Decomposition Mechanism of Fluorinated Compounds in Water Plasmas Generated Under Atmospheric Pressure

Abstract

Decomposition mechanism of HFC-134a, and CF 4 in water plasmas at atmospheric pressure has been investigated. The decomposition efficiency of 99.9% can be obtained up to 3.17 mol kWh -1 of the ratio of hydrofluorocarbon (HFC) feed rate to the arc power and 1.89 mol kWh -1 of the ratio of perfluorocarbon (PFC) feed rate to the arc power. The species such as H 2 , CO, CO 2 , CH 4 , and CF 4 were detected from the effluent gas of both PFC and HFC decomposition. However, CH 2 F 2 and CHF 3 were observed only in the case of HFC decomposition. The HFC and PFC decomposition generate CH 2 F, CHF x (x:1-2) , and CF y (y:1-3) radicals, then those radicals were subsequently oxidized by oxygen, leading to CO and CO 2 generation in the excess oxygen condition. However, when there is insufficient oxygen available, those radicals were easily recombined with fluorine to form by-product such as CH 2 F 2 , CHF 3 , and CF 4 .

Thermal Plasma Decomposition of Fluorinated Greenhouse Gases

“…5 [29]. Large amounts of fluorinated byproducts such as CF4, CF3, CF2, CF, and F are generated by elevating the temperature without water as shown in Fig.…”

“…Instead of chemical catalyst, atmospheric pressure nonequilibrium plasma, and combustion methods, adoption of the thermal plasma method is gradually increasing to decompose fluorinated compounds in recent years [24][25][26][27][28][29][30][31][32][33]. Thermal plasma technology for waste treatment including destruction of fluorinated compounds has received a great deal of attention to meet the contemporary needs of solving problems with increasing environmental pollution and their restrictions to be followed [34][35][36][37][38][39].…”

Sustainable degradation of carbon tetrafluoride to non-corrosive useful products by incorporating reduced electron mediator within electro-scrubbing

“…The two primary existing technologies are combustion and plasma arc [3][4][5][6]. Whilst the plasma etching technique could potentially be used in the electronic manufacturing industries, plasma will not typically achieve complete perfluoro gas degradation which results in formation of byproducts, notably another greenhouse gas, CO2, and its derivatives (COF2, CO, H2O), with HF depending on the carrier gas [7][8][9][10]. Catalytic…”

Plasma jet characteristics in long DC arc with ring-shaped anode

“…The distinct advantages of thermal plasmas in the waste decomposition are high temperature and abundant radicals, which promote the decomposition and conversion of waste into environmentally benign materials in a compact system. Since the temperature of typical thermal plasma is over 10,000 K, thermal plasma can destroy any kind of non-degradable material preventing the generation of undesired chemical compounds such as furan, dioxin, sulfur oxides, nitrogen oxides in waste treatment processes (Heberlein and Murphy, 2008;Narengerile et al, 2010).…”