Synergistic Multi-Template Synthesis of Cu-SSZ-13 at Ultra-Low Template Limit: A Step-by-Step Preaging Strategy for Exceptional NH3-SCR Performance

Abstract

The widespread commercialization of high-performance Cu-SSZ-13 catalysts for the selective catalytic reduction of NOx with NH3 (NH3-SCR) is severely restricted by the prohibitive cost of the conventional TMAdaOH structure-directing agent. Herein, we report a highly cost-effective, step-by-step preaging strategy to synthesize pure-phase, highly crystalline SSZ-13 zeolites under ultralow TMAdaOH conditions (TMAdaOH/SiO2 = 0.012). By systematically decoupling gel depolymerization from topological direction, this innovative preaging sequence leverages inexpensive short-chain amines (TEAOH and DEA) to drive thorough kinetic dissolution. The subsequent addition of bulky TMAdaOH and seeds provides precise thermodynamic guidance. This synergistic multitemplate approach completely suppresses the competitive mordenite (MOR) impurity, yielding a purely microporous chabazite (CHA) architecture with exceptional textural properties (BET surface area of 516 m2 g–1) comparable to conventional high-template syntheses. Structurally optimized, the resulting Cu-exchanged catalyst (Cu-S10-TtD-C2) features an ideal distribution of weak and medium-strong acid sites alongside a maximal density of isolated Cu2+ active centers. Consequently, it delivers outstanding NH3-SCR performance, sustaining >95% NOx conversion across a broad 250–600 °C window and increasing low-temperature activity by 25% compared to the unaged baseline. This study establishes a scalable and economically viable pathway for the industrial mass production of advanced Cu-SSZ-13 catalysts.