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 can increase the activity and stability of the catalysts in selective catalytic reduction of NOx with ammoniax. However, the conventional approaches based on multistep fabrication for core–shell structures encounter persistent restrictions regarding strict synthesis conditions and limited design flexibility. Herein, a facile coaxial 3D printing strategy is for the first time developed to construct zeolite‐based core–shell monolithic catalysts with interconnected honeycomb structures, in which the hydrophilic noncompact silica serves as shell and Cu‐SSZ‐13 zeolite acts as core. Compared to a Cu‐SSZ‐13 monolith which suffers 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 at200−550 °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 the 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.

Selective catalytic reduction of NOx with NH3 over copper-based catalysts: recent advances and future prospects

“…9a). 120 In contrast, since pure Cu-SSZ-13 zeolites were limited by the interfacial diffusion, the interaction between SiO 2 shells and Cu-SSZ-13 cores increased the accessibility of Cu active centers on Cu-SSZ-13@SiO 2 (Fig. 9b), leading to superior de-NO x performance (Fig.…”

“…Notably, selective catalytic reduction with ammonia (NH 3 -SCR) is widely employed to remove NO x due to the advantages of wide operating temperature, superior redox properties and high thermodynamic stability. 18–22 In particular, in the real application of diesel vehicle systems (Fig. 1a), the NH 3 -SCR unit is located at the downstream position of the system comprising multiple processing units.…”

Copper-exchanged SUZ-4 zeolite catalysts for selective catalytic reduction of NOx

“…[1][2][3][4][5] Particularly, the Cu-SSZ-13 zeolite has been commercialized and employed in diesel vehicles due to its good hydrothermal stability and catalytic activity. [6][7][8][9][10][11] However, it is faced with the challenge of high-cost organic template of N,N,Ntrimethyl-1-adamantylammonium hydroxide (TMAdaOH). 12 To deal with the above challenge, various low-cost organic templates have been proposed to synthesize SSZ-13 zeolites.…”

“…1–5 Particularly, the Cu-SSZ-13 zeolite has been commercialized and employed in diesel vehicles due to its good hydrothermal stability and catalytic activity. 6–11 However, it is faced with the challenge of high-cost organic template of N , N , N -trimethyl-1-adamantylammonium hydroxide (TMAdaOH). 12…”

Synthesis and catalytic oxidation performance of gold@mesoporous carbon core-shell and yolk-shell hollow nanomaterials

“…. 然而, 大多数核壳材料具有相对致密的壳层, 这可 能会覆盖活性位点和/或限制扩散过程, 制约了其在催 化等领域的应用 [8,9] . 而多孔结构的壳层则能够提供通 道, 使反应物分子能够扩散进入内核, 特别是介孔结构 壳层, 其较大的介孔孔道能增强尺寸较大的分子与内 核金属接触性 [10~13] .…”