Enhanced hydrophobicity of modified ZIF-71 metal-organic framework for biofuel purification

Developing highly water-stable zeolitic imidazolate frameworks (ZIFs) for visible-light-driven photocatalytic hydrolysis is important and challenging. Herein, the Type II heterojunction catalyst Mn0.5Cd0.5S@ZIF-8 and its derivatives (including MCS@ZIF-8-Mn, MCS@ZIF-8-Br, and MCS@ZIF-8-MB) were successfully constructed using a facile strategy. Through dual postsynthetic ligand and cation exchange (PSE) treatments of Mn(Ac)2·4H2O and 4-bromo-1H-imidazole for ZIF-8, the hydrogen production efficiency of the MCS@ZIF-8-MB heterojunction catalyst can reach 5.450 mmol·g–1·h–1 and remain at 97.11% after 9 h of the stability test. Construction of heterojunctions can effectively improve the hydrogen production performance of Mn0.5Cd0.5S while maintaining excellent water stability. X-ray photoelectron spectroscopy results show that upon successful construction of the MCS@ZIF-8-MB heterojunction an interface forms between the surface of MCS and ZIF-8-MB, effectively weakening the photocorrosion of MCS. Density functional theory calculations also indicate that the induction of Mn can increase the electronic states of p and d orbitals near the Fermi level of ZIF-8, suggesting that Mn(II) attracts more electrons than Zn(II). This provides more powerful theoretical evidence for the electron cloud shift from the electron donor S2– to Mn2+.

Section: Resultssupporting

confidence: 78%

Highly Water-Stable and Efficient Hydrogen-Producing Heterostructure Synthesized from Mn_0.5Cd_0.5S and a Zeolitic Imidazolate Framework ZIF-8 via Ligand and Cation Exchange

Ding

Hong

Zhou

et al. 2023

“…MOFs are of particular interest as solid adsorbents due to their tunability and high adsorption capacities . In particular, zeolitic imidazolate frameworks (ZIFs), a family of metal imidazolate frameworks, have become one of the most studied families of MOFs due to their potential in applications such as catalysis, − gas storage, and separations. − Among the ZIF family of porous materials, ZIF-8, composed of zinc metal ions and 2-methylimidazole (HMIm) linkers, has been extensively studied for its gas adsorption properties. , Research into the stability of ZIF-8 as a solid sorbent material has demonstrated that it is stable at high temperatures, pressures, and pH. , The stability of ZIF-8 in water is temperature-dependent, exhibiting improved stabilities at higher temperatures . Additionally, the stability of ZIF-8 is impacted by the type of gases present.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Mechanisms that Govern Long-Term Stability of CO₂-Adsorbed ZIF-8-Based Porous Liquids

Hurlock

Christian

Fritzsching

et al. 2023

Porous liquids (PLs) based on the zeolitic imidazole framework ZIF-8 are attractive systems for carbon capture since the hydrophobic ZIF framework can be solvated in aqueous solvent systems without porous host degradation. However, solid ZIF-8 is known to degrade when exposed to CO 2 in wet environments, and therefore the long-term stability of ZIF-8-based PLs is unknown. Through aging experiments, the long-term stability of a ZIF-8 PL formed using the water, ethylene glycol, and 2-methylimidazole solvent system was systematically examined, and the mechanisms of degradation were elucidated. The PL was found to be stable for several weeks, with no ZIF framework degradation observed after aging in N 2 or air. However, for PLs aged in a CO 2 atmosphere, formation of a secondary phase occurred within 1 day from the degradation of the ZIF-8 framework. From the computational and structural evaluation of the effects of CO 2 on the PL solvent mixture, it was identified that the basic environment of the PL caused ethylene glycol to react with CO 2 forming carbonate species. These carbonate species further react within the PL to degrade ZIF-8. The mechanisms governing this process involves a multistep pathway for PL degradation and lays out a long-term evaluation strategy of PLs for carbon capture. Additionally, it clearly demonstrates the need to examine the reactivity and aging properties of all components in these complex PL systems in order to fully assess their stabilities and lifetimes.

“…However, in most cases, activated carbons in this application are not readily regenerable by physical or chemical means. Silica gel , and more recently metal–organic frameworks (MOFs) ,, have been shown to be regenerable sorbents for siloxanes when heated. Computational and experimental studies of MOFs by Gulcay-Ozcan et al showed that the large-pore MOF FOTNIN outperforms DUT-4 and MIL-101 in both adsorption capacity and regenerability under mild conditions …”

Section: Introductionmentioning

confidence: 99%

“…Among various separation technologies proposed to treat D4 in biogas, − adsorption technology using activated carbon as the adsorbent is the only one used industrially . However, in most cases, activated carbons in this application are not readily regenerable by physical or chemical means.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Simulations of Siloxane Adsorption in Metal–Organic Frameworks

Chng,

Sholl

2023

We present a transferable force field (FF) for simulating the bulk properties of linear and cyclic siloxanes and the adsorption of these species in metal−organic frameworks (MOFs). Unlike previous FFs for siloxanes, our FF accurately reproduces the vapor−liquid equilibria of each species in the bulk phase. The quality of our FF combined with the Universal Force Field using standard Lorentz−Berthelot combining rules for MOF atoms was assessed in a wide range of MOFs without open metal sites, showing good agreement with dispersion-corrected density functional theory calculations. Predictions with this FF show good agreement with the limited experimental data for siloxane adsorption in MOFs that is available. As an example of using the FF to predict adsorption properties in MOFs, we present simulations examining entropy effects in binary linear and cyclic siloxane mixture coadsorption in the large-pore MOF with structure code FOTNIN.