Simultaneously Inhibiting SO2 Oxidation and Improving deNOx Activity over the VMo/Ti Catalyst by Ce and P Comodification

Abstract

Both improving the activity and reducing SO₃ emissions during selective catalytic reduction of NO_x by the NH₃ (NH₃–SCR) process over commercial V–Ti-based catalysts remain a challenge. Herein, Ce and P cooperatively modified the VMo/Ti catalyst to address this challenge. Within the temperature range of 250–350 °C, the optimal VMoCeP/Ti catalyst achieved a NO conversion of more than 95% and maintained a SO₂ oxidation ratio below 1.0%. The enhanced SCR activity of the modified catalyst could be attributed to the improvement in surface acidity and redox capacity by the addition of Ce and P, which would promote NH₃ adsorption and activation. Meanwhile, Ce and P coaddition could regulate the surface structure of vanadyl species from predominantly polymeric to a more dimeric form, which could also promote the SCR reaction. More importantly, except for the suppressed sulfation of vanadium species, both a lower proportion of polymeric vanadyl species and the strong interactions among V–Ce–P species could raise the energy barrier of the decomposition of sulfated vanadium species into SO₃, thereby inhibiting SO₂ oxidation. This work provided novel insights into developing efficient SCR catalysts with low SO₂ oxidation ratios for both the academic and industrial fields.