Catalytic pyrolysis of CHF3 over activated carbon and activated carbon supported potassium catalyst

Han, Wenfeng; Kennedy, Eric M.; Liu, Huazhang; Li, Ying; Adesina, Adesoji A.; Mackie, John C.; Dlugogorski, Bogdan Z.

doi:10.1016/j.jfluchem.2010.03.002

Cited by 17 publications

(21 citation statements)

References 26 publications

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“…However, by comparing the pyrolysis of CHF 3 over AC treated in HNO 3 with that over AC treated in H 2 , Wenfeng Han et al suggested that the oxygen groups on surface of carbon may play a major role for the decomposition of CHF 3 . 1 However, CF 2 carbene, the most important intermediate for CF 3 I synthesis, has not been observed directly in the above experiments. The CF 2 disproportionation mechanism is still controversial.…”

Section: Introductionmentioning

confidence: 83%

CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

TaiPing²,

Liu

et al. 2014

J. Phys. Chem. A

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A revised reaction mechanism of CF3I synthesis catalyzed by activated carbon is investigated with quantum chemistry methods using density functional theory (DFT). The adsorption configurations of possible intermediates are carefully examined. The reaction pathway and related transition states are also analyzed. According to our calculations, first, the dehydrofluorination of CHF3 is catalyzed by -COOH groups, which possesses the highest barrier and is accordingly identified as the rate-determining step. Second, the difluorocarbene disproportionation over graphite (001) surface proceeds instead of dimerization. The next reaction steps involving the association of fluoromethine and trifluoromethyl, the fluorine abstractions between intermediates and the iodine abstractions by the desorbed CF3 and CF2CF3 from molecular iodine are also feasible over graphite (001) surfaces. It is also found that the coke deposition in experiments is due to the fluorine abstraction from fluoromethine. This revised mechanism is in agreement with available experimental data and our theoretical computations.

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Section: Introductionmentioning

confidence: 83%

CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

TaiPing²,

Liu

et al. 2014

J. Phys. Chem. A

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“…On the other side, CHF 3 activation mechanisms in heterogeneous reactions at temperatures below 973 K are much less clear and interpreted in a controversial manner. Some authors suggested that decomposition of CHF 3 on solid surfaces occurs by C-F bond activation through a C-FÁ Á ÁM + type of interactions [6,14,16]. Conversely, activity of CHF 3 in fluorination of g-Al 2 O 3 was interpreted by the initial rupture of the relatively weak C-H bond that leads to the formation of active fluorinating species [17].…”

Section: Activation Of Chf 3 By Hydroxides or Carbonates Through Acidmentioning

confidence: 99%

“…CHF 3 is characterised by a remarkable thermal stability. Under homogeneous gas phase conditions, discernible thermal decomposition (pyrolysis) of CHF 3 to hydrogen fluoride, HF, and difluorocarbene, CF 2 , starts above 973 K [5][6][7]. Majority of CHF 3 conversion processes was therefore studied at high temperatures, usually within the temperature range of 773-1273 K. Related homogeneous reactions of CHF 3 were, as a rule, rationalised on the basis of the initial thermally activated decomposition to CF 2 and HF [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…On the other side, investigations of diverse heterogeneous reactions, either catalytic [10,12,13] or non-catalytic [11,14], demonstrated a strong influence of surface processes on initial CHF 3 decomposition and subsequent reactions. In the presence of sufficiently stable solid catalysts, some reactions with CHF 3 could be performed at temperatures that were noticeably lower than those required by the non-catalysed reactions [6,12].…”

Section: Introductionmentioning

confidence: 99%

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Interaction of trifluoromethane (CHF3) with alkali hydroxides and carbonates

Vakulka

Tavčar

Škapin

2012

Journal of Fluorine Chemistry

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“…Although promoters such as CaBr 2 , CBrF 3 and CH 3 OH can effectively enhance the conversion of CH 4 , high temperatures are still required to achieve non‐negligible levels of CH 4 activation . In the reaction system under consideration in the current study, one of the key initial steps in the mechanism is suggested to be the decomposition of CHF 3 , forming CF 2 and HF . These species pose severe challenges in terms of the selection of reactor materials that can be operated in the highly corrosive HF atmosphere and at such high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

et al. 2018

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The oxidative coupling of methane (OCM) with CHF3 facilitates the synthesis of vinylidene fluoride (VDF). The aim is to utilize CHF3, which is otherwise considered a waste with a very high global warming potential. This study focuses on the effect of a LaOF catalyst on OCM occurring in the presence of CHF3, which engenders a promoting effect of O2 on CH4 activation. It examines the structural and phase changes of the lanthanum catalyst during the reaction and then speculates on the reaction mechanism. In combining OCM with CHF3, both the conversion of CH4 and the formation rate of VDF are almost tripled at 700°C. However, at higher temperatures, gas‐phase reactions play a dominating role in the conversion of CH4 and LaOF catalyst plays a very minor role in the reaction system at elevated temperatures. Irrespective of the reaction temperature, VDF is produced via the gas‐phase coupling of CH3 radicals with CF2. During pretreatment or during the reaction itself, La2O3 is fluorinated by CHF3 and HF, yielding the formation of surface LaOF and LaF3 species. LaF3 is a relatively inactive catalyst for CH4 conversion, whereas, in comparison LaOF appears to play a very important role in the activation of CH4 at low temperatures. The activation mechanism of CH4 at relatively low temperatures is similar with that postulated to occur during the OCM. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Catalytic pyrolysis of CHF3 over activated carbon and activated carbon supported potassium catalyst

Cited by 17 publications

References 26 publications

CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

Interaction of trifluoromethane (CHF3) with alkali hydroxides and carbonates

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

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Catalytic pyrolysis of CHF3 over activated carbon and activated carbon supported potassium catalyst

Cited by 17 publications

References 26 publications

CF3I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

CF3I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

Interaction of trifluoromethane (CHF3) with alkali hydroxides and carbonates

Catalytic coupling of CH4 with CHF3 for the synthesis of VDF over LaOF catalyst

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Product

Resources

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CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

CF₃I Synthesis Catalyzed by Activated Carbon: A Density Functional Theory Study

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst