Study on the performance of catalyst for removing nitrogen oxides from regenerated flue gas of petroleum catalytic cracking

Objective The nitrogen oxides (NO_x) in the regenerated flue gas of petroleum catalytic cracking need to be removed by NH₃-selective catalytic reduction (NH₃-SCR) denitration technology. However, the traditional vanadium-based catalysts exhibit poor low-temperature activity and are prone to poisoning and deactivation due to the influence of SO₂, thereby shortening their service life. Therefore, it is necessary to develop denitration catalysts with excellent low-temperature activity and high SO₂ poisoning resistance.

Method A novel Co-doped Cr₂O₃/Al₂O₃ catalyst was prepared, and the effect of Co doping content on the low-temperature activity and SO₂ poisoning resistance of the Cr₂O₃/Al₂O₃ catalyst was investigated.

Result Firstly, catalytic activity test results showed that doping Co could significantly enhance the low-temperature activity of the Cr₂O₃/Al₂O₃ catalyst. Among them, the catalyst with a Co doping molar fraction of 20% exhibited the highest activity, which achieved a NO_x conversion rate of 90% at 116 °C, along with good SO₂ poisoning resistance. Secondly, catalyst characterization results indicated that doping Co into the catalyst increased the number of acidic sites, Cr⁶⁺ species, and surface-adsorbed oxygen species, thereby improving the selective catalytic reduction (SCR) reaction rate.

Conclusion The developed Co-modified Cr-based denitration catalyst can achieve denitration at low-temperature, which is beneficial for the removal of nitrogen oxides in the regenerated flue gas of petroleum catalytic cracking units.