2837-89-0Relevant academic research and scientific papers
HYDROGENOLYSIS OF DICHLOROTETRAFLUOROETHANE ISOMERIC MIXTURES FOR THE FORMATION OF 1,1,1,2-TETRAFLUOROETHANE
Gervasutti, C.,Marangoni, L.,Marra, W.
, p. 1 - 20 (1982)
1,1,1,2-tetrafluoroethane was prepared from isomeric mixtures of dichlorotetrafluoroethanes through selective hydrogenolysis of CF3-CCl2F catalyzed by Pd/C.The other isomer CClF2-CClF2 appeared more stable to hydrogenolysis and was only converted partially to the monohydrogenated derivative CHF2-CClF2.The influences of the three most important operating parameters were defined on the basis of a statistical testing program.The mathematical elaboration of the experimental data allowed definition of the relationships by which it is possible to foresee conversion of CF3-CCl2F, yield of CF3-CH2F and concentration of reaction products, such as CF3-CH3, CF3-CH2F, CF3-CHClF and CClF2-CHF2 in terms of the above parameters.
Turnover Rate, Reaction Order, and Elementary Steps for the Hydrodechlorination of Chlorofluorocarbon Compounds on Palladium Catalysts
Thompson,Rioux,Chen,Ribeiro
, p. 3067 - 3077 (2000)
The rates of hydrodechlorination catalyzed by Pd supported on carbon for four chlorofluorocarbons spanned a range of 7 orders of magnitude. The rates scaled up to the bond strength of the carbon-chlorine bond for the gas-phase reactant. This finding demonstrates that the rate-determining step involves the scission of the C-Cl bond and suggests, through Polanyi and linear free-energy relationships, that rates for other compounds can be estimated if the C-Cl bond strength is known. The reaction orders for the most abundant products are approximately first-order for the chlorine-containing compound, half-order in H2, and inverse first-order in HCl. The reaction steps consistent with these orders include a rate-determining step involving the adsorption of the chlorofluorocarbon to a single site (which could be a single surface palladium atom) and equilibrated steps between gas-phase H2, gas-phase HCl, and adsorbed hydrogen and chlorine atoms. The rates on the supported catalysts are comparable to the ones reported before on a Pd foil, indicating that the support does not play a role in the reaction. The product distribution is independent of conversion, implying that the various products are formed from a single visit of the reactant on the surface and not from readsorption of gas-phase products. The four compounds studied were chloropentafluoroethane (CF3-CF2Cl), 2-chloro-1,1,1,2-tetrafluoroethane (CF3-CFClH), 1,1-dichlorotetrafluoroethane (CF3-CFCl2), and 1,1,1-trichloro-2,2,2-trifluoroethane (CF3-CCl3).
Hydrodechlorination of 1,1-dichlorotetrafluoroethane and dichlorodifluoromethane catalyzed by Pd on fluorinated aluminas: The role of support material
Early, Kintu,Kovalchuk, Vladimir I.,Lonyi, Ferenc,Deshmukh, Subodh,D'Itri, Julie L.
, p. 219 - 227 (1999)
The gas phase hydrodechlorination of CF3CFCl2 to CF3CFH2 and CF2Cl2 to CF2H2 catalyzed by Pd supported on Al2O3, a series of fluorinated Al2O3, and AlF3 was investigated. A combination of reaction kinetics investigations and characterization by in situ FTIR spectroscopy has been performed. It has been found that for reactions involving CF3CFCl2, all catalysts exhibit a rapid and significant decrease in activity; however, little change in activity with time on stream occurs with CF2Cl2. FTIR investigations suggest the occurrence of direct reaction between the CFC and the support material, which results in the consumption of hydroxyl groups during the early stages of reaction. The effect of fluorination of support on catalytic behavior of Pd is discussed.
Structure Insensitivity and Effect of Sulfur in the Reaction of Hydrodechlorination of 1,1-Dichlorotetrafluoroethane (CF3-CFCl2 ) over Pd Catalysts
Ribeiro,Gerken,Rupprechter,Somorjai,Kellner,Coulston,Manzer,Abrams
, p. 352 - 357 (1998)
The kinetics of the hydrodechlorination of 1,1-dichlorotetrafluoroethane (CFC 114a) was studied on Pd(111), Pd(100), and a Pd foil at atmospheric pressure. The three products formed were CF3-CFH2 (HFC 134a), CF3-CFClH (HCFC 124), and CF3-CH3 (HFC 143a) with selectivities independent of conversion. The single crystals and foil (model catalysts) were studied in an apparatus that permitted the direct transfer of samples between a high pressure cell (1 atm) and an ultrahigh vacuum chamber. The reaction rates were measured in the temperature range of 350 to 470 K. The reaction is not sensitive to the structure of the catalyst, as indicated by the similar turnover rates for all catalysts tested. The reaction is inverse first order in the reaction product HCl on all samples. Sulfur adsorbed on the Pd surface depressed the rates of formation of 134a more strongly than the rates of 124 and 143a.
Effects of M-promoter (M = Y, Co, La, Zn) on Cr2O3 catalysts for fluorination of perchloroethylene
Cheng, Yong-Xiang,Fan, Jing-Lian,Xie, Zun-Yun,Lu, Ji-Qing,Luo, Meng-Fei
, p. 66 - 72 (2013)
The vapor phase fluorination of perchloroethylene (PCE) to synthesize 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 1-chloro-1,2,2,2- tetrafluoroethane (HCFC-124) and pentafluoroethane (HFC-125) was carried out on M-Cr2O3 catalysts with different promoters (M = Y, Co, La, Zn). The catalysts were characterized by X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), Raman spectrum, Ammonia temperature-programmed desorption (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) techniques. It was found that in the pre-fluorination process CrOx (x ≥ 1.5) in M-Cr2O3 catalysts could be transformed into CrOxFy species. The highest activity was obtained on La-Cr2O3(F) catalyst with 90.6% of PCE conversion and 93.7% to total selectivity (HCFC-123 + HCFC-124 + HFC-125) at 300 C. The decline in surface acid sites density of the catalyst could improve the specific reaction rate, and the formation of surface CrOxF y species could enhance the selectivities to HCFC-123, HCFC-124 and HFC-125 for gas phase fluorination of PCE. Copyright - 2013 Published by Elsevier B.V. All rights reserved.
Catalytic hydrodechlorination of 1,1-dichlorotetrafluoroethane by Pd/Al2O3
Karpinski, Zbigniew,Early, Kintu,D'Itri, Julie L.
, p. 378 - 386 (1996)
Palladium supported on γ-alumina displays high activity for the hydrodechlorination of 1,1-dichlorotetrafluoroethane. High H2 partial pressures are needed to avoid deactivation, and steady state is obtained after ～5 h time on stream. Under these conditions (H2/CFC feed ratio = 20) the reaction is zero order in H2 partial pressure and positive (0.65) order in 1,1-dichlorotetrafluoroethane partial pressure. Three main products are formed: 1,1,1,2-tetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, and 1,1,1-trifluoroethane, with approximately 85% selectivity toward the desired CF3CFH2. The apparent activation energies associated with the formation of each product range from 52 to 68 kJ/mol. All three major products have a nonzero rate of formation in the limit of zero conversion, the implication of which is that all are primary products. The kinetics results are consistent with a reaction mechanism involving a carbene intermediate. Variation of the temperature at which the catalyst is prereduced from 300 to 600°C results in an increase in particle size from 11-53 nm and in an increase in the hydrodechlorination TOF from 2.3 to 5.0 s-1.
Deuterium isotope studies of the hydrofluorination of chloroethenes over chromia catalysts
Kavanagh, David M. C.,Ryan, T. Anthony,Mile, Brynmor
, p. 167 - 176 (1993)
The mechanism of the catalytic fluorination of chloroalkenes over a chromia catalyst has been investigated by examining the effects of substituting DF for HF as the fluorine source for reaction with tetrachloroethene and trichloroethene.At a temperature of 250 degC and a HF (DF)/alkene molar ratio of 4.2:1, the rate of conversion of tetrachloroethene is increased by using DF and there is a concomitant increase in the selectivity to some chlorofluoroalkanes and a decrease in the selectivity to chlorofluoroalkenes.The opposite behaviour observed for the halogenated alkenes and alkanes indicates that the alkenes are not important intermediates in the production of the alkanes by a series of hydrofluorination and dehydrochlorination reactions.For tetrachloroethene, the main reaction pathway to the alkanes is a direct chlorine/fluorine exchange over a heavily fluorinated chromia surface with minimal C-H/C-D cleavage of intermediates.Substitution of DF for HF causes no change in the product selectivities from reaction with trichloroethene over chromia catalysts.However, the presence of dideutero - and monodeutero - products shows that both chlorine/fluorine exchange and HF addition / HCl elimination pathways are occurring for the less-substituted alkene.
Production Method for 1,2,2,2-Tetrafluoroethyl Difluoromethyl Ether (Desflurane)
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Paragraph 0180-0183, (2019/11/22)
Fluoral is obtained by gas-phase fluorination of chloral in the presence of a catalyst and then reacted with trimethyl orthoformate, thereby readily forming 1,2,2,2-tetrafluoroethyl methyl ether as an intermediate for production of desflurane. 1,2,2,2-Tetrafluoroethyl difluoromethyl ether (desflurane) is produced with high yield from the thus-formed 1,2,2,2-tetrafluoroethyl methyl ether by chlorination and fluorination. This method enables efficient industrial-scale production of desflurane useful as an inhalation anesthetic
PROCESS FOR PRODUCING FLUOROETHANE
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Paragraph 0048, (2015/12/04)
Fluorochromium oxide having a fluorine content of not less than 30 wt.% is used for the fluorination reaction. To provide a manufacturing method for fluorine-containing ethane which contains 1, 1, 1, 2, 2-pentafluoroethane as the main component in which the reaction can be performed while controlling the generation of CFCs to the greatest possible extent by fluorinating at least one selected from the group composed of tetrachloroethylene, 2, 2-dichloro-1, 1, 1-trifluoroethane and 2-chloro-1, 1, 1, 2-tetrafluoroethane with hydrogen fluoride.
Catalytic fluorination of 1,1,1-trifluoro-2-chloro-ethane in the presence of oxygen over chromium based catalyst doped or not by zinc supported over partially fluorinated alumina
Loustaunau,Fayolle-Romelaer,Celerier,Brunet
experimental part, p. 1262 - 1265 (2011/12/21)
The addition of zinc in low amount to chromium based catalyst supported over partially fluorinated alumina has a positive effect for the fluorination reaction of CF3CH2Cl in the presence of dioxygen in order to prevent the catalyst deactivation. However, under these operating conditions, the Deacon reaction by reaction with HCl produced by Cl/F exchanges could be involved. The formation of various by-products was observed corresponding to the addition of HCl or Cl2 into halogenated double bonds.
