Non-thermal plasma polymerization of HFC-134a in argon bath gas has been studied in a dielectric barrier discharge reactor at atmospheric pressure and in the absence of oxygen and nitrogen. The reaction resulted in the formation of a polymeric solid fraction and the non-crosslinked properties of this material assisted in its characterization by solution state 13 C and 19 F NMR spectroscopy. Gel permeation chromatography (GPC) revealed that the polymers include low (number average molecular weight, M n values between 900 g mol -1 and 3000 g mol -1 ) and high (M n approximately 60 000 g mol -1 ) molecular weight fractions. A detailed polymerization mechanism is proposed, based on published literature and the findings of the current investigation.
This paper investigates the reaction of chloroform under non oxidative conditions in a quartz dielectric barrier discharge reactor. A non thermal plasma is generated in the dielectric barrier discharge reactor at atmospheric pressure where argon functions as a carrier gas and is mixed with chloroform and fed into the plasma zone. Parameters such as chloroform conversion, product distribution, reactor temperature and polymer characterisation are studied in this paper. A reaction mechanism outlining the reaction steps leading to the formation of major products is presented.
This paper describes an alternative process for chloroform decomposition via nonthermal plasma polymerization at atmospheric pressure and investigates the effect of methane and hydrogen addition on the process. The effect of both additives was assessed separately, where experiments were conducted in a double dielectric barrier discharge reactor under nonoxidative conditions. The most profound impact of the additives was a significant increase in the yield of non-cross-linked polymer produced compared to that in their absence. The addition of methane resulted in a 120% increase in polymer yield, while in hydrogen the increase was 31%. Critical parameters such as effect of the methane and hydrogen concentration on the conversion of chloroform at various applied voltages, the product distribution, mass balance, and polymer characterization are elucidated in this paper. Single pass conversions of 61% and 68% (with corresponding mass balances of 98% and 95%, respectively) were achieved for CHCl3 + CH4 and CHCl3 + H2 feed scenarios, respectively. Furthermore, a polymerization mechanism which explains the formation of major chain structures as well as structural defects in the polymer is expounded upon in the paper.
A dielectric barrier discharge (DBD) nonthermal plasma was used to convert a range of fluorocarbons into useful polymeric products. Reactions were conducted at atmospheric pressure, in an argon bath gas and where methane was added as reactant. The bulk gas temperature was less than 150 °C and yielded polymers from a number of methane/fluorocarbon mixtures, including fluorocarbons such as halons, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs). The results of gel permeation chromatography (GPC) reveal that a potentially valuable polymer is synthesized, with a number average molecular weight of between 60 000 and 130 000 g mol–1 and a polydispersity index (PDI) of between 1.2 and 2.9, depending on the fluorochemical converted.
In this study, the decomposition of methane in a nonequilibrium plasma, where nitrogen and oxygen were excluded from the feed mixture, was investigated. The major product species formed under conditions where the conversion level of methane was relatively high (up to 50 %) were determined. Hydrogen, acetylene, ethylene, ethane and propane were the primary gaseous species identified, and a liquid fraction was detected, which was characterised by 1 H NMR and gel permeation chromatography. The product spectrum formed in the nonequilibrium plasma is compared to the species profile predicted from methane pyrolysis, where the feed composition, residence time and methane conversion levels used in the high temperature pyrolysis simulation matched those in the nonequilibrium plasma experimental reactor.
Summary form only given. The reaction of CCl 3 F (CFC-11) with CH 4 in a non-equilibrium plasma has been examined. CFC-11 has the highest ozone depleting potential (ODP) among all refrigerants used commercially (ODP value of 1) and also has very high global warming potential (GWP) of 4680 and an atmospheric lifetime of 45 years. The manufacture of CFC-11 was banned by the Montreal Protocol in 1996 due to its deleterious effects on Earth's ozone layer. It is widely recognized that significant quantities of CFC-11 remain in polyurethane foams in discarded refrigerators or refrigerators awaiting disposal. While there are several methods developed to recover CFC-11 from polyurethane foams, a suitable process is required for its disposal. In this study, a dielectric barrier discharge reactor, employing alumina dielectrics (the detail description can be founds in 2 , 3 ), has been applied for the conversion of CFC-11 with the aim of synthesizing value-added materials. It has been found that polymers of non-crosslinked architecture can be synthesized from the reaction of CFC-11 and CH 4 . This work is focused on structural analyses of the polymers as well as discussions on conversion of CFC-11 under various conditions and characterization of the electrical discharge.
The reaction of CCl3F (CFC-11) with CH4 (in an argon bath gas) in a dielectric barrier discharge nonequilibrium plasma was examined. Oxygen and nitrogen were excluded from the feed stream and the reactions resulted in the production of fluorine-containing polymers, as well as a range of gaseous products including H2, HCl, HF, C2H3F, C2H3Cl, C2H2ClF, CHCl2F, CCl2F2, CH3Cl, CH2Cl2, CHCl3, and C2Cl4. The polymeric material synthesized during reaction is characterized as being non-cross-linked and random in nature, containing functional groups including CH3, CH2, CHCl, CHF, CF2, and CF3. The conversion level of CCl3F increased from 37% to 63% as the input energy density increased from 3 to 13 kJ L–1 (the applied voltage range was 14.1 to 15.2 kV, peak–peak). The electrical discharge was characterized and found to be a slight modification of filamentary discharge toward a diffuse discharge due to the presence of the relatively low concentration of CCl3F and CH4 (less than 2% each) in argon. A reaction mechanism is proposed describing the formation of gas phase, as well as polymeric products.
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