High-Efficiency Silane Utilization in Amine-Modified Adsorbents for Direct Air Capture through Interconnected Three-Dimensional Pores.

Economic synthesis of amine-modified solid adsorbents is pivotal for the global-scale direct air capture (DAC) technologies required to realize net-zero emissions. To address the problems of the traditional reflux method using excessively costly amino silane, we propose introducing silane by impregnation into mesoporous silica with interconnected three-dimensional pores. X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption-desorption, transmission electron and scanning electron microscopies, magic-angle spinning nuclear magnetic resonance, and elemental analysis identified the spatial distribution of amino silane in the materials with different loading levels. The results of structure characterization and a comparison with a reference experiment (using a porous support with one-dimensional pores and/or the conventional reflux method) revealed that the proposed strategy provided a uniform amine distribution, together with a high utilization efficiency of the amino silane. We also demonstrate that the obtained material has a high adsorption capacity and good recycling stability comparable to those of the previously reported amino silane modified adsorbents under simulated DAC conditions.