Removal of gaseous benzene by a fixed-bed system packed with a highly porous metal-organic framework (MOF-199) coated glass beads

Abstract

The utility of nanomaterial adsorbents is often limited by their physical features, especially fine particle size. For example, a large bed-pressure drop is accompnied inevitably, if fine-particle sorbents are used in a packed bed system. To learn more about the effect of adsorbent morphology on uptake performance, we examined the adsorption efficiency of metal-organic framework 199 (MOF-199) in the pristine (fine powder) form and after its binding on to glass beads as an inert support. Most importantly, we investigated the effect of such coatings on adsorption of gaseous benzene (0.1-10 Pa) in a dry N₂ stream, particularly as a function of the amount of MOF-199 loaded on glass beads (MOF-199@GB) (i.e., 0,% 1%, 3%, 10%, and 20%, w/w) at near-ambient conditions (298 K and 1 atm). A 1% MOF-199 load gave optimal performance against a 0.1 Pa benzene vapor stream in 1 atm of N₂, with a two-to five-fold improvement (e.g., in terms of 10% breakthrough volume [BTV] (46 L atm [g.MOF-199)^-1], partition coefficient at 100% BTV (3 mol [kg.MOF-199]^-1 Pa^-1), and adsorption capacity at 100% BTV (20 mg [g.MOF-199]^-1 (areal capacity: 8.8 × 10^-7 mol m^-2) compared with those of 3%, 10%, and 20% loading. The relative performance of benzene adsorption was closely associated with the content of MOF-199@GB (e.g., 1% > 3% > 10% > 20%) and the surface availability (m² [g.MOF-199]^-1) such as 291 > 221 > 198 > 181, respectively. This study offers new insights into the strategies needed to expand the utility of finely powdered MOFs in various environmental applications.

Keywords: Coating; Glass bead; Isotherm modeling; Kinetic analysis; MOF-199; Pressure drop; VOCs removal.