A review of CFC and halon treatment technologies – The nature and role of catalysts

Abstract

The purpose of this review article is to provide readers with an account of CFC and halon treatment technologies as depicted in the patent and open literature. Destruction technologies, in which halons and CFCs are converted into species such as CO 2 , HX or X 2 (X = Br, Cl, F), are treated less extensively. Emphasis has been placed on conversion processes, which aim at transforming (rather than destroying) CFC or halon into environmentally benign and useful products. It has been found that catalytic hydrodehalogenation over transition metal based catalysts, Pd in particular, has great potential for conversion of CFCs and halons to hydrofluorocarbons. In this regard, the focus of this review is on catalytic hydrodehalogenation, including an assessment of reaction mechanisms, catalytic activity, selectivity and durability.

Influence of ZrO2 properties on catalytic hydrodechlorination of chlorobenzene over Pd/ZrO2 catalysts

“…This is also supported by XPS analysis of Pd species in used Pd/ZrO 2 catalysts. The contents of Pd 2+ in the used catalysts were found to be 18.0%, 12.5% and 16.0% for Pd/ZrO 2 -300, Pd/ZrO 2 -500 and Pd/ZrO 2 -600 respectively (see Table 2), reflecting the increased Pd 2+ contents in the used catalysts as compared with the fresh catalysts due to the strong binding of chlorine with Pd or the generation of palladium chloride in the catalytic HDC process [41]. Moreover, catalytic HDC led to a more prominent increase of Pd 2+ content in Pd/ZrO 2 -300, suggesting that Pd sites in Pd/ZrO 2 -300 are more susceptible to deactivation during HDC process probably due to its low content of Pd with strong metal-support interaction as compared with Pd/ZrO 2 -500 and Pd/ZrO 2 -600.…”

Effect of methane on the conversion of HFC-134a in a dielectric barrier discharge non-equilibrium plasma reactor

“…This is because the conversion of HFC-134a with methane forms hydrofluoric acid (HF) gas, which reacts aggressively and destructively with quartz or pyrex. Alumina is an HFresistant material that has been widely used in thermal reactors for the study of the thermal decomposition and reaction of CFCs and halons [21][22][23] and is also a suitable dielectric for construction of a DBD reactor. The DBD reactor can be of various geometries, including planar or cylindrical; in the present study a cylindrical configuration was chosen for construction of the reactor.…”

Destruction of Freon HFC-134a Using a Nozzleless Microwave Plasma Source

“…Conventional methods, e.g. adsorption, absorption and catalytic combustion, proved not to be efficient enough [1][2][3]. To deal with the problem, thermal plasma processing [1][2][3][4][5][6][7][8][9] has been commercialized as a method for the destruction of Freon-type refrigerants.…”

“…adsorption, absorption and catalytic combustion, proved not to be efficient enough [1][2][3]. To deal with the problem, thermal plasma processing [1][2][3][4][5][6][7][8][9] has been commercialized as a method for the destruction of Freon-type refrigerants. However, the thermal plasma techniques exhibit some drawbacks, which are high input power (from several kW up to hundreds kW), low energy efficiency and generation of harmful or even toxic oxygen compounds if applied under air environment.…”