Improved hydrothermal stability of Cu-SSZ-13 by SAPO-34 modification: Framework stability and inter-particle migration

•SAPO-34 addition improves the hydrothermal stability of Cu-SSZ-13 via ball milling.•SSZ-13 framework is well protected by formation of P-O-Al bonds at the interface.•More Cu2+ and strong Brønsted acid sites are reserved in the aged composite catalyst.•Aggregation to CuO crystallites and CuAl2O4 are reduced by SAPO-34 modification.•Migration into ion-exchange sites of SAPO-34 neighbors reactivates detached copper.