Separation of Methane/Ethylene Gas Mixtures Using Wet ZIF-8

Carbon dioxide separation and capture by adsorption: a review

Rising adverse impact of climate change caused by anthropogenic activities is calling for advanced methods to reduce carbon dioxide emissions. Here, we review adsorption technologies for carbon dioxide capture with focus on materials, techniques, and processes, additive manufacturing, direct air capture, machine learning, life cycle assessment, commercialization and scale-up.

In-situ growth of Cu(2-methylimidazole imidazole)2 on Cu2O polyhedrons for high-performance potassium-ion batteries

In this work, Cu₂O/Cu(2-MeIm)₂ core-shell structure was designed and used as an anode for potassium-ion batteries. The Cu₂O core not only ensured a high energy density through surface redox reactions, but also served as a copper-ion reservoir to keep the stability of skeleton structure of Cu(2-MeIm)₂ shell during electrochemical process. The Cu(2-MeIm)₂ shell, in turn, not only provided high power through rapid K⁺ adsorption/desorption, but also acted as an artificial solid electrolyte interphase layer and accommodated volumetric change during K⁺ intercalation/de-intercalation. The as-designed composite material was studied by X-ray diffraction, thermo gravimetric, Fourier transform infrared, nitrogen adsorption-desorption, X-ray photoelectron spectroscopic and electron microscopic characterizations. As an anode for potassium-ion batteries, it was galvanostatically discharged and charged to study its electrochemical properties, such as Coulombic efficiency, capacity retention and rate performance, and cyclic voltammetry curves were also tested to reveal its K-storage mechanism.

Properties of Cobalt- and Nickel-Doped Zif-8 Framework Materials and Their Application in Heavy-Metal Removal from Wastewater

Heterometallic zeolite imidazole framework materials (ZIF) exhibit highly attractive properties and have drawn increased attention. In this study, a petal-like zinc based ZIF-8 crystal and materials doped with cobalt and nickel ions were efficiently prepared in an aqueous solution at room temperature. It was observed that doped cobalt and nickel had obviously different effects on the morphology of ZIF-8. Cobalt ions were beneficial for the formation of ZIF-8, while addition of nickel ions tended to destroy the original configuration. Then we compared the absorption ability for metal ions between petal-like ZIF-8 and its doped derivatives with anion dichromate ions (Cr₂O₇^2-) and cation copper ions (Cu²⁺) as the absorbates. Results indicated that saturated adsorption capacities of Co@ZIF-8 and Ni@ZIF-8 for Cr₂O₇^2- reach 43.00 and 51.60 mg/g, while they are 1191.67 and 1066.67 mg/g for Cu²⁺, respectively, which are much higher than the original ZIF-8 materials. Furthermore, both the heterometallic ZIF-8 materials show fast adsorption kinetics to reach adsorption equilibrium. Therefore, petal-like ZIF-8 with doped ions can be produced through a facile method and can be an excellent candidate for further applications in heavy-metal treatment.

Enrichment of Hydrogen from a Hydrogen/Propylene Gas Mixture Using ZIF-8/Water-Glycol Slurry

In this work, zeolitic imidazolate framework-8 (ZIF-8), a subclass of metal organic frameworks (MOFs), was dispersed in a water-glycol solution to form a porous slurry. Using this porous slurry, a tail gas mixture containing hydrogen/propylene was separated. Experiments were performed to investigate the effects of using only the solid ZIF-8 material, a ZIF-8/water slurry, a ZIF-8/glycol slurry, or a ZIF-8/water-glycol slurry on the selectivity of the separation. The experimental results show that the slurry made from ZIF-8/water-glycol (20%) achieves good gas separation. The respective influences of the solid content, initial pressure, and temperature on the separation performance were also investigated in detail. We found that lower temperature, a ZIF-8 mass fraction of 20 wt %, and a higher operation pressure are suitable for the recovering of hydrogen from a H2/C3H6 mixture. The selectivity of C3H6 over H2 reaches 128 at 680 kPa initial pressure. The slurries were completely reusable for at least three cycles. The structure of the ZIF-8 material was not altered after repeated separation, meaning the material can likely be reused more than three times on an industrial scale.