Trace removal of benzene vapour using double-walled metal–dipyrazolate frameworks

Abstract

In principle, porous physisorbents are attractive candidates for the removal of volatile organic compounds such as benzene by virtue of their low energy for the capture and release of this pollutant. Unfortunately, many physisorbents exhibit weak sorbate–sorbent interactions, resulting in poor selectivity and low uptake when volatile organic compounds are present at trace concentrations. Herein, we report that a family of double-walled metal–dipyrazolate frameworks, BUT-53 to BUT-58, exhibit benzene uptakes at 298 K of 2.47–3.28 mmol g−1 at <10 Pa. Breakthrough experiments revealed that BUT-55, a supramolecular isomer of the metal–organic framework Co(BDP) (H2BDP = 1,4-di(1H-pyrazol-4-yl)benzene), captures trace levels of benzene, producing an air stream with benzene content below acceptable limits. Furthermore, BUT-55 can be regenerated with mild heating. Insight into the performance of BUT-55 comes from the crystal structure of the benzene-loaded phase (C6H6@BUT-55) and density functional theory calculations, which reveal that C–H···X interactions drive the tight binding of benzene. Our results demonstrate that BUT-55 is a recyclable physisorbent that exhibits high affinity and adsorption capacity towards benzene, making it a candidate for environmental remediation of benzene-contaminated gas mixtures.

The Complexity of Comparative Adsorption of C6 Hydrocarbons (Benzene, Cyclohexane, n-Hexane) at Metal–Organic Frameworks

“…The low-pressure benzene sorption capacity of the top-3 MOFs here is lower than the top literature examples with the MOFs BUT-53 to BUT-58 with 193–256 mg g −1 (2.47–3.28 mmol g −1 ) at 298 K, <10 Pa (p p 0 −1 < 0.001) (Type-Ia isotherm) [ 77 ] or the benchmark materials MOF-5 with 802 mg g −1 at 295 K [ 78 ] or [Zn 4 O(bdc)(bpz) 2 ] with 561 mg g −1 at 298 K and p p 0 −1 = 0.1 [ 74 ] to which only MIL-101(Cr) with 607 mg g −1 at 293 K and p p 0 −1 = 0.1 comes close ( Table S2 , Figure 2 ).…”

Regulating the Porosity of Uranyl Phosphonate Frameworks with Quaternary Ammonium: Structure, Characterization, and Fluorescent Temperature Sensors

“…Structural design and porosity regulation are important, and several effective and practical strategies have been claimed for certain applications. , A literature survey was conducted to better understand the effects of quaternary ammonium template agents on the structure of the UPF system (Table S9). The comparison shows that using quaternary ammonium template agents is prone to synthesizing the 3D uranyl phosphonate framework structures.…”

Efficient Adsorption of Acetylene over CO2 in Bioinspired Covalent Organic Frameworks

“…C 2 H 2 , a widely used precursor and electronic gas, is produced via partial combustion of methane or steam cracking of hydrocarbons but with the impurity of cogenerated CO 2 . − Thus, C 2 H 2 /CO 2 separation is essential for high-purity C 2 H 2 production but highly challenging because of the similarities in their physical and chemical properties (Figure S20). Adsorptive separation using porous materials has shown great promise in reducing the energy penalty compared with energy-intensive processes such as the cryogenic distillation. ,− However, COFs are still underexplored for separating C 2 H 2 /CO 2 mixtures. , Promoted by the specific pore chemistry with abundant O atoms, the C 2 H 2 and CO 2 adsorption performances on NUS-71 and NUS-72 were investigated. Impressively, the C 2 H 2 uptakes can reach 42.4 and 48.0 cm 3 g –1 on NUS-71 and NUS-72, respectively, at 298 K. By comparison, the CO 2 uptakes are only 10.3 and 11.2 cm 3 g –1 on NUS-71 and NUS-72, respectively (Figure b,c).…”