Improvement of Ce[sbnd]Nb doping on low-temperature catalytic activity of a VOx-based catalyst for NH₃–SCR reaction

A series of VxCeNbTi catalysts were prepared using a wet impregnation method for selective catalytic reduction (SCR) of NO by NH₃. The influence of Ce[sbnd]Nb addition to VTi was investigated in terms of active sites and acidity. The correlation between surface properties, catalyst structure, and performance with the addition of Ce and/or Nb was demonstrated. The composition of VCeNbTi species, surface acid properties, and redox behavior were studied. Results showed that the addition of 2Ce[sbnd]Nb to VTi increased NH₃ adsorption, and brought about positive changes in Brönsted acid sites and composition of surface species. Nbⁿ⁺ mainly existed as typical Nb₂O₅ species, forming abundant acid sites and defects on the catalyst surface, closely related to the distribution of VOx species which varied with ceria content. The presence of 2Ce[sbnd]Nb induced electron redistribution, promoting oxygen defects and reactive oxygen species formation due to the occupancy of high Vⁿ⁺ (n = 4, 3). The increased proportion of Vⁿ⁺ (n = 4, 3) improved catalytic activity by generating active groups on the catalyst surface. The introduction of 2Ce[sbnd]Nb enhanced SCR performance with increased NO₂ generation. V2CeNbTi exhibited improved resistance in the presence of SO₂/H₂O, crucial for high-performance and durable catalysis.