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1 ,1-difluoroethylene (VDF) is one of the major fluoromonomers which are the feedstock for the production of various resins, rubbers membrane and paints
Wenfeng Han
 + 1291 word(s) 1291 2020-05-26 07:40:28 |
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Yu, W.; Han, W.; Liu, Y.; Lu, J.; Yang, H.; Liu, B.; Tang, H.; Chen, A.; Li, Y. Vinylidene Fluoride. Encyclopedia. Available online: https://encyclopedia.pub/entry/920 (accessed on 19 April 2024).
Yu W, Han W, Liu Y, Lu J, Yang H, Liu B, et al. Vinylidene Fluoride. Encyclopedia. Available at: https://encyclopedia.pub/entry/920. Accessed April 19, 2024.
Yu, Wei, Wenfeng Han, Yongnan Liu, Jiaqin Lu, Hong Yang, Bing Liu, Haodong Tang, Aimin Chen, Ying Li. "Vinylidene Fluoride" Encyclopedia, https://encyclopedia.pub/entry/920 (accessed April 19, 2024).
Yu, W., Han, W., Liu, Y., Lu, J., Yang, H., Liu, B., Tang, H., Chen, A., & Li, Y. (2020, May 26). Vinylidene Fluoride. In Encyclopedia. https://encyclopedia.pub/entry/920
Yu, Wei, et al. "Vinylidene Fluoride." Encyclopedia. Web. 26 May, 2020.
Vinylidene Fluoride
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This entry is adapted from the peer-reviewed paper 10.3390/catal10040377

1,1-difluoroethylene (VDF) is one of the major fluoromonomers, which are the feedstock for the production of various resins, rubbers membrane and paints. The polymers derived from VDF (PVDF) or co-polymers with unique chemical resistance, stability at elevated temperatures, oxidation resistance, weatherability, piezoelectricity, dielectric and thermoelectricity, find wide applications in areas including petrochemical, electronic and electrical, and fluorocarbon coating. VDF is the second largest product among fluorocarbons with an annual production capacity of above 53,000 tons. The demand for VDF is increasing rapidly. At present, in industry, VDF is usually produced via the dehydrochlorination of 1,1-difluoro-1-chloroethane (HCFC-142b) at reaction temperatures above 650 °C

barium chlorofluoride catalytic pyrolysis barium fluoride dehydrochlorination 1-chloro-1,1-difluoroethane vinylidene fluoride

1. Introduction

1,1-difluoroethylene (VDF) is one of the major fluoromonomers, which are the feedstock for the production of various resins, rubbers membrane and paints [1]. The polymers derived from VDF (PVDF) or co-polymers with unique chemical resistance, stability at elevated temperatures, oxidation resistance, weatherability, piezoelectricity, dielectric and thermoelectricity, find wide applications in areas including petrochemical, electronic and electrical, and fluorocarbon coating [2]. VDF is the second largest product among fluorocarbons with an annual production capacity of above 53,000 tons. The demand for VDF is increasing rapidly. At present, in industry, VDF is usually produced via the dehydrochlorination of 1,1-difluoro-1-chloroethane (HCFC-142b) at reaction temperatures above 650 °C [3][4]. Dehydrochlorination is an efficient route for the preparation of 1, 1-dichloroethylene (VDC), vinyl chloride monomer (VCM), 2,3,3,3-tetrafluoropropene (HFO-1234yf), and ethylene oxychlorination [5][6][7][8]. As the dehydrochlorination of HCFC-142b is a highly endothermic reaction, very long reaction tubes are adopted to supply the reaction heat. Unfortunately, this also leads to the generation of carbon deposition during the reaction process at elevated temperatures. Consequently, the reactor needs to be cut off to remove the coke after a period of reaction, which significantly reduces the efficiency of continuous production.[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]

2. Specifics

We have reported that the dehydrochlorination of HCFC-142b is promoted by catalysts such as N-doped activated carbon [9], N-containing mesoporous carbon [10], and metal fluorides [3][4]. The presence of catalysts reduces the reaction temperature from 650 °C to lower than 350 °C, facilitating saving energy consumption and avoiding the formation of coke during reaction. Although N-doped activated carbon and mesoporous carbon materials exhibit a moderate conversion of HCFC-142b and high selectivity to VDF, they are difficult to recover following deactivation by coking. SrF2 shows a high activity for the pyrolysis of HCFC-142b to VDF under moderate conditions. However, its selectivity and stability are rather low [4]. Although the preparation of SrF2 microparticles with cubic structures improves the performance, the procedure is complicated and it is difficult to scale-up.

Due to the formation of highly corrosive byproducts, HCl and HF, during pyrolysis of HCFC-142b, there are very rare choices for the exploration of proper materials as the catalysts. Therefore, carbon materials and metal fluorides which are HF-corrosion-resistant are the potential catalysts. In addition to carbon materials, metal fluorides were also systematically investigated for the catalytic pyrolysis of HCFC-142b [11]. Among the various metal fluorides, barium fluoride shows relatively high activity in this reaction, with selectivity to VDF of 95% [11]. Other metal fluorides, such as MgF2, AlF3 and fluorinated Cr2O3 were found to be catalysts for dehydrofluorination reactions [12][13][14]. Similar to the chlorination of AlF3 to aluminum chlorofluoride (ACF), BaF2 also tends to be chlorinated to BaClF by Cl species under reaction conditions [15]. Consequently, a rapid decrease in the conversion of HCFC-142b and selectivity to VDF was observed. In a similar reaction system for dehydrofluorination, which was catalyzed by AlF3, strong Lewis acid promoted both dehydrofluorination and coke deposition. As a result, a fast deactivation was seen. It was reported that the pre-deposition of carbon prior to reaction leads to the partial coverage of strong Lewis acid sites and improves the stability of catalysts [16]. As reported previously, BaF2 converts to BaClF via reaction with HCl at reaction temperatures, resulting in the deactivation of the catalyst [11][17]. Clearly, the inhibition of chlorination of the BaF2 catalyst by Cl species is one of the key challenges for the catalytic pyrolysis of HCFC-142b.

References

  1. Ameduri, B. From Vinylidene Fluoride (VDF) to the Applications of VDF-Containing Polymers and Copolymers: Recent Developments and Future Trends. Chemical Reviews 2009, 109, 6632-6686, doi:10.1021/cr800187m.
  2. Améduri, B.; Boutevin, B.; Kostov, G. Fluoroelastomers: synthesis, properties and applications. Progress in Polymer Science 2001, 26, 105-187, doi:https://doi.org/10.1016/S0079-6700(00)00044-7.
  3. Wang, Z.; Han, W.; Tang, H.; Liu, H. CaBaFx composite as robust catalyst for the pyrolysis of 1-chloro-1,1-difluoroethane to vinylidene fluoride. Catalysis Communications 2019, 120, 42-45, doi:10.1016/j.catcom.2018.11.011.
  4. Wang, Z.; Han, W.; Liu, H. EDTA-assisted hydrothermal synthesis of cubic SrF2 particles and their catalytic performance for the pyrolysis of 1-chloro-1,1-difluoroethane to vinylidene fluoride. Crystengcomm 2019, 21, 1691-1700, doi:10.1039/c8ce01546e.
  5. Zhang, P.Z.; Jiang, Z.B.; Cui, Y.H.; Xie, G.Q.; Jin, Y.Z.; Guo, L.L.; Xu, Y.Q.; Zhang, Q.F.; Li, X.N. Catalytic performance of ionic liquid for dehydrochlorination reaction: Excellent activity and unparalled stability. Applied Catalysis B-Environmental 2019, 255, 10, doi:10.1016/j.apcatb.2019.117757.
  6. Sun, X.; Liu, X.; Qin, Y.C.; Qiang, L.; He, Y.P.; Su, D.S.; Song, L.J.; Sun, Z.L. Direct Conversion of Acetylene and 1,2-Dichloroethane to Vinyl Chloride Monomer over a Supported Carbon Nitride Catalyst: Tunable Activity Controlled by the Synthesis Temperature. Industrial & Engineering Chemistry Research 2019, 58, 5404-5413, doi:10.1021/acs.iecr.8b05942.
  7. Mao, W.; Bai, Y.; Wang, W.; Wang, B.; Xu, Q.; Shi, L.; Li, C.; Lu, J. Highly Selective Dehydrochlorination of 1,1,1,2-Tetrafluoro-2-chloropropane to 2,3,3,3-Tetrafluoropropene over Alkali Metal Fluoride Modified MgO Catalysts. ChemCatChem 2017, 9, 824-832, doi:10.1002/cctc.201601259.
  8. Scharfe, M.; Zichittella, G.; Kondratenko, V.A.; Kondratenko, E.V.; Lopez, N.; Perez-Ramirez, J. Mechanistic origin of the diverging selectivity patterns in catalyzed ethane and ethene oxychlorination. Journal of Catalysis 2019, 377, 233-244, doi:10.1016/j.jcat.2019.07.021.
  9. Wang, Z.; Han, W.; Zhang, C.; Zhou, S.; Wang, H.; Tang, H.; Liu, H. Preparation of N-Doped Activated Carbon for Catalytic Pyrolysis of 1-Chloro-1,1-difluoroethane to Vinylidene Fluoride. Chemistryselect 2018, 3, 1015-1018, doi:10.1002/slct.201701931.
  10. Wang, Z.; Han, W.; Tang, H.; Li, Y.; Liu, H. Preparation of N-doped ordered mesoporous carbon and catalytic performance for the pyrolysis of 1-chloro-1,1-difluoroethane to vinylidene fluoride. Microporous and Mesoporous Materials 2019, 275, 200-206, doi:10.1016/j.micromeso.2018.08.020.
  11. Han, W.; Liu, B.; Kang, Y.; Wang, Z.; Yu, W.; Yang, H.; Liu, Y.; Lu, J.; Tang, H.; Li, Y., et al. Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides. Industrial & Engineering Chemistry Research 2019, 58, 18149-18159, doi:10.1021/acs.iecr.9b03976.
  12. Han, W.; Zhang, C.; Wang, H.; Zhou, S.; Tang, H.; Yang, L.; Wang, Z. Sub-nano MgF2 embedded in carbon nanofibers and electrospun MgF2 nanofibers by one-step electrospinning as highly efficient catalysts for 1,1,1-trifluoroethane dehydrofluorination. Catalysis Science & Technology 2017, 7, 6000-6012, doi:10.1039/c7cy02056b.
  13. Han, W.; Wang, H.; Liu, B.; Li, X.; Tang, H.; Li, Y.; Liu, H. PVDF mediated fabrication of freestanding AlF3 sub-microspheres: Facile and controllable synthesis of alpha, beta and theta-AlF3. Materials Chemistry and Physics 2020, 240, doi:10.1016/j.matchemphys.2019.122287.
  14. Liu, B.; Han, W.; Li, X.; Li, L.; Tang, H.; Lu, C.; Li, Y.; Li, X. Quasi metal organic framework with highly concentrated Cr2O3 molecular clusters as the efficient catalyst for dehydrofluorination of 1,1,1,3,3-pentafluoropropane. Applied Catalysis B-Environmental 2019, 257, doi:10.1016/j.apcatb.2019.117939.
  15. Calvo, B.; Marshall, C.P.; Krahl, T.; Krohnert, J.; Trunschke, A.; Scholz, G.; Braun, T.; Kemnitz, E. Comparative study of the strongest solid Lewis acids known: ACF and HS-AlF3. Dalton Trans. 2018, 47, 16461-16473, doi:10.1039/c8dt03279c.
  16. Fang, X.-X.; Wang, Y.; Jia, W.-Z.; Song, J.-D.; Wang, Y.-J.; Luo, M.-F.; Lu, J.-Q. Dehydrofluorination of 1, 1, 1, 3, 3-pentafluoropropane over C-AlF3 composite catalysts: Improved catalyst stability by the presence of pre-deposited carbon. Applied Catalysis a-General 2019, 576, 39-46, doi:10.1016/j.apcata.2019.02.035.
  17. Teinz, K.; Wuttke, S.; Boerno, F.; Eicher, J.; Kemnitz, E. Highly selective metal fluoride catalysts for the dehydrohalogenation of 3-chloro-1,1,1,3-tetrafluorobutane. Journal of Catalysis 2011, 282, 175-182, doi:10.1016/j.jcat.2011.06.013.
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Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register :
Wei Yu
,
Wenfeng Han
,
Yongnan Liu
,
Jiaqin Lu
,
Hong Yang
,
Bing Liu
,
Haodong Tang
,
Aimin Chen
,
Ying Li
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Update Date: 30 Oct 2020
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