Design and synthesis of core-shell structured meso-Cu-SSZ-13@mesoporous aluminosilicate catalyst for SCR of NOx with NH3: Enhancement of activity, hydrothermal stability and propene poisoning resistance

•A core-shell structured meso-Cu-SSZ-13@MAS catalyst was firstly prepared.•The enhancement of SCR activity, hydrothermal stability and poisoning resistance was achieved.•Mesoporous structure was in favor of the increase of active Cu species.•High hydrothermal stability was indeed correlated with the MAS shell.•High propene poisoning resistance was linked to fewer active sites for propene oxidation reaction.

A core-shell structured composite material with a mesoporous aluminosilicate (MAS) shell and mesopore-containing SSZ-13 (meso-SSZ-13) core was first synthesized by combining controlled desilication with subsequent self-assembly. The corresponding catalyst was subsequently prepared by a copper ion-exchange method. This catalyst can simultaneously solve three major problems existing in the previous Cu-SSZ-13 catalyst for NOx emission control from diesel engine exhaust, i.e., low temperature activity, hydrothermal stability and propene poisoning resistance. In comparison with Cu-SSZ-13, the meso-Cu-SSZ-13@mesoporous aluminosilicate (meso-Cu-SSZ-13@MAS) catalyst showed higher SCR activity across the entire temperature range. This increase was observed due to increasing the amount of active Cu species (isolated Cu2+ ions) and fewer pore diffusion limitations. The MAS shell with a “concrete with crushed stone”-like mesostructure could prevent the dealumination of meso-SSZ-13 core effectively, and therefore enhanced the hydrothermal stability of the meso-Cu-SSZ-13@MAS catalyst. Additionally, meso-Cu-SSZ-13@MAS exhibited higher hydrocarbon poisoning resistance because its external surface has fewer active sites for propene oxidation reaction.

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