Catalytic Wet Air Oxidation CWAO

Heterogeneous Catalysis Principles and Applications, 2nd edn., Oxford University Press, Oxford, 1987, p. 160. 

Thomas and W.J. Thomas, Principles and Practice of Heterogeneous Catalysis, VCH, Weinheim, 1997, p. 577. 

Bowker and R.W. Joyner, in Insights into Speciality Inorganic Chemicals D.T. Thompson, (ed.), Royal Society of Chemistry, Cambridge, UK, 1995. 

Gulari, R.H. Hammerle, C. Lambert, J. Leerat and S. Osuwan, Appl. Catal. A Chem. 226 (2002) 183. 

Pattrick, E. van der Lingen, C.W. Corti, R.J. Holliday and D.T. Thompson, Proc. CAPoC-6 Conference, Brussels, Belgium, 2003. 

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The Catalytic Wet Air Oxidation (CWAO) process is capable of converting all organic contaminants ultimately to carbon dioxide and water, and can also remove oxidizable inorganic components such as cyanides and ammonia. The process uses air as the oxidant, which is mixed with the effluent and passed over a catalyst at elevated temperatures and pressures. If complete COD removal is not required, the air rate, temperature and pressure can be reduced, therefore reducing the operating cost. CWAO is particularly cost-effective for effluents that are highly concentrated... 

Precious metals (Pt, Pd, Ru) deposited on supports have been reported to be active for catalytic wet air oxidation (CWAO). Gallezot et al [9] have shown that platinum catalysts supported on carbon could decompose formic, oxalic and maleic acids very easily, at... 

Heterogeneous catalysts systems are known to be promising for wastewaters treatments. The development of active and stable heterogeneous catalysts has received thus a great attention. In this light, the efficiency of several noble metals including (Pt, Pd, Ru, Rh..) for the catalytic wet air oxidation (CWAO) of various organics pollutants has been demonstrated [1]. For oxidation of acetic acid, ruthenium was one of the most active metals as underlined by... 

Environmental applications of metal-doped carbon gels can be divided between reactions carried out in the gas and aqueous phases. The former group includes volatile organic compound (VOC) oxidation (e.g., toluene and xylene oxidation) and NO reduction. The latter group includes the catalytic wet air oxidation (CWAO) of aniline solutions and advanced oxidation processes (AOPs) (e.g., catalytic ozonation and photooxidation of pollutants). 

In this case study, treatment was of typical high strength DWW by catalytic wet-air oxidation (CWAO) at atmospheric pressure and 343-373 K. Experiments were conducted to investigate the effects of temperature (T) and catalyst dosage (m) on the COD and colour removal. In this study, five catalysts were used, namely, CUSO4, ZnCl2, FeCls, Al(OH)3 and Cu (Il)-exchanged... 

Catalytic ozonation Photocatalytic ozonation Catalytic wet air oxidation (CWAO)... 

Different methods for the preparation of gold catalysts (mono and bimetallic) were used - the modified deposition-precipitation (MDP), the deposition-precipitation by ammonia (DPA) and the colloidal method (CM). The catalytic performances of all samples were evaluated in the catalytic wet air oxidation (CWAO) of succinic acid under mild conditions (190°C, 50 bar total pressure). The results showed that the preparation procedure and the addition of a second metal (Pt or Ru) clearly influence the catdytic activity and selectivity, depending on the size of the gold particles and the nature of the second metal. 

Concerning depollution strategies, the invesdgadon of Pd-only TWCs is possibly one of the hot topics in the most recent literature, " together with the study of total oxidadon processes hydrocarbon combustion, " selective soot particulate removal, " volatile organic compound (VOC) elimination and catalytic wet-air oxidation of organics (CWAO) " " and NO abatement. " ... 

Wet air oxidation in the presence of carbon-supported ruthenium provides an efficient method for total destruction by air of organic acid pollutants in aqueous solutions. In the presence of high concentrations of NaCl salts or of mineral acids, the oxidation of succinic acid was not modified, whereas the rate of oxidation of acetic acid formed transiently, was slightly lowered. In neutral and basic media, the oxidation of the carboxylate ions was greatly decreased. No leaching of ruthenium was observed, which means that the reaction was catalyzed by a heterogeneous catalytic system. However, the carbon support was partially oxidized, which limits the application of this catalytic system for the CWAO of acetic acid, which requires temperatures close to 200°C. 

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