Nuclear waste processing plants, zeolite

Zeolite Selective Catafytic Reduction Catafysts for NOjp Removal from Nuclear Waste Processing Plants... 

NOx (typically 1-3%), present in the stack gas of nuclear waste process plants, is removed in die WINCO Process by two primary reactors to 300-1000 ppm by selective catalytic reduction (SCR) with NH3 over a commercial zeolite catalyst at 300-500°C followed by reduction to low ppm levels in a third cleanup reactor. This study involved laboratory tests on advanced SCR zeolite catalysts, NC-301, ZNX, and Cu-ZSM-5, for the primary SCR reactors over a range of anticipated process conditions using gas mixtures containing 500-5000 ppm NO+NO2, 500-5000 ppm NH3, 1-2% CO, 14% O2, and 20% steam in He. All three catalysts have acceptable levels of performance, i.e. selectively reduce >80% the NOx with NH3 to N2 over the temperature range of 400-500°C at a space velocity of 30,000 h- The Cu-ZSM-5 catalyst is the most active and selective catalyst converting >95% NOx d NH3 (at 500 - 5000 ppm of each) to N2. 

Due to these properties zeolites are applied to numerous industrial processes as catalysts, selective adsorbents, ion exchangers as well as molecular sieves for the separation of n-paraffins, air constituents, the sweetening of natural gases, as ion exchanger in detergents and for the extraction of metal ions from waste water including those of radioactive isotopes from nuclear plants. 

---