Ultrasound–Calcination Synergistic Control of (Ce, La)PO 4 Catalyst Structure for Enhanced Low‐Temperature NH 3 ‐SCR Performance

ABSTRACT In this study, (Ce, La)PO 4 catalysts were synthesized via an ultrasound‐assisted method. The effects of ultrasound duration and calcination temperature on the low‐temperature NH 3 ‐SCR performance were systematically investigated. The results indicated that the (Ce, La)PO 4 catalyst prepared with an ultrasound treatment time of 20 min and a calcination temperature of 400°C exhibited optimal denitrification efficiency, achieving a NO x conversion rate of 95.4% at 250°C. Characterization results revealed that under appropriate ultrasonic treatment and calcination conditions, the catalyst's pore structure and redox properties were significantly improved: The specific surface area reached 38.1105 m 2 /g, the total pore volume increased to 0.36616 cm 3 /g, and the average pore size expanded to 19.2 nm. Moreover, the catalyst surface exposed more Lewis and Brønsted acid sites, which enhanced the adsorption and desorption capacity of NH 3 . The presence of active intermediates such as –NH 2 , monodentate nitrite, and bidentate nitrite was identified, contributing to a notable improvement in the low‐temperature redox performance of the catalyst.