3D-Printing Functional Ceramic for One-Step Fabrication of Pd/C Catalytic Reactor

• The method for constructing Pd@C catalytic reactor by coaxial 3D printing is reported for the first time. • The prepared Pd@C catalytic reactor has the special-shaped catalytic architecture. • This method combines the integrated fabrication, rapid prototyping and complex architecture forming. Catalysts are widely used in the chemical industry because of their environmental friendliness and low energy consumption. However, integrated fabrication of catalytic reactors (CRs) remains challenging. In this study, we propose the integrated manufacturing of a palladium-carbon (Pd/C) CR for the first time. The outer shell ink comprises Al 2 O 3 powder and aluminum dihydrogen phosphate (AP), whereas the inner core ink consists of activated carbon powder, AP, and polymethylmethacrylate (PMMA). By integrating with the coaxial 3D printing strategy, the Pd/C CR can be freeform-designed with different core thicknesses, lengths, and shapes (W-type, L-type, and U-type). Based on this, a CR with excellent catalytic properties was further developed by loading palladium (Pd) particles. Typically, the resultant Pd/C CR with a length of 2.5 cm exhibits a catalytic efficiency of up to 97.6 % after 60 min. This method of preparing Pd/C CR using coaxial 3D printing combines multimaterial 3D printing, integrated molding, and complex biomimetic structure fabrication. This offers a feasible and cost-effective solution that uses a simple fabrication process. Scheme 1. Schematic diagram of the preparation process of coaxial 3D printed Pd@C CR. The biological bone possesses the typical core-shell structure, which composed of cancellous bone and cortical bone. Inspired this, the Pd@C CR was one-step prepared by coaxial 3D printing. As illustrated in Scheme 1, the AP and Al 2 O 3 are employed as the shell ink, while the activated carbon, and PMMA are employed as the core ink. According to the principle of coaxial 3D printing, the green CR can be fabricated easily in an extruded way. Then, the resultant green CR was dried and sintered to obtain the porous core consisting of loose and porous activated carbon. Finally, Pd particles were loaded onto the activated carbon of the core of CR by impregnation to form the Pd@C CR with good catalytic performance. Integrating with coaxial 3D printing strategy, CR can be freeform designed with different core thicknesses, lengths, and various shapes (S-type, L-type, and U-type).