CN1954911A - Solid catalyst and its preparation and method of catalytic preparation epoxy propane hexafluoride - Google Patents

Abstract

The catalyst used to produce hexafluoropropylene oxide by the gas phase method is an Ag-based catalyst, and the composition of the catalyst is: Ag 10-50%, alkali metal or alkaline earth metal compound 1-20% and carrier 49-89% . The solid catalyst is used to catalyze the preparation of hexafluoropropylene oxide, which is to let the mixed gas of hexafluoropropylene and molecular oxygen pass through the prepared catalyst layer at a reaction temperature of 80-170°C and a reaction pressure of 0.1-5Mpa in a tubular reactor. Preparation of hexafluoropropylene oxide. The conversion rate of hexafluoropropylene oxide can reach 40-80%, and the selectivity can reach 40-90%.

Description

A kind of solid catalyst and its preparation and catalytic method for preparing hexafluoropropylene oxide

technical field

The invention relates to a solid catalyst and a method for preparing hexafluoropropylene oxide by catalyzing the same. The catalyst is used for preparing hexafluoropropylene oxide by taking hexafluoropropylene and molecular oxygen as starting materials to undergo catalytic oxidation reaction in a reactor.

Background technique

Hexafluoropropylene oxide C ₃ F ₆ O, also known as perfluoropropylene oxide, is a synthetic perfluorinated ion exchange resin, perfluoroplastic, perfluororubber, perfluorinated lubricating oil, perfluorinated heat-resistant medium, and fluorosurfactant , solvents and other important intermediates of organic fluorine materials. Known oxidation hexafluoropropylene is prepared the oxidizing agent used of hexafluoropropylene oxide mainly to be: hydrogen peroxide (US3358003,1967; US 3250808,1966; JP 63027487,1988); Hypochlorite (US 4902810,1990); Peroxide (GB 1547493, 1979); Carbonate (US 4287128, 1981); Molecular oxygen (US 3536733, 1970; CN 1320598, 2001; JP 9052886, 1997), etc. Using hydrogen peroxide as an oxidant, because hydrogen peroxide itself is expensive, transportation and storage are very troublesome, the production cost of hexafluoropropylene oxide will be increased, and a large amount of waste water will also be generated, causing environmental pollution. Using hypochlorite will also produce a large amount of waste water, which is not good for the environment. Organic peroxides are not suitable for industrial applications due to price and environmental considerations. When carbonate is used as an oxidant, a large amount of chlorine gas is used as a reactant, which increases the production cost and is not conducive to environmental protection. Molecular oxygen is the most economical and environmentally friendly oxidant among all oxidants.

The reported methods for preparing hexafluoropropylene oxide in the liquid phase oxidation of hexafluoropropylene with molecular oxygen are in the presence of an inert solvent (GB 1034492, 1966; US 3536733, 1970; JP 2003040879, 2003) or in the presence of an initiator in an inert (CN 1320598,2001) reaction in solvent to prepare hexafluoropropylene oxide. In these methods, the process is relatively complicated, and the use of organic solvents or initiators will cause certain environmental problems. In addition, the conversion rate and selectivity are not high, and it must undergo complicated post-treatment processes such as separation, and the production cost is relatively high.

Hexafluoropropylene and molecular oxygen can be reacted in gas phase in the presence of solid catalyst to prepare hexafluoropropylene oxide. The catalyst used in the method for preparing hexafluoropropylene oxide in the reported molecular oxygen phase catalytic oxidation of hexafluoropropylene has: 1. use a barium compound as a catalyst, and the barium compound can be barium oxide, barium hydroxide or barium salt, and the barium salt is Inorganic salts are preferred, such as barium fluoride, barium chloride, barium sulfate, barium carbonate, barium nitrate, etc. (US 4288376, 1981). Hexafluoropropylene oxide is prepared by passing hexafluoropropylene and molecular oxygen through a fixed-bed or fluidized-bed reactor with a barium compound. The conversion rate of hexafluoropropylene is 24.2-34.1%, and the corresponding selectivity of hexafluoropropylene oxide is 67.4-70.1%. ② Silica gel or SiO ₂ compound is used as a catalyst, and hexafluoropropylene and molecular oxygen are passed through a fixed bed or fluidized bed reactor containing the activated catalyst for catalytic oxidation to prepare hexafluoropropylene oxide. The conversion rate of hexafluoropropylene is 10-40%, and the selectivity of hexafluoropropylene oxide is about 80% (US 3775438, 1973, US 3775439, 1973). The preparation of hexafluoropropylene oxide by phase catalytic oxidation of hexafluoropropylene and molecular oxygen is a very promising production method for hexafluoropropylene oxide. The key is to prepare hexafluoropropylene oxide with high conversion rate of hexafluoropropylene. Highly selective catalyst. Catalysts in the prior art catalyze the preparation of hexafluoropropylene oxide. The conversion rate of hexafluoropropylene is too low, which will inevitably bring complicated post-treatment processes. If the conversion rate of hexafluoropropylene is increased, the selection of hexafluoropropylene oxide will be caused. The performance is reduced, so that it brings difficulties to industrial applications.

Contents of the invention

The technical problem to be solved by the present invention is to prepare a catalyst suitable for preparing hexafluoropropylene oxide by catalytic oxidation of hexafluoropropylene and molecular oxygen as starting materials and its preparation method, so that hexafluoropropylene can However, it still has high selectivity. The invention also provides a method for preparing hexafluoropropylene oxide catalyzed by the catalyst.

The solid catalyst provided by the present invention is used to produce hexafluoropropylene oxide by the gas phase method, and is characterized in that it is an Ag-based catalyst. In terms of mass percentage, the composition of the catalyst is: Ag 10-50%, alkali metal or alkaline earth metal compound 1 ~20% and vehicle 49-89%.

The alkali metal or alkaline earth metal compound refers to oxides, fluorides, chlorides, sulfates, carbonates, nitrates or hydroxides of alkali metals or alkaline earth metals. The alkali metal is preferably potassium or cesium, and the alkaline earth metal is preferably calcium or barium.

The carrier can be one or more of SiO ₂ , ZrO ₂ , TiO ₂ , CaCO ₃ or α-Al ₂ O ₃ .

The preparation method of the above-mentioned catalyst is as follows: mixing the carrier with an alkali metal or alkaline earth metal compound, grinding, molding (can be in various shapes, such as granular, flake, etc.), screening 20-200 mesh particles, and then adding to the pre-prepared The silver solution is stirred and dispersed by ultrasound to form a uniform slurry, dried at 80-120°C for 1-12 hours, and then calcined at 250-500°C for 1-6 hours.

The active component silver forms a silver solution, which can be a silver nitrate solution, or a silver ammonium complex solution formed by the reaction of silver oxide, oxalic acid and ethylenediamine.

The catalyst formed after calcining is granulated and screened, and the diameter of the catalyst particles is 20-200 mesh, preferably 20-60 mesh.

The above prepared solid catalyst catalyzes the method for preparing hexafluoropropylene oxide, which is to allow hexafluoropropylene and molecular oxygen (which can be pure oxygen, The mixed gas of air or oxygen and nitrogen, helium or carbon dioxide) passes through the prepared catalyst layer to prepare hexafluoropropylene oxide.

This reaction is an exothermic reaction, and the reaction is carried out in a tubular reactor. The preferred total length of the tubular reactor is 1 to 100 meters. If it is too long, it will cause over-reaction and increase the by-products; if it is too short, the reaction will be incomplete. . The tubular reactor is a serpentine reactor.

The catalyst provided by the invention enables the conversion rate of the hexafluoropropylene oxide to reach 40-80%, and the selectivity to reach 40-90%. At the same time, the continuous production of the product can be realized, thereby realizing the transformation of the currently widely used batch reaction method to continuous production.

Description of drawings

Figure 1 is a schematic diagram of the tubular reactor structure.

In the figure: 1 tube reactor 2 material inlet 3 material outlet 4 media inlet 5 media outlet 6 media tank

Detailed ways

As shown in Fig. 1, the catalyst is loaded in the tubular reactor 1, and hexafluoropropylene and molecular oxygen gas undergo a catalytic oxidation reaction through the catalyst layer to prepare hexafluoropropylene oxide.

Tubular reactor 1 is a segmented serpentine reactor, which is divided into two parts: straight pipe section and curved pipe section. The straight pipe section is used for loading catalyst, and the curved pipe section is a gas phase buffer part, which is not filled with catalyst. The lower part of each straight pipe section will be provided with a support plate, which is used as a catalyst for carrying (known technology). The total length of the tubular reactor is 1-100 meters, and the inner diameter is 1-200 mm, which is placed vertically.

A material inlet 2 and a material outlet 3 are respectively set at both ends of the tubular reactor, and 1-2 sampling ports are set in the middle.

The serpentine tube reactor is set in a media tank 6, which is provided with a media inlet 4 and a media outlet 5 for cold or hot media to enter and exit, and has the function of heating or cooling.

Specific implementation examples are given below to further illustrate the present invention.

Example 1

Weigh 2g of oxalic acid and dissolve it in 5ml of water, then mix it with 5ml of ethylenediamine, add 3.5g of silver oxide under full stirring, and continue stirring to dissolve it to form a silver ammonium complex solution. Weigh 3g of SiO ₂ , fully mix and grind with 0.5g BaF, then granulate, screen 20-200 (preferably 20-60) mesh particles, add them to the above solution, and mix for 1 hour under stirring and ultrasonication simultaneously. Uniform slurry. After drying in an oven at 100°C for 5 hours, calcining in a muffle furnace at 450°C for 6 hours, granulating after natural cooling, and sieving to get 20-200 mesh (preferably 20-60 mesh) particles. The composition of this catalyst is:

Ag 30%

BaF 10%

SiO ₂ 60%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 135°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The yield was 50.2%, and the selectivity of hexafluoropropylene oxide was 59.6%.

Example 2

The preparation method is the same as in Example 1, except that BaF is changed to BaCl ₂ . The composition of the catalyst is:

Ag 30%

_BaCl2 10%

SiO ₂ 60%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 120°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The yield was 51.3%, and the selectivity of hexafluoropropylene oxide was 70.2%.

Example 3

The preparation method is the same as in Example 1, except that BaF is changed to CsCl. The catalyst consists of:

Ag 30%

CsCl 10%

SiO ₂ 60%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 135°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The yield was 40.3%, and the selectivity of hexafluoropropylene oxide was 48.2%.

Example 4

Preparation method is with embodiment 1, and catalyst composition changes into:

Ag 20%

BaF 15%

SiO2 65%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 130°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The yield was 45.1%, and the selectivity of hexafluoropropylene oxide was 44.6%.

Example 5

Weigh 3g of SiO ₂ , thoroughly mix and grind with 0.5g BaF, then granulate, and screen the 20-60 mesh particles. Add it into a solution made of 4.97g of silver nitrate and 5ml of deionized water, stir and ultrasonically disperse for 1 hour. Then put it in an oven and bake at 100°C for 6 hours, take it out and put it in a muffle furnace for calcination at 450°C for 6 hours. Granulate after natural cooling, and sieve to get 20-60 mesh particles. The catalyst composition is as follows:

Ag 30%

BaF 10%

SiO ₂ 60%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 115°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The rate is 40.3%, and the selectivity of hexafluoropropylene oxide is 63.6%.

Example 6

The preparation method is the same as in Example 5, except that BaF is changed to BaCl ₂ . The composition of the catalyst is:

Ag 30%

_BaCl2 10%

SiO ₂ 60%

The catalyst of this composition is used in the catalytic oxidation of hexafluoropropylene and molecular oxygen to prepare hexafluoropropylene oxide, the reaction temperature is 110 ° C, the reaction pressure is 2.5Mpa, the result is: the conversion rate of hexafluoropropylene is 40.3%, six The selectivity of fluoropropylene oxide is 69.2%.

Example 7

The preparation method is the same as in Example 1, except that BaF is changed into KCl. The catalyst consists of:

Ag 30%

KCl 10%

SiO ₂ 60%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 125°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The yield was 55.3%, and the selectivity of hexafluoropropylene oxide was 48.2%.

Example 8

The preparation method is the same as in Example 5, changing BaF to CsCl. The catalyst composition is adjusted accordingly:

                               

CsCl 5%

SiO2 85%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 125°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The rate is 55%, and the selectivity of hexafluoropropylene oxide is 45%.

Example 9

The preparation method is the same as in Example 5, changing BaF to CaF. The catalyst composition is adjusted accordingly:

Ag 40%

CaF 3%

SiO ₂ 57%

Put the catalyst of this composition in a tubular reactor, maintain the reaction temperature at 125°C, feed hexafluoropropylene and molecular oxygen, the molar ratio is 1:0.5, and the reaction pressure is 2.5Mpa, the result is: the conversion of hexafluoropropylene The rate is 55%, and the selectivity of hexafluoropropylene oxide is 47%.

Claims (10)

1. A solid catalyst for the production of hexafluoropropylene oxide by a gas phase method, characterized in that it is an Ag-based catalyst, and the composition of the catalyst is: Ag10-50%, alkali metal or alkaline earth metal compound 1-20% by mass percentage % and carrier 49-89%. 2. The catalyst according to claim 1, characterized in that the alkali metal or alkaline earth metal compound refers to oxides, fluorides, chlorides, sulfates, carbonates, nitrates or hydroxides of alkali metals or alkaline earth metals thing. 3. The catalyst according to claim 1, characterized in that the alkali metal is potassium or cesium, and the alkaline earth metal is calcium or barium. 4. The catalyst according to claim 1, characterized in that the carrier is one or more of SiO ₂ , ZrO ₂ , TiO ₂ , CaCO ₃ or α-Al ₂ O ₃ . 5. A method for preparing a solid catalyst as claimed in any one of claims 1 to 4, characterized in that the carrier is mixed with an alkali metal or alkaline earth metal compound, ground, and shaped, and the particles of 20 to 200 meshes are screened, and then added to the pre-prepared The silver solution is stirred to form a uniform slurry, then dried at 80-120°C for 1-12 hours, and then calcined at 250-500°C for 1-6 hours. 6. The preparation method according to claim 5, characterized in that the silver solution is a silver nitrate solution. 7. The preparation method according to claim 5, characterized in that the silver solution is a silver ammonium complex solution formed by the reaction of silver oxide, oxalic acid and ethylenediamine. 8. The preparation method according to claim 5, characterized in that the calcined catalyst is granulated and sieved, and the diameter of the catalyst particles is 20-200 mesh. 9. A method for preparing hexafluoropropylene oxide catalyzed by the solid catalyst according to any one of claims 1 to 4, characterized in that the reaction temperature is 80-170°C and the reaction pressure is 0.1-5Mpa in the tubular reactor. The mixed gas of hexafluoropropylene and molecular oxygen passes through the prepared catalyst layer to prepare hexafluoropropylene oxide. 10. The method for catalytically preparing hexafluoropropylene oxide according to claim 9, characterized in that the tubular reactor is in the shape of a snake with a length of 1-100 meters.