Tackling the challenge of efficient VOCs removal across varied molecular sizes over zeolite adsorbent under humid conditions

Abstract

Efficient removal of volatile organic compounds (VOCs) with different molecular sizes over a single zeolite remains a great challenge, especially under humid conditions. Here, we introduced an innovative base leaching strategy to construct hierarchical pores within high-silica MFI zeolite on premise of maintaining a similar high micropore volume. The key points were the introduction of Al3+ and B3+ as pore directing agents into the base solution and meticulous regulation of the acid washing process. Because of the introduction of mesopores, the adsorption capacities for m-xylene increased by 16.1 times compared to that on conventional MFI adsorbent. Meanwhile, it exhibited comparable adsorption capacities for smaller VOCs, including dichloromethane and toluene. The adsorption capacities for ethanol showed a notable increase, accompanied by a decrease in the desorption temperature. This was attributed to the generation of additional silanol adsorption sites, as confirmed by 1H MAS NMR and in situ FT-IR spectra. Moreover, the optimal adsorbent presented good regeneration performance throughout the four dynamic adsorption–desorption cycling tests for all VOCs.