Core-shell deAlY@SiO2 composite: A superior adsorbent for toluene capture under humidity condition.

The high hydrophobic surfaces (internal and external) resulted from reduced hydroxyl groups, elevated framework Si/Al ratio and constructed SiO 2 shell, acting as barriers for shielding water in wet VOCs, and the purified VOCs can be fully adsorbed by the de AlY zeolite core due to the weakened competitive adsorption of water vapor. [Display omitted] • Reformation of Y zeolite framework due to the deposition of Si-species is discovered. • Not only constructing the mesopore shell, Si-species also entering core zeolite framework. • Reduced hydroxyl, elevated Si/Al ratio and fabricated SiO 2 shell offer hydrophobic surfaces. • Hydrophobic external and internal surfaces act as barriers for shielding water in wet VOCs. • Mesoporous SiO 2 shell also builds an express way that contributes to mass transfer. Y zeolite has been regarded as an effective adsorbent in removal of volatile organic compounds (VOCs). However, the low Si/Al ratio causes Y zeolite to preferentially adsorb water when dealing with wet VOCs, which limits its practical application. In present work, Y zeolite was first dealuminated treated by steaming and acid etching, and then the obtained de AlY was used as cores to prepare de AlY@ n SiO 2 core–shell composites. The shell layer thickness in the as-prepared core–shell composites was adjusted by controlling the hydrolysis of tetraethoxysilane (TEOS). The Si-species yielded from the hydrolysis of TEOS not only fabricated the mesopore shell directed by CTA+, but also entered the zeolite framework by polycondensation with the adjacent hydroxyl (silicon hydroxyl of (SiO) 3 Si(OH) species or aluminum hydroxyl of penta-coordinated aluminum caused by steaming and acid etching) in the defect sites of the core de AlY. During the adsorption of dry toluene, the as-synthesized composite displayed an adsorption capacity superior to mesopore SiO 2 while inferior to de AlY. When toluene and water molecules competed for the adsorption sites, the core–shell composite preferred to adsorb the former because of the greatly reduced sensitivity to the presence of water vapor. Under 55 % and 83 % relative humidity, the core–shell de AlY@ n SiO 2 (n < 1.5) respectively had 4.2 and 9.0 times higher toluene adsorption than the de AlY. The mesopores in the SiO 2 shell was conducive to a fast mass transfer, the high hydrophobic surfaces (internal and external) resulted from reduced hydroxyl content, elevated framework Si/Al ratio and constructed SiO 2 shell, contributed to shielding water, which promoted toluene in the wet VOCs to be adsorbed efficiently by the de AlY zeolite core. [ABSTRACT FROM AUTHOR]