CaBaFx composite as robust catalyst for the pyrolysis of 1-chloro-1,1-difluoroethane to vinylidene fluoride

Wang, Zhikun; Han, Wenfeng; Tang, Haodong; Liu, Huazhang

doi:10.1016/j.catcom.2018.11.011

Cited by 12 publications

(10 citation statements)

References 16 publications

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“…Due to the high reaction temperatures, coke formation and low selectivity are obtained . Recently, we have discovered that nitrogen-doped carbon and some of the metal fluorides are effective catalysts for the dehydrochlorination of HCFC-142b at a reaction temperature of only 350 °C. ,− In the presence of a proper catalyst, both high conversion of HCFC-142b and selectivity to VDF were achieved. However, the activity and stability vary with the kind of catalyst significantly.…”

Section: Introductionmentioning

confidence: 99%

Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

Han

Liu

Kang

et al. 2019

Ind. Eng. Chem. Res.

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Vinylidene fluoride (VDF) is one of the major fluorinated monomers. Currently, it is produced via the pyrolysis of 1-chloro-1,1-difluoroethane at above 650 °C without any catalyst. Herein, we propose that metal fluorides are promising catalysts that selectively promote the pyrolysis at 300–450 °C. With various metal fluorides as the catalysts, the conversion rate increases with the amount of acidic sites, which is also reinforced by the Bader charges q. The affinity to Cl of the metal fluorides is responsible for the selectivity. However, the high affinity to Cl also leads to the chlorination of metal fluorides forming metal chlorides followed by the deactivation of the catalyst. Different from other metal fluorides, F defects play a major role in the performance of AlF3. With an increase in F defects, the selectivity changes from vinylidene chlorofluoride (dehydrofluorination) to VDF (dehydrochlorination), which further confirms the role of affinity to Cl in the selectivity.

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Section: Introductionmentioning

confidence: 99%

Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

Han

Liu

Kang

et al. 2019

Ind. Eng. Chem. Res.

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“…Among various metal fluorides, SrF 2 has high activity for cleavage of HCFC-142b to VDF, but its selectivity is low [18,19]. In addition, BaF 2 also shows high activity in this reaction, and the selectivity to VDF is 95% [20]. However, during the dehydrochlorination reaction, BaF 2 tends to be chlorinated by F species to BaClF under the reaction conditions [21].…”

Section: Introductionmentioning

confidence: 99%

BaF(p-BDC)0.5 as the Catalyst Precursor for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

Wang

et al. 2021

Catalysts

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A BaF(p-BDC)0.5 catalyst was prepared by solid state reaction at room temperature with Ba(OH)2 as precursor, NH4F as F source, and H2(p-BDC) as organic ligand. The calcined samples were used as catalysts for dehydrochlorination of 1-chloro-1,1-difluoroethane to generate vinylidene fluoride (VDF) at 350 °C. Commercial production of VDF is carried out at 600–700 °C. Clearly, pyrolysis of the BaF(p-BDC)0.5 catalyst provided a promising way to prepare VDF at low temperatures. Prior to calcination, the activity of the BaF(p-BDC)0.5 catalyst was low. Following calcination at high temperatures, BaF(p-BDC)0.5 decomposed to BaF2 and BaCO3, and then the catalyst was chlorinated and fluorinated to BaClF, which showed high activity and stable VDF selectivity for dehydrochlorination of 1-Chloro-1,1-Difluoroethane to VDF.

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“…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].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the crystal growth, the presence of small amounts of Cl during catalyst preparation changed the chemical state of Ba, and therefore the adsorption and activation of the C-Cl bond for HCFC-142b were altered.Catalysts 2020, 10, 377 2 of 13 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.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.…”

mentioning

confidence: 99%

“…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.…”

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confidence: 99%

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Facile Preparation of BaClxFy for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

Han

Liu

et al. 2020

Catalysts

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BaClxFy as well as BaF2 and BaClF catalysts were prepared by solid-state reaction at room temperature with Ba(OH)2 as the precursor and NH4F/NH4Cl as the F and Cl sources. The catalysts were applied for the dehydrochlorination of 1-chloro-1,1-difluoroethane to vinylidene fluoride at 350 °C. The industrial manufacture of vinylidene fluoride (VDF) is carried out at 600–700 °C, whereas the BaClxFy catalysts provided a promising pathway to produce VDF at much lower temperatures. Unfortunately, the selectivity of VDF over BaF2 decreased from 94% to 84% along with the deactivation of the BaF2 catalyst monotonically. In the presence of small amounts of Cl in BaF2, stabilized selectivity was achieved. Over BaCl0.05F0.95, BaCl0.1F0.9 and BaCl0.25F0.75, no decrease in VDF selectivity was observed. Clearly, the presence of small amounts Cl during solid-state preparation inhibited the growth of BaF2 crystalline significantly. Far smaller particles were achieved. The particle size, or more precisely, the crystal size of the barium catalyst played a major role in the catalytic performance. In addition to the crystal growth, the presence of small amounts of Cl during catalyst preparation changed the chemical state of Ba, and therefore the adsorption and activation of the C–Cl bond for HCFC-142b were altered.

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CaBaFx composite as robust catalyst for the pyrolysis of 1-chloro-1,1-difluoroethane to vinylidene fluoride

Cited by 12 publications

References 16 publications

Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

BaF(p-BDC)0.5 as the Catalyst Precursor for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

Facile Preparation of BaClxFy for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

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