Optimizing the synthesis of Ag/γ‐Al₂O₃ for selective reduction of NOx with C₃H₆: Experiments and modelling

Abstract

Ag/γ‐Al2O3 is an effective catalyst for the selective reduction of NOx (SCR) using propylene as a reducing agent. The catalyst performance is greatly influenced by the synthesis procedure. Various methods for synthesis of Ag/γ‐Al2O3 are analyzed, and their performance is examined via packed bed reactor experiments in this work. An optimal one‐pot synthesis method, single‐step sol–gel (SSG) synthesis, is explored systematically. The SSG‐synthesized catalyst shows better performance than those prepared via wet impregnation. The influence of synthesis conditions, specifically pH, on the textural and morphological properties of the SSG‐synthesized Ag/γ‐Al2O3, and therefore the activity for hydrocarbon‐based SCR in a packed‐bed reactor, are analyzed using experiments and simulations. The optimized catalyst demonstrates excellent performance (90% NOx conversion) for NOx reduction under nominal operating conditions with a wide activity temperature window (300–600°C). The catalyst shows good time‐on‐stream performance and is effective at higher inlet oxygen concentrations and space velocities. A global kinetic model, which uses synthesis‐pH‐dependent parameters, is proposed, and its ability to predict the activities of these catalysts is validated.