Complex Rare-earth oxides leached from the rare-earth concentrate to prepare the catalyst for selective catalytic reduction of NO with NH3

Abstract

Different catalysts with complex Rare-earth oxides loaded on activated carbon were prepared and tested for the selective catalytic reduction (SCR) of NO with NH3 at low temperatures (150–300 °C). The Rare-earth concentrate in the bayan obo ore was used as raw material to leach valuable minerals using nitric acid and a hydrothermal method. The effects of the hydrothermal temperature and acid content on the dissolution rate of the Rare-earth concentrate were studied. In addition the denitration performance of the catalyst in the NH3-SCR reaction at low temperature was evaluated. The results showed that dissolution rate was best at a 15 mol/L nitric acid concentration and a hydrothermal temperature of 180 °C. The catalyst treated with 15 mol/L nitric acid had the best denitration performance, showing a denitration efficiency over 80% when temperature of reaction was between 200–300 °C. TG, SEM, XRD, XPS, NH3/NO-TPD methods were used to determine the physical structure and chemical properties of the catalyst. The results showed that high acidic content, an amorphous phase of the active material and the synergistic effect achieved when several different elements are present in the catalyst, provide proper condition for this type of materials to perform better in low temperatures.