Recent advances in improving SO2 resistance of Ce-based catalysts for NH3-SCR: Mechanisms and strategies

Selective catalytic reduction with ammonia (NH3-SCR) technology is an effective process for industrial flue gas denitrification. Ce-based catalysts are widely studied due to their excellent redox properties and superior oxygen storage and release capacity (OSC). However, the unavoidable presence of SO2 and H2O in the coal-fired flue gas leads to their limitations in the application of denitrification technology. SO2 poisoning not only causes the formation of metal sulfates, but its synergistic interaction with H2O also results in the deposition of ammonium sulfate species. All this leads to severe deactivation of Ce-based catalysts in NH3-SCR. The development of Ce-based catalysts with excellent sulfur and water resistance is an urgent requirement for SCR technology. This review elucidates the poisoning mechanism of SO2, and analyzes the effects of metals/non-metals modification and structural optimization on the anti-SO2 performance of Ce-based catalysts. This provides the reference and guidance for the subsequent development of Ce-based catalysts resistance to SO2.