Fabricating Mechanically Robust Binder‐Free Structured Zeolites by 3D Printing Coupled with Zeolite Soldering: A Superior Configuration for CO₂ Capture

Abstract

3D‐printing technology is a promising approach for rapidly and precisely manufacturing zeolite adsorbents with desirable configurations. However, the trade‐off among mechanical stability, adsorption capacity, and diffusion kinetics remains an elusive challenge for the practical application of 3D‐printed zeolites. Herein, a facile “3D printing and zeolite soldering” strategy is developed to construct mechanically robust binder‐free zeolite monoliths (ZM‐BF) with hierarchical structures, which can act as a superior configuration for CO 2 capture. Halloysite nanotubes are employed as printing ink additives, which serve as both reinforcing materials and precursor materials for integrating ZM‐BF by ultrastrong interfacial “zeolite‐bonds” subjected to hydrothermal treatment. ZM‐BF exhibits outstanding mechanical properties with robust compressive strength up to 5.24 MPa, higher than most of the reported structured zeolites with binders. The equilibrium CO 2 uptake of ZM‐BF reaches up to 5.58 mmol g −1 (298 K, 1 bar), which is the highest among all reported 3D‐printed CO 2 adsorbents. Strikingly, the dynamic adsorption breakthrough tests demonstrate the superiority of ZM‐BF over commercial benchmark zeolites for flue gas purification and natural gas and biogas upgrading. This work introduces a facile strategy for designing and fabricating high‐performance hierarchically structured zeolite adsorbents and even catalysts for practical applications.

Binderless zeolite monoliths production with sacrificial biopolymers

“…4d) monoliths, where soldered bridges can clearly be observed. Notably, such sintering is known to occur when zeolites are calcined in the presence of binding agents, such as bentonite or halloysite nanotubes and, therefore, was somewhat anticipated from literature [1,16,19]. This being stated, to the best of our knowledge, this is the first time these bridges have ever been observed between individual zeolite particles, especially between particles in a printed ceramic, meaning that the SEM micrographs represent a novel piece of information pertaining to the physiomechanical properties of structured zeolites.…”

“…In a pioneering work in 2016 [1], our group formulated zeolite 13X and 5A monoliths with 90 wt% loading by binding the commercial powders to bentonite clay through 3D printing technique. More recently, Wang et al [19] surpassed the 90 wt% threshold by solvothermally bridging commercial zeolite particles, colloidal silica, and halloysite nanotubes after printing to form 100% binderless NaX zeolite monoliths. Nevertheless, although this technique did produce a binderless zeolite structure through 3D printing, the solvothermal step was time-intensive and required extensive optimization to coordinate the various components.…”

“…These samples are noted as 13X 1% , 13X 2.5% , and 13X 5% , respectively. Here, it should be noted that we selected the monolithic geometry as to demonstrate this technique because of its relevance in industrial processes and because of its use in previous works for 3D printing [1,16,19]. CO 2 , CH 4 , and N 2 adsorption isotherms were collected at 25 • C from 0 to 1 bar for the calcinated monoliths and parent powders, to demonstrate any differences between adsorption capacities, where the CO 2 /CH 4 and CO 2 /N 2 selectivities were calculated by the previously-detailed ideal adsorption solution theory (IAST) method [28].…”

State of the Art and Perspectives of Hierarchical Zeolites: Practical Overview of Synthesis Methods and Use in Catalysis

“…Recently, binder-free zeolite monoliths featuring hierarchical structures were obtained using 3D-printing technology. [387] Such new technology will be a good method for precise control of the proportion, connectivity, and distribution of micro-, meso-, and macropore systems. The molecule diffusion kinetic within various hierarchical systems significantly differs and consequently affects the catalytic performance.…”

Reinforced 3D Composite Structures of γ-, α-Al2O3 with Carbon Nanotubes and Reduced GO Ribbons Printed from Boehmite Gels

“…In the case of 3D-printed ceramics, the use of fibers is beginning to be explored, displaying significant results in improving the flexural and compressive strength of the scaffolds. Some examples that demonstrate this mechanical enhancement are the manufacturing of reinforced SiC/carbon fiber [ 15 ] and tricalcium phosphate/boron nitride nanotubes [ 16 ] composites by selective laser sintering, the fabrication of aligned carbon fibers into silica composites by stereolithography [ 17 ], and zeolite/halloysite nanotubes structures obtained by DIW [ 18 ].…”