Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Han, Wenfeng; Kennedy, Eric M.; Mackie, John C.; Dlugogorski, Bogdan Z.

doi:10.1016/j.jhazmat.2010.04.011

Cited by 19 publications

(19 citation statements)

References 37 publications

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“…Following the decomposition of CHF 3 , various free radicals are produced, such as CF 2 , CHF 2 , CHF 2 CF 2 , F and H. Then, CH 4 is activated via a series of chain reactions facilitated by its reaction with these radicals (Reactions to ). This argument has been confirmed by conducting experiments with the addition of chain initiators such as CBrF 3 and CH 3 OH . In the absence of these initiators, chain reactions are initiated by CH 4 surface reaction only (reactor surface), such as Reaction .…”

Section: Resultsmentioning

confidence: 79%

“…Both CH 4 and CHF 3 are unreactive at low temperatures. Consequently, high reaction temperatures and additives such as CaBr 2 and CBrF 3 are suggested for the activation of CH 4 and CHF 3 . However, in the presence of HF (one of the major products) it poses a great challenge for the selection of a suitable reactor material.…”

Section: Resultsmentioning

confidence: 99%

“…Compared with CHF 3 , the conversion of CH 4 is usually even much lower when reaction is occurring under similar reaction conditions . 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 .…”

Section: Introductionmentioning

confidence: 94%

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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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Section: Resultsmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

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

et al. 2018

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“…Aiming at an environmentally more sustainable use of waste HFC-23 as a feedstock for the production of other valuable chemicals, we previously reported that CHF 3 can be converted to vinyl difluoride (VDF, CH 2 = CF 2 ), a highly valuable feedstock, via its reaction with CH 4 at temperatures between 973 and 1173 K [10]. With the introduction of various promoters, such as CaBr 2 [11], CBrF 3 [12] and CH 3 OH [13], both the conversions of reactants and yield of the target product, VDF can be improved significantly. In addition to VDF, CHF 3 also can be used as a feedstock, via reaction with I 2 , for the synthesis of another environmentally benign chemical, CF 3 I, which is a potential alternative as a fire-extinguishing agent, refrigerant, etching gas and CF 3 source for trifluoromethylation [14,15].…”

Section: Introductionmentioning

confidence: 99%

Pyrolysis of Trifluoromethane over Activated Carbon: Role of the Surface Oxygen Groups

Han

Jin

Chen

et al. 2014

Progress in Reaction Kinetics and Mechanism

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The pyrolysis of CHF 3 and CHClF 2 over activated carbons was investigated at 823 K, GHSV of 1820 h -1 and pressure of 1 bar. To elucidate the mechanism, activated carbons were treated in H 2 at 1123 K, HNO 3 solution at 363 K, N 2 at 873 K or supported with 4 wt% poly(acrylic acid sodium salt), respectively. The results confirm that following different treatments, the concentration of surface oxygen groups on activated carbons varies dramatically. These surface groups play important roles in the decomposition of CHF 3 and the product profiles. It is suggested that carboxylic groups are responsible for the formation of CF 3 and ultimately the product C 2 F 6 which results from the coupling of CF 3 , while the interaction between CHF 3 and hydroxyl or lactonic groups leads to the total destruction of CHF 3 and production of CO and CO 2 . Pyrolysis of CHClF 2 over activated carbon confirms that surface oxygen groups have no noticeable influence on the reactions of CF 2 . By contrast, a pure carbon surface is responsible for the disproportionation of CF 2 and formation of CF 3 .

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“…Recently, we reported that CBrClF 2 , CCl 2 F 2 and CHF 3 can be converted into vinylidene fluoride (CH 2 =CF 2 , VDF) via a reaction with CH 4 [8][9][10][11][12]. However, only single fluorochemical reactant was targeted during each of these studies.…”

Section: Introductionmentioning

confidence: 99%