride in the gas phase in the presence of a chromium fluorination catalyst, and an oxygen-containing oxidizing agent that is pure oxygen gas or oxygen-containing gas, said oxidizing agent which is in an amount of 0.005 to 3% in mol of oxygen relative to 1,1,2,3-tetrachloropropene, under conditions sufficient to directly produce, in a single reactor, a reaction mixture comprising 2,3,3, 3-tetrafluoropropene and at least one compound of formula CF3R, where R is selected from -CCl = CH2, -CF2-CH3, -CFClCH3 and CHF-CH2F; removing the HCl from said reaction mixture; separating 2,3,3,3-tetrafluoropropene from said reaction mixture; Y recycle the hydrogen fluoride from the reactor, at least one compound of formula CF3R, where R is selected from -CCl = CH2, -CF2-CH3, -CFClCH3 and -CHF CH2F wherein said fluorination catalyst is activated with hydrogen fluoride at a pressure greater than 10.34 bar (150 psi). 2. The process of claim 1 wherein said chromium fluorination catalyst is supported or unsupported. 3. The process of claim 2 wherein said chromium fluorination catalyst is supported on a support selected from fluorinated alumina, fluorinated chromium, activated carbon or fluorinated graphite carbon. 4. The process of claim 1 wherein said chromium fluorination catalyst further comprises a cocatalyst selected from Ni, Co, Zn, Mn or mixtures thereof. 5. The process of claim 1 wherein said 1,1,2,3-tetrachloropropene includes a polymerization inhibitor. 6. The process of claim 5 wherein said polymerization inhibitor is selected from the group consisting of p-methoxyphenol, t-amylphenol, limonene, d, 1-limonene, quinones, hydroquinones, epoxides, amines and mixtures thereof. same. 7. The process of claim 4 wherein said cocatalyst is present in an amount of 1-10% by weight of said fluorination catalyst. 8. The process of claim 1 wherein said chromium fluorination catalyst comprises chromium catalyst supported with nickel cocatalyst. 9. The process of claim 1 wherein said oxidizing agent is selected from air or oxygen. 10. The process of claim 9 wherein said oxidizing agent is added in an amount of 0.05 to 1% in mol of oxygen relative to 1230xa. 11. The process of claim 1 wherein said separation is by means of one or more distillation operations. 12. The process of claim 1 wherein the molar ratio of HF to 1230x is 2: 1 to 50: 1, preferably 5: 1 to 30: 1. 13. The process of claim 1 wherein the temperature of the chromium fluorination catalyst ranges from 30 ° C to 410 ° C, preferably from 100 ° C to 350 ° C. 14. The process of claim 1 wherein the pressure varies from atmospheric pressure to 27.58 bar (400 psig), preferably from 1.38 to 20.68 bar (from 20 psig to 300 psig). 15. The process of claim 1 wherein said contact is a continuous operation.