Water oxidation systems

The oxidation with CPBA at 0 °C in CH2CI2 does not effect removal of tert-hutyl protecting groups [39]. Classic iodine/water oxidation system is not suitable, because it causes extensive tert-hutyl cleavage [39]. Finally tert-hutyl protective groups are removed by the action of trifluoroacetic acid TEA. This procedure is complementary to the one in Example 12. 

L.B. Kriksunov and A.A. Me Donald, Corrosion in Supercritical Water Oxidation Systems a Phenomenological Analysis, J. Electrochemical Society, 142, (1995), 4069. 

Kriksunov, L.B. and MacDonald, D.D., Understanding chemical conditions in supercritical water oxidation systems, ASME Heat Transfer Div., 317(2), 271-279, 1995a. 

Kriksunov LB, Macdonald DD. Corrosion in supercritical water oxidation systems—a phenomenological analysis. J Electrochemical Sci 1995 142(12) 4069, 4073. 

Light energy conversion and water-oxidation systems in photosynthesis... 

Other complex molecules in a homogeneous solution and the decomposition products would be solvated and stabilL by water molecules. This kind of degradative oxidation is probably prevented by the microheterogeneous environment imposed by the polymer membrane on the isolated metal complex entities. This work not only demonstrates realization of an efficient four-electron water oxidation system utilizing a polymer membrane, but also shows remarkable stabilization of the water oxidation catalyst against decomposition in a membrane. 

Residence time for supercritical water oxidation systems may be as short as several minutes at temperatures of 600 to 650°C. More than 99.9 percent conversion of EPA priority pollutants such as chlorinated solvents has been achieved in a pilot-scale plant with retention time less than 5 minutes. The system is limited to treatment of liquid wastes or solids less than 200 microns in diameter. Char formation during reaction may impact the oxidation time of the organics, while separation of inorganic salts during the process may be a problem. Typical materials for the reactor are Hastelloy C-276 and Iconel 625 (high nickel alloys), which can withstand high temperatures and pressmes and the corrosive conditions. 

Figure 12 Solubility and phase behavior in supercritical water oxidation systems, (a) O2-H2O at 250 bar (based on data from Refs. 99 and 100 at 250°C and above, other data from Ref. 101) (b) CO2-H2O at 250 bar (based on data from Ref. 102 at HO C and above, other data from Ref. 103 (c) Benzene-H2O at 250 bar (based on data from Ref. 104 below 100°C, Refs. 105 and 106 from 287-295 C, other data from Ref. 107) (d) Benzene-H2O at 100 bar (based on data from Ref. 104 up to 250°C, other data from Ref. 108). (e) NaCl-HoO at 250 bar (vapor phase compositions from Ref. 110 other data from Ref. Ill (f) NaCl-HoO at 100 bar (vapor phase compositions from Ref. 110, other data from Ref. Ill) (g) NaTStC-lCO at 250 bar (based on data from Ref. 116 at 320°C and above other data from Ref. 117) (h) Na2SO4-H2O at 100 bar (based on data from Ref. 116 at 320°C and above, other data from Ref. 117 and Ref. 118.)...

G. T. Hong, D. W. Ordway and V. A. Zilberstein, Materials Testing in Supercritical Water Oxidation Systems, First International Workshop on Supercritical Water Oxidation, Amelia Island, FL, February 1995. 

Applied Gas Solutions supply of gases and systems for small and medium users, either as packaged units or on-site generation, LoTOx and Loprox air and water oxidation systems ... 

Finding (Pueblo) GA-7. Corrosion remains a serious operating problem with the GATS supercritical water oxidation system. Failure to shut down in time to replace a perforated reactor liner could result in rapid corrosion of the high-pressure reactor shell. 

Latanision, R.W. and Shaw, R.W. (1993) Corrosion in supercritical water oxidation systems Workshop Summary. MIT-EL 93-006. 

There is a background of relevant knowledge arising from the nuclear power industry and the Energy Laboratory at the Massachusetts Institute of Technology (Boston) is a centre for supercritical water corrosion studies. A workshop on Corrosion in Supercritical Water Oxidation Systems was held in May 1993. A copy of the report subsequently produced is available from Professor Latanision at MIT. 

In a photo driven water oxidation system, like the one described above (eqs. 3-13), the efficiency of water oxidation depends on the intensity of the irradiation light and on the absorption of such light by the photosensitizer. For this reason, it is appropriate to compare oxygen production with photons absorbed by the photosensitizer referring to photochemical quantum yield of molecular oxygen produced, 0(02). 

Once described the role of each component in a photo-driven water oxidation system, their key properties will be highlighted in the next paragraphs, together with some significant examples of photosensitizers and catalysts. 

L. B. Kriksunov, D. D. Macdonald Corrosion in Supercritical Water Oxidation Systems A Phenomenological Analysis, J. Electrochem. Soc. 142, 1995, 4069. X.Y. Zhou, S.N. Lvov, X.J. Wei, L.G. Benning, D.D. Macdonald, Quantitative Evaluation of General Corrosion of Type 304 Stainless Steel in Subcritical and Supercritical Aqueous Solutions via Electrochemical Noise Analysis , Corrosion Science, 44 (2002) 841. 

---