Pulse radiolysis of 4,4'-bipyridyl aqueous solutions at elevated temperatures: Spectral changes and reaction kinetics up to 400 degrees C

作者：Lin MZ; Katsumura Y^*; He H; Muroya Y; Han ZH; Miyazaki T; Kudo H

来源：Journal of Physical Chemistry A, 2005, 109(12): 2847-2854.

DOI：10.1021/jp044590p

• Electron adducts
• Room temperature
• Spectral changes
• Supercritical water oxidation (SCWO)

The spectral changes as well as the reaction kinetics of the transient species of 4,4'-bipyridyl (4,4'-bpy) have been experimentally investigated by pulse radiolysis techniques up to 400 degrees C. The results show that the transient species such as OH adduct 4,4'-bpyOH(center dot), monoprotonated electron adduct 4,4'-bpyH(center dot), and doubly protonated electron adduct 4,4'-bpyH(2)(+) (center dot) have 15-20 nm blue shifts from room temperature to 400 degrees C. For a deaerated neutral solution of 4,4'-bpy in the presence of tert-butyl alcohol, ethanol, or NaCOOH, the doubly protonated electron adduct is the main transient species at room temperature. But at temperatures > 350 degrees C, a monoprotonated form, the N-hydro radical 4,4'-bpyH degrees, becomes predominant. Interestingly, at room temperature, CO2- could not efficiently react with 4,4'-bpy, but the reaction was accelerated with increasing temperature; at 350 degrees C, this reaction completed within 2,us. Using an alkaline solution (pH = 11.5) of 4,4'-bpy in the presence of tert-butyl alcohol, we studied the N-hydro radical 4,4'-bpyH center dot from room temperature to 400 degrees C at 25 MPa. An estimation of the temperature-dependent G(e(aq)(-)) at 25 MPa agrees with our previous result with methyl viologen as a scavenger.

• 出版日期2005-3-31