Chromium based catalyst for dehydrofluorination, and preparation method and application thereof

Abstract

The invention discloses a chromium based catalyst ford ehydrofluorination. The catalyst contains 15mol%-95mol% of chromium and 5mol%-85mol% of an active metal, and the active metal is a combination of one, two or three selected from the group consisting of aluminum, zinc, magnesium, cobalt, nickel, iron and copper. The catalyst provided by the invention can be used for vinyl fluoride preparation through 1,1-difluoroethane cracking; and the catalyst has the advantages of simple preparation process, low cost of raw materials and high reaction activity and stability.

Description

technical field

[0001] The invention relates to a chromium-based catalyst, in particular to a chromium-based catalyst for dehydrofluorination and a preparation method thereof. Background technique

[0002] Vinyl fluoride (VF) is an important fluorine-containing monomer, which is mainly used in the preparation of polyvinyl fluoride (PVF). PVF is the one with the lowest fluorine content and the smallest density among fluororesins. It has excellent chemical corrosion resistance, hydrophobicity, abrasion resistance, aging resistance and non-stickiness. It has been widely used in the protective layer of building materials, Encapsulation of aviation industry and solar cells, inner wall coating of packaging containers, anticorrosion of oil pipelines in oil fields, etc.

[0003] The prior art discloses a variety of VF monomer preparation routes, among which the production technology using acetylene and HF as raw materials is relatively mature, but there are problems such as short c...

Examples

Embodiment 1

[0028] Cr(NO 3 ) 3 9H 2 O is dissolved in a certain amount of water, and ammonia water is added as a precipitating agent under stirring, and the pH of the solution is adjusted to 9.0, so that the dissolved Cr 3+ It can be fully precipitated, and the formed slurry is filtered, washed, and dried at 110°C for 24 hours to obtain Cr(OH) 3 . The obtained Cr(OH) 3 It is ball-milled and mixed with MgO according to the mole percentages of Cr and Mg to be 50 mol % and 50 mol %, and pressed into tablets to obtain a catalyst precursor.

[0029] Put the catalyst precursor into a ф14*1000 carbon steel reaction tube, 2 Calcined at 300°C for 6 hours under the atmosphere, and introduced volume ratio HF:N 2 The mixed gas of 1:4 is fluorinated at 250°C for 2h, then the temperature is raised to 360°C at a rate of 1°C / min, and the fluorination is continued for 12h, and then fluorinated with pure HF for 4h to obtain a chromium-based catalyst.

[0030] The prepared chromium-based catalyst is ...

Embodiment 2

[0034] Chromium-based catalysts are prepared according to the method described in Example 1, but Cr(OH) 3 The mole percentage composition with MgO is adjusted to 30 mol% and 70 mol% to obtain the chromium-based catalyst of the present invention.

[0035] The prepared chromium-based catalyst was used in the dehydrofluorination reaction of 1,1-difluoroethane, and the reaction temperature was controlled at 350°C and the space velocity was 500h -1 , The conversion rate of 1,1-difluoroethane and the selectivity of vinyl fluoride are shown in Table 2.

[0036] Table 2

[0037] Reaction time

[0038] (h)

Embodiment 3

[0040] KCr(SO 4 ) 2 12H 2 O is dissolved in a certain amount of water, and ammonia water is added as a precipitating agent under stirring, and the pH of the solution is adjusted to 8.5, so that the dissolved Cr 3+ It can be fully precipitated, and the formed slurry is filtered, washed, and dried at 150°C for 24 hours to obtain Cr(OH) 3 . The obtained Cr(OH) 3 with AlF 3 The mole percentages of Cr and Al are divided into 75 mol % and 25 mol % for ball milling and mixing, and tablet molding to obtain a catalyst precursor.

[0041] Put the catalyst precursor into a ф14*1000 carbon steel reaction tube, 2 Calcined at 400°C for 6 hours under the atmosphere, and introduced volume ratio HF:N 2 The 1:2 mixed gas is fluorinated at 250°C for 2 hours, then the temperature is raised to 360°C at a rate of 1°C / min, the fluorination is continued for 12 hours, and then pure HF is passed through for fluorination for 4 hours to obtain the chromium-based catalyst.

[0042] The prepared c...

technical field

[0001] The invention relates to a chromium-based catalyst, in particular to a chromium-based catalyst for dehydrofluorination and a preparation method thereof. Background technique

[0002] Vinyl fluoride (VF) is an important fluorine-containing monomer, which is mainly used in the preparation of polyvinyl fluoride (PVF). PVF is the one with the lowest fluorine content and the smallest density among fluororesins. It has excellent chemical corrosion resistance, hydrophobicity, abrasion resistance, aging resistance and non-stickiness. It has been widely used in the protective layer of building materials, Encapsulation of aviation industry and solar cells, inner wall coating of packaging containers, anticorrosion of oil pipelines in oil fields, etc.

[0003] The prior art discloses a variety of VF monomer preparation routes, among which the production technology using acetylene and HF as raw materials is relatively mature, but there are problems such as short c...

Examples

Embodiment 1

[0028] Cr(NO 3 ) 3 9H 2 O is dissolved in a certain amount of water, and ammonia water is added as a precipitating agent under stirring, and the pH of the solution is adjusted to 9.0, so that the dissolved Cr 3+ It can be fully precipitated, and the formed slurry is filtered, washed, and dried at 110°C for 24 hours to obtain Cr(OH) 3 . The obtained Cr(OH) 3 It is ball-milled and mixed with MgO according to the mole percentages of Cr and Mg to be 50 mol % and 50 mol %, and pressed into tablets to obtain a catalyst precursor.

[0029] Put the catalyst precursor into a ф14*1000 carbon steel reaction tube, 2 Calcined at 300°C for 6 hours under the atmosphere, and introduced volume ratio HF:N 2 The mixed gas of 1:4 is fluorinated at 250°C for 2h, then the temperature is raised to 360°C at a rate of 1°C / min, and the fluorination is continued for 12h, and then fluorinated with pure HF for 4h to obtain a chromium-based catalyst.

[0030] The prepared chromium-based catalyst is ...

Embodiment 2

[0034] Chromium-based catalysts are prepared according to the method described in Example 1, but Cr(OH) 3 The mole percentage composition with MgO is adjusted to 30 mol% and 70 mol% to obtain the chromium-based catalyst of the present invention.

[0035] The prepared chromium-based catalyst was used in the dehydrofluorination reaction of 1,1-difluoroethane, and the reaction temperature was controlled at 350°C and the space velocity was 500h -1 , The conversion rate of 1,1-difluoroethane and the selectivity of vinyl fluoride are shown in Table 2.

[0036] Table 2

[0037] Reaction time

[0038] (h)

Embodiment 3

[0040] KCr(SO 4 ) 2 12H 2 O is dissolved in a certain amount of water, and ammonia water is added as a precipitating agent under stirring, and the pH of the solution is adjusted to 8.5, so that the dissolved Cr 3+ It can be fully precipitated, and the formed slurry is filtered, washed, and dried at 150°C for 24 hours to obtain Cr(OH) 3 . The obtained Cr(OH) 3 with AlF 3 The mole percentages of Cr and Al are divided into 75 mol % and 25 mol % for ball milling and mixing, and tablet molding to obtain a catalyst precursor.

[0041] Put the catalyst precursor into a ф14*1000 carbon steel reaction tube, 2 Calcined at 400°C for 6 hours under the atmosphere, and introduced volume ratio HF:N 2 The 1:2 mixed gas is fluorinated at 250°C for 2 hours, then the temperature is raised to 360°C at a rate of 1°C / min, the fluorination is continued for 12 hours, and then pure HF is passed through for fluorination for 4 hours to obtain the chromium-based catalyst.

[0042] The prepared c...

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