Coaxial 3D Printing of Zeolite-based Core-shell Monolithic Cu-SSZ-13@SiO2 Catalysts for Diesel Exhaust Treatment.

Abstract

Core-shell catalysts with functional shells could increase the activity and stability of the catalysts in selective catalytic reduction with ammonia (NH3 -SCR) for diesel exhaust NOx treatment. However, the conventional approaches based on the multistep fabrication for core-shell structures encounter persistent restrictions regarding the strict synthesis condition and limited design flexibility. Herein, a facile coaxial 3D printing strategy has been for the first time developed to construct zeolite-based core-shell monolithic catalysts with interconnected honeycomb structures, in which the hydrophilic non-compact silica serves as shell and Cu-SSZ-13 zeolite acts as core. Compared to Cu-SSZ-13 monolith suffered from the interfacial diffusion, the SiO2 shell layer can increase the accessibility of active sites over Cu-SSZ-13@SiO2 , resulting in a 10-20% higher NO conversion at the 200-550 °C under 300,000 cm3 g-1 h-1 . Meanwhile, a thicker SiO2 shell enhances the hydrothermal stability of the aged catalyst by inhibiting the dealumination and the formation of CuOx . Other representative monolithic catalysts with different topological zeolites as shell and diverse metal oxides as core can be also realized by this coaxial 3D printing. This strategy allows multiple porous materials to be directly integrated, which allows for flexible design and fabrication of various core-shell monolithic catalysts with customized functionalities. This article is protected by copyright. All rights reserved.