The study on using copper-containing mixed oxides as FCC reducing NO_x catalyst

Four Cu-Mg-Al-hydrotalcite-like materials with different Cu content were prepared by coprecipitation, after heat activation at 750 °C to be the mixed oxide catalysts. Under the FCC regenerator conditions and by using CO as the reductant, effects of composition of catalysts, reaction temperature, the presence of O₂, H₂O or SO₂ in the reaction system on reducing NO_x activity of catalysts were examined. The CO conversion under different reaction conditions was also investigated. The results showed that the activity-temperature-window of catalyst shifts to lower temperature with the increments of CuO content. The O₂ produced significant effects on different catalysts. The presence of H₂O gave rise to the reduction of the activity of catalysts in low temperature regime, whereas increase in high temperature regime. The SO₂-poisoning occured for all catalysts and could be regenerated partially by H₂ at 550 °C-The reaction of CO with O₂ took place first and then the reaction of CO with H₂O when CO, O₂ and H₂O coexisted.