Selective catalytic reduction (SCR) is one of the main methods used to reduce NO_x 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 NO_x 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.

选择性催化还原（SCR）是用于减少NO的主要方法之一_X从柴油发动机排放。钒基催化剂因其良好的抗硫性和低成本而被广泛用于SCR。为了提高老化SCR的催化性能，采用实验和模拟方法研究了老化SCR状态，空速和氨氮比对NO _{x的影响。}转换效率。实验结果表明，老化后的SCR状态在低温和中温区域的催化性能与新鲜SCR的催化性能没有显着差异，并且在高温区域的降解显着。在低温和高温地区，空速是影响老化SCR的重要因素。增加氨氮比可以在一定程度上补偿SCR在低温和中温区域的老化效应。