CO2 adsorption–desorption properties of zeolite beta prepared from OSDA-free synthesis

• OSDA-free beta with high CO2 adsorption–desorption capacity.
• OSDA-free beta exhibits high crystallinity, large pore volume and high Al content.
• OSDA-free beta exhibits different Al distribution compared to conventional beta.
• High CO2 adsorption ability in OSDA-free beta stemmed from its unique property.
• Reversible CO2 adsorption–desorption in OSDA-free beta over wide pressure region.

Recent research has demonstrated how the economically and environmentally benign organic structure-directing agent (OSDA)-free synthesis of zeolite beta—based on the seed-assisted method—exhibits superior properties in applications as antibacterial agents, catalysts and adsorbents in comparison with conventional zeolite beta. One possible way to take advantage of OSDA-free beta is to apply the material in energy-efficient capture of carbon dioxide (CO2) from a variety of large emission sources. For this reason, we have investigated the CO2 adsorption–desorption properties of OSDA-free beta for the first time. The results of elemental analysis, N2 and CO2 adsorption–desorption, evaluation of the isosteric heat of adsorption and solid-state NMR measurements have shown that OSDA-free beta exhibited higher crystallinity, larger pore volume and higher aluminum (Al) as well as sodium (Na) cation content with enhanced homogeneity in Al distribution within the *BEA framework as compared to the conventional TEA-directed beta synthesized using tetraethylammonium hydroxide (TEAOH). These unique properties of OSDA-free beta resulted in significant improvements of CO2 adsorption–desorption capability over a wide pressure region under moderate temperature in comparison with conventional zeolite beta.

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