Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media
- Univ. of Georgia, Athens, GA (United States)
- Pacific Northwest National Lab., Richland, WA (United States)
The Hanford Waste Vitrification Plant (HWVP) is being designed by the U.S. Department of Energy to immobilize high-level nuclear waste. Simulants for the HWVP feed containing the major nonradioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO{sub 3}{sup 2-}, NO{sub 3}{sup -} and NO{sub 2}{sup -} were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO{sub 2}H{yields}H{sub 2}+/CO{sub 2} catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small-scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100{degree}C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO{sub 2}, H{sub 2}, NO, and N{sub 2}O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl{sub 3}.3H{sub 2}O, was found to be the most active catalyst for hydrogen generation from formic acid above nearly 80{degree}C in the presence of nitrite ion in accord with earlier observations. The apparent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is consistent with the approximate pseudo-first-order dependence of the hydrogen production rate on Rh concentration. 24 refs., 7 figs., 2 tabs.
- OSTI ID:
- 226676
- Journal Information:
- Environmental Science and Technology, Vol. 30, Issue 4; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
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