Preparation method of 1,1-difluoroethylene

Abstract

The invention provides a preparation method of 1,1-difluoroethylene. The 1,1-difluoroethylene is generated by virtue of gas phase dehydrochlorination on 1,1-dichloro-1-chloroethane (HCFC-142b) under the action of a catalyst, wherein the catalyst is composed of a main catalyst and an auxiliary catalyst; the main catalyst is a Ba-based catalyst and the auxiliary catalyst is a transitional metal and lanthanide series metal fluoride. The preparation method of 1,1-difluoroethylene provided by the invention has the characteristics of being high in yield, is unlikely to block pipelines, mild in conditions of preparation process, simple to operate, high in selectivity of products and the like.

Description

technical field

[0001] The invention belongs to the technical field of preparation of chlorofluoroolefins, and in particular relates to a preparation method of 1,1-difluoroethylene. The method prepares 1,1-difluoroethylene through catalytic dehydrochlorination. Background technique

[0002] 1,1-Difluoroethylene (vinylidene fluoride) is one of the important varieties of fluorine-containing olefins, mainly used in the production of poly-1,1-difluoroethylene resin, fluororubber and fluorine-containing copolymers such as 1,1-difluoroethylene Fluoroethylene-hexafluoropropylene, 1,1-difluoroethylene-1,1-difluoroethylene, 1,1-difluoroethylene-tetrafluoroethylene-hexafluoropropylene, etc. In addition, the fluorine rubber obtained by the copolymerization of 1,1-difluoroethylene, hexafluoropropylene and tetrafluoroethylene has become an indispensable product in modern industry, especially in high-tech fields, because of its excellent high temperature resistance, oil resistance, solven...

Examples

Embodiment 1

[0027] Barium hydroxide is placed in a roasting furnace at 800 ° C for 4 hours to obtain a barium oxide catalyst,

[0028] The obtained barium oxide catalyst is then used to catalyze the removal of HCl from 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tubular reactor. The reaction tube of the tubular reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up and the temperature is raised to 400°C for reaction. The reaction pressure At normal pressure, before the reaction, N 2 (with an airspeed of 1000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200°C at a rate of 5°C / min and dried for 2 h, then raised to 400°C at a rate of 5°C / min and then cooled to 200°C after catalyst treatment for 2 h. HCFC-142b continued to process for another 2 hours. After heating up to 400°C, pass HCFC-142b and N 2 The mixed gas undergoes a gas-...

Embodiment 2-6

[0030] Barium hydroxide is placed in a roasting furnace at 800 ° C for 4 h to obtain a barium oxide catalyst, and 5 wt % of CoF 3 、NiF 2 、CuF 2 、LaF 3 , CeF 3 Mix with barium oxide in solid phase to obtain a bimetallic catalyst.

[0031]Then the bimetallic catalyst obtained for 5 was used to catalyze the dehydrochlorination of 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tube reactor. The reaction tube of the tube reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up to 400°C for reaction. The reaction pressure is normal pressure. Before the reaction, pass N 2 (with an airspeed of 4000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200 °C at a rate of 5 °C / min and dried for 2 h. Then, the temperature was raised to 400°C at a rate of 5°C / min and the catalyst was treated for 2 hours, then the temperature was lowere...

Embodiment 7

[0036] The barium hydroxide was placed in a roasting furnace at 800°C for 4 hours to obtain a barium oxide catalyst. Barium oxide was treated with 20 mL / min of HCl gas for 5 h to obtain a barium chloride catalyst.

[0037] The obtained barium chloride catalyst is then used to catalyze the removal of HCl from 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tube reactor. The reaction tube of the tube reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up to 400°C for reaction. The reaction pressure is normal pressure. Before the reaction, pass N 2 (with an airspeed of 1000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200 °C at a rate of 5 °C / min and dried for 2 h. Then, the temperature was raised to 400°C at a rate of 5°C / min and the catalyst was treated for 2 hours, then the temperature was lowered to 200°C, and HCFC-14...

technical field

[0001] The invention belongs to the technical field of preparation of chlorofluoroolefins, and in particular relates to a preparation method of 1,1-difluoroethylene. The method prepares 1,1-difluoroethylene through catalytic dehydrochlorination. Background technique

[0002] 1,1-Difluoroethylene (vinylidene fluoride) is one of the important varieties of fluorine-containing olefins, mainly used in the production of poly-1,1-difluoroethylene resin, fluororubber and fluorine-containing copolymers such as 1,1-difluoroethylene Fluoroethylene-hexafluoropropylene, 1,1-difluoroethylene-1,1-difluoroethylene, 1,1-difluoroethylene-tetrafluoroethylene-hexafluoropropylene, etc. In addition, the fluorine rubber obtained by the copolymerization of 1,1-difluoroethylene, hexafluoropropylene and tetrafluoroethylene has become an indispensable product in modern industry, especially in high-tech fields, because of its excellent high temperature resistance, oil resistance, solven...

Examples

Embodiment 1

[0027] Barium hydroxide is placed in a roasting furnace at 800 ° C for 4 hours to obtain a barium oxide catalyst,

[0028] The obtained barium oxide catalyst is then used to catalyze the removal of HCl from 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tubular reactor. The reaction tube of the tubular reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up and the temperature is raised to 400°C for reaction. The reaction pressure At normal pressure, before the reaction, N 2 (with an airspeed of 1000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200°C at a rate of 5°C / min and dried for 2 h, then raised to 400°C at a rate of 5°C / min and then cooled to 200°C after catalyst treatment for 2 h. HCFC-142b continued to process for another 2 hours. After heating up to 400°C, pass HCFC-142b and N 2 The mixed gas undergoes a gas-...

Embodiment 2-6

[0030] Barium hydroxide is placed in a roasting furnace at 800 ° C for 4 h to obtain a barium oxide catalyst, and 5 wt % of CoF 3 、NiF 2 、CuF 2 、LaF 3 , CeF 3 Mix with barium oxide in solid phase to obtain a bimetallic catalyst.

[0031]Then the bimetallic catalyst obtained for 5 was used to catalyze the dehydrochlorination of 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tube reactor. The reaction tube of the tube reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up to 400°C for reaction. The reaction pressure is normal pressure. Before the reaction, pass N 2 (with an airspeed of 4000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200 °C at a rate of 5 °C / min and dried for 2 h. Then, the temperature was raised to 400°C at a rate of 5°C / min and the catalyst was treated for 2 hours, then the temperature was lowere...

Embodiment 7

[0036] The barium hydroxide was placed in a roasting furnace at 800°C for 4 hours to obtain a barium oxide catalyst. Barium oxide was treated with 20 mL / min of HCl gas for 5 h to obtain a barium chloride catalyst.

[0037] The obtained barium chloride catalyst is then used to catalyze the removal of HCl from 1,1-difluoro-1-chloroethane to prepare 1,1-difluoroethylene. The reaction is carried out in a plug-flow tube reactor. The reaction tube of the tube reactor is a Ni tube with an inner diameter of 20mm and a length of 800mm, and is placed in a heating furnace to heat up to 400°C for reaction. The reaction pressure is normal pressure. Before the reaction, pass N 2 (with an airspeed of 1000 h -1 ), the temperature of the catalyst bed was raised from room temperature to 200 °C at a rate of 5 °C / min and dried for 2 h. Then, the temperature was raised to 400°C at a rate of 5°C / min and the catalyst was treated for 2 hours, then the temperature was lowered to 200°C, and HCFC-14...