Simulation on catalytic performance of fresh and aged SCR catalysts for diesel engines

Selective catalytic reduction (SCR) is one of the main methods used to reduce NOx emissions from diesel engines. Vanadium-based catalysts are widely used in SCR because of their good sulfur resistances and low costs. In this paper, for improving the catalytic performance of aged SCR, experimental and simulation methods were used to study the effects of the aged SCR state, space velocity, and ammonia-to-nitrogen ratio on the NOx conversion efficiency. The experimental results showed that the catalytic performances of the aged SCR state in the low- and medium-temperature regions were not significantly different from that of the fresh SCR, and the degradation in the high-temperature region was significant. In the low- and high-temperature regions, space velocity was an important factor affecting the aged SCR. Increasing the ammonia-to-nitrogen ratio could compensate for the effect of the SCR aging in the low- and medium-temperature regions to some extent.