Terephthalate Metal Organic Framework Research Articles

High-performance and long-term thermal management material of MIL-101Cr@GO

Here, we demonstrate a breathing-like passive thermal management material based on moisture adsorption and desorption of graphene oxide (GO) modified chromium (III) terephthalate metal organic framework (MIL-101Cr), which breaks the limitation of latent heat limitation of common phase change materials and is highly desirable for long-term heat dissipation of batteries and chips. Nanoscale MIL-101Cr (50–100 nm) in-situ grown on the surface of GO (MIL-101Cr@GO) were prepared using a simple hydrothermal reaction method. In which, the MIL-101Cr acts as moisture adsorbent thus enables us to realize efficient heat dissipation through its moisture adsorption and desorption; while the GO acts as the nucleating agent for the growth of MIL-101Cr thus increases the nucleation rate and reduces the grain size of MIL-101Cr. As a result, the MIL-101Cr@GO shows high specific surface area and pore volume than that of pristine MIL-101Cr, resulting in higher moisture adsorption capacity and adsorption rate. In particular, the thermal management material MG6 (composed of MIL-101Cr and 6 wt% GO) shows a high moisture adsorption capacity of 1.391 g g−1 (i.e., 1 g absorbent can absorb 1.391 g moisture), 35.44% higher than that of MIL-101Cr. The thermal management material MG6 achieves 9.0 °C temperature drop under 95% relative humidity for a ceramic heater with a heating power of 4 W (similar to a typical Li-ion battery), and keep at ∼43.2 °C for at least 2 h. In addition, the material MG6 can remain 95% moisture adsorption capacity after 144 h of continuous operation, showing good thermal management performance and stability.

Synthesis, characterization of Lanthanum (III) / Terephthalate metal-organic framework, and potential use for Removal of anionic and cationic exchange contaminants

Synthesis, characterization of Lanthanum (III) / Terephthalate metal-organic framework, and potential use for Removal of anionic and cationic exchange contaminants

Graphene oxide incorporated amino‐functionalized iron terephthalate composite as a heterogeneous Fenton‐like catalyst

AbstractAmino‐functionalized iron terephthalate metal–organic framework (NH2‐MIL‐88B) has been studied for its adsorption and catalytic properties due to its high surface area and unique topological architecture. Functionality of the material can be improved through surface modification to increase active sites for the targeted applications. In this study, graphene oxide (GO) was incorporated to the NH2‐MIL‐88B material to obtain composite with improved adsorption and catalytic properties. The results showed that GO/NH2‐MIL‐88B in dark (as GO/NH2‐MIL‐88B/Dark system) was capable to adsorb 28.1% of methylene blue (MB) in water, which is about twice the adsorption of MB by the NH2‐MIL‐88B material in dark (as NH2‐MIL‐88B/Dark system). Furthermore, with the presence of hydrogen peroxide (H2O2), the GO/NH2‐MIL‐88B composite in dark condition (as GO/NH2‐MIL‐88B/H2O2/Dark) and the GO/NH2‐MIL‐88B composite under ultraviolet‐A (UV‐A) irradiation (as GO/NH2‐MIL‐88B/H2O2/UV‐A) have shown promising Fenton‐like behavior, which have removed 72.2% and 92.3% of MB in water, respectively. The removal of MB was well fitted to the Langmuir–Hinshelwood pseudo‐first order kinetics model with the reaction rate constant, k1 = 0.0221 min−1 and k1 = 0.0426 min−1 for GO/NH2‐MIL‐88B/H2O2/Dark and GO/NH2‐MIL‐88B/H2O2/UV‐A system, respectively. This study implies that the GO/NH2‐MIL‐88B composite can be a good catalyst for the heterogeneous Fenton‐like degradation of cationic pollutants in water.

Efficient one‐pot synthesis of polyhydroquinoline derivatives through the Hantzsch condensation using IRMOF‐3 as heterogeneous and reusable catalyst

AbstractA mesoporous Zn‐based 2‐amino terephthalate metal organic framework (IRMOF‐3) catalyst was prepared using the solvothermal method. The synthesized catalyst was characterized by powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), energy‐dispersive spectroscopy (EDAX), and Brunauer–Emmett–Teller surface area analysis (BET). It was applied as an effective heterogeneous catalyst for the synthesis of one‐pot four‐component polyhydroquinoline derivatives via the Hantzsch condensation. The present method offers several advantages over other reported methods such as easy separation, mild reaction condition, and excellent yield of desired product. Furthermore, the catalyst can be reused without loss in activity.

Encapsulation of silicotungstic acid into chromium (III) terephthalate metal–organic framework for high proton conductivity membranes

Heteropoly acids have attracted great attention as potential solid-state proton-conducting materials owing to their high proton conductivity of 10–2 S cm−1 at room temperature. However, the proton conductivity can be significantly reduced under operating conditions due to the leaching of water molecules out of the acid Keggin structure. In the present study, silicotungstic acid (SiWA) was encapsulated in the mesoporous structure of the chromium (III) terephthalate metal–organic framework (MIL-101) in an attempt to prevent water loss and preserve proton conductivity. This hybrid material was then shaped into a membrane with the aid of polyvinyl alcohol (PVA). This approach of SiWA encapsulation with PVA addition to form a membrane proved to be successful as the proton conductivity of the resulting membranes was found to be of 2.4 × 10–2 S cm−1 at 25 °C and 25% RH. Under low levels of hydration, when the membrane was dried at 80 °C, the proton conductivity still remained high (1.9 × 10–2 S cm−1). This improved proton conductivity is believed to be the result of the continuous channels for facile proton transport created through the immobilisation of the heteropoly acid within the MIL-101 framework.

Metal-organic framework/zeolite nanocrystal/polyvinylidene fluoride composite ultrafiltration membranes with flux/antifouling advantages

In this study, hydrophilic zirconium 1,4-dicarboxybenzene (UiO-66) and chromium (III) terephthalate (MIL-101) metal-organic frameworks (MOFs) and faujasite (FAU) zeolite nanocrystals were synthesized successfully and incorporated into polyvinylidene fluoride (PVDF) matrix as nanofillers to fabricate mixed matrix membranes (MMMs) via non-solvent induced phase separation (NIPS) process. The effects of casting solution temperature and casting speed as two important factors in membrane fabrication via phase inversion method on performance and structure of the neat PVDF membrane were investigated. Then, various contents of the synthesized nanofillers were loaded into the PVDF matrix and the effects of the synthesized nanofillers on hydrophilicity, pure water flux (PWF), morphology and antifouling properties of the fabricated MMMs were explored. Antifouling studies were also performed using Bovine serum albumin (BSA). The obtained results demonstrated that incorporation of the synthesized nanofillers into the PVDF membrane has positive effect on performance and structure of the fabricated MMMs and the MMM containing 0.1 wt% MIL-101 showed the best performance with water flux of 360 LMH, BSA rejection of 100%, irreversible fouling of 22.2% and flux recovery ratio of 77.7%. This work highlighted the potential application of the MOFs as effective nanofillers for MMM fabrication.

An Effective Hybrid Heterogeneous Catalyst to Desulfurize Diesel: Peroxotungstate@Metal-Organic Framework.

A peroxotungstate composite comprising the chromium terephthalate metal–organic framework MIL-101(Cr) and the Venturello peroxotungstate [PO4{WO(O2)2}4]3− (PW4) has been prepared by the impregnation method. The PW4@MIL-101(Cr) composite presents high catalytic efficiency for oxidative desulfurization of a multicomponent model diesel containing the most refractory sulfur compounds present in real fuels (2000 ppm of total S). The catalytic performance of this heterogeneous catalyst is similar to the corresponding homogeneous PW4 active center. Desulfurization efficiency of 99.7% was achieved after only 40 min at 70 °C using H2O2 as an oxidant and an ionic liquid as an extraction solvent ([BMIM]PF6, 2:1 model diesel/[BMIM]PF6). High recycling and reusing capacity was also found for PW4@MIL-101(Cr), maintaining its activity for consecutive oxidative desulfurization cycles. A comparison of the catalytic performance of this peroxotungstate composite with others previously reported tungstate@MIL-101(Cr) catalysts indicates that the presence of active oxygen atoms from the peroxo groups promotes a higher oxidative catalytic efficiency in a shorter reaction time.

Enhanced Photocatalytic Degradation of MB Under Visible Light Using the Modified MIL-53(Fe)

In this report, we focus on the modification of iron terephthalate metal–organic framework (MIL-53(Fe)) by soaking in H2O2 solution and its mechanism. The structure of MIL-53(Fe) before and after the modification were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and N2 adsorption–desorption isotherms. The XRD results showed that the material structure changed to amorphous phases and the photocatalytic efficiency was improved after modified by H2O2. The MIL-53 (Fe, H2O2) nanoparticles about 100–300 nm in size was successfully prepared and confirmed by SEM images. In term of UV–Vis DRS results, the absorption spectrum of modified MIL-53(Fe) shifted to higher wavelength and its band gap energy is estimated about 2.2 eV, which is significantly lower than the bandgap value of the conventional material. The impact of the modification on the photocatalytic efficiency was investigated by methylene blue (MB) degradation experiments and photoluminescence (PL) spectroscopy. MB was completely decomposed within 30 min by modified MIL-53(Fe) under optimal conditions. The reaction parameters that affect MB degradation by the as-prepared catalyst were also investigated, including the pH solution, catalyst and H2O2 dosage.

Iron terephthalate metal–organic framework (MOF-235) as an efficient adsorbent for removal of toluidine blue dye from aqueous solution using Box–Behnken design as multivariate optimization approach

In this work, iron terephthalate metal–organic framework (MOF-235) as an efficient adsorbent has been synthesized and employed for toluidine blue (TB) removal in a batch system. The adsorbent was characterized by Fourier-transform infrared, scanning electron microscopy, and powder X-ray diffraction. The effects of operational parameters including pH, initial dye concentration (Cd), and the adsorbent dosage (m) on the TB adsorption were studied. A Box–Behnken design (BBD) was applied to identify the effective factors on the removal efficiency (R%) of toluidine blue. The optimal conditions were as follows: m = 0.02 g, Cd = 100 mg L−1, and pH = 4.5. The equilibrium adsorption isotherms and kinetic models were also studied. Since the results of the Langmuir model fitted well to all the experimental data (R2 = 0.9972), the maximum monolayer adsorption of TB was 180.4 mg g−1. Furthermore, the pseudo-second-order model describes well the process. Iron terephthalate metal–organic framework (MOF-235) shows a great potential to remove TB from aqueous solution.

The enhanced removal of phosphate by structural defects and competitive fluoride adsorption on cerium-based adsorbent

Trivalent cerium (Ce(Ⅲ)) was demonstrated to have great potential for phosphate (P) removal. Besides the valence states, the relationship of nano-structure and adsorption capacity needs further study to explore more efficient adsorbents. Herein, a series of Ce(Ⅲ)-terephthalate (BDC) metal-organic framework (MOF) with linker deficiencies are fabricated to achieve excellent P capture. The defective density can be increased by decreasing the reaction time and the ratio of organic linkers/metal. TGA reveals Ce-BDC-48 synthesized with BDC:Ce ratio of 1:1 for 48 h possessed 2.5 missing linkers per inorganic node. And the P uptake of Ce-BDC-48 was 35% higher than that of Ce-BDC-72 without defects. The maximum adsorption capacity of Ce-BDC-48 was 278.8 mg/g for P and 128.0 mg/g for fluoride (F), respectively. The adsorption mechanism illustrates that both P and F mainly focus on the Ce(Ⅲ) active sites to achieve ligand exchange. The competing adsorption of P and F at the lower concentration of F (50 mg/L) indicates that the interference of F for P removal is insignificant on account of the selective preferential order of P. However, with the increment of F concentration (100 mg/L), amount of F with small sizes gathering around the adsorbent surface enlarge the steric hindrance to hinder the access of P, leading to the sharp decline of P uptake. This study not only provides promising candidate by the design of structural defects for the P removal in practical application but also give a deep analysis on the adsorption mechanism of P with competing F surrounded.

Assessing Crystallisation Kinetics of Zr Metal-Organic Frameworks through Turbidity Measurements to Inform Rapid Microwave-Assisted Synthesis.

Controlling the crystallisation of metal‐organic frameworks (MOFs), network solids of metal ions or clusters connected by organic ligands, is often hindered by the significant number of synthetic variables inherent to their synthesis. Coordination modulation, the addition of monotopic competing ligands to solvothermal syntheses, can allow tuning of physical properties (particle size, porosity, surface chemistry), enhance crystallinity, and select desired phases, by modifying the kinetics of self‐assembly, but its mechanism(s) are poorly understood. Herein, turbidity measurements were used to assess the effects of modulation on the solvothermal synthesis of the prototypical Zr terephthalate MOF UiO‐66 and the knowledge gained was applied to its rapid microwave synthesis. The studied experimental parameters—temperature, reagent concentration, reagent aging, metal precursor, water content, and modulator addition—all influence the time taken for onset of nucleation, and subsequently allow microwave synthesis of UiO‐66 in as little as one minute. The simple, low cost turbidity measurements align closely with previously reported in situ synchrotron X‐ray diffraction studies, proving their simplicity and utility for probing the nucleation of complex materials while offering significant insights to the synthetic chemist.

Multicomponent transport model-based scaling up of long-term adsorptive filtration of MOF incorporated mixed matrix hollow fiber membrane: Treatment of textile effluent

The present work describes the preparation and detailed characterization of porous chromium terephthalate metal–organic framework (MOF) impregnated polyacrylonitrile based hollow fiber membrane. The hollow fibers were characterized by their surface morphology, zeta potential, permeability, average pore diameter, molecular weight cut off (MWCO) and contact angle. Variation of MOF concentration upto 10 wt% resulted in 43% reduction in membrane permeability. The corresponding change in MWCO was from 140 kDa to 70 kDa. The addition of MOF made the membrane more hydrophilic and at 10 wt% MOF, the contact angle was reduced to 52° from 86°. The Fourier Transform Infrared Spectra (FTIR) of mixed matrix membrane (MMM) showed that there existed strong chemical interaction between MOF particles and polymer backbone, precluding the leaching of MOF from the membrane matrix over long term use. The MOF incorporated MMM exhibited tremendous adsorption capacity (197–260 mg/g for 10 wt% MOF doped fiber) towards reactive dyes commonly used in the textile industry. As the dye removal by MMM hollow fiber was based on the adsorption mechanism, the breakthrough behavior of the membrane was important to estimate the membrane life and onset of membrane regeneration. In the present work, a detailed two-dimensional transient transport model was developed for a multi-component real-life textile effluent from the first principles using the equation of continuity, momentum balance, species balance based on convective-diffusive-adsorptive solute transport in the hollow fiber. The model results were validated with the experimental data of a textile effluent having four reactive dyes. The multicomponent model was used for scaling up the actual hollow fiber based filtration system and the performance curve was generated relating the breakthrough volume, number and length of fibers.

Facile synthesis of a Cu-based metal-organic framework from plastic waste and its application as a sensor for acetone

A novel strategy is developed to solvothermally synthesize a Cu-based metal-organic framework (MOF), known as a copper terephthalate MOF, using terephthalic acid (TPA) as a linker which was extracted from small pieces of waste soft-drink bottles via alkaline hydrolysis. The extracted TPA as well as the obtained MOFs were all characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and Fourier-transform infrared spectroscopy. The Cu-MOF was applied to the detection of volatile organic compounds (VOCs) such as acetone (detection limit of ∼20 ppm) based on the photocatalytic principle under ultraviolet irradiation at room temperature. Cu-MOF procured from plastic waste is thus validated as a promising material for practical sensing applications.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework.

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is "blind" with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites. The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

Synthesis, Characterizations, and Adsorption Isotherms of CO2 on Chromium Terephthalate (MIL-101) Metal-organic Frameworks (Mofs)

Synthesis, Characterizations, and Adsorption Isotherms of CO2 on Chromium Terephthalate (MIL-101) Metal-organic Frameworks (Mofs)

Application of Chromium and Cobalt Terephthalate Metal Organic Frameworks as Catalysts for the Production of Biodiesel from Calophyllum inophyllum Oil in High Yield Under Mild Conditions

This paper describes the application of chromium(III) terephthalate (Cr-Tp) and cobalt(II) terephthalate (Co-Tp) metal organic frameworks, as heterogeneous acid catalysts to avoid the yield reduction caused by saponification during the process of biodiesel production using Calophyllum inophyllum oil. The catalysts were mainly characterized using spectroscopic (FTIR), microscopic (SEM, energy-dispersive X-ray spectroscopy) and X-ray diffractive techniques. The surface acidity and the thermal stability of the catalysts were determined using Hammett indicator and thermo-gravimetric methods, respectively. The catalysts were employed for the pre-esterification of free fatty acid content of the oil before subjecting the oil for the transesterification of its triglyceraldehyde content. The pre-esterification was performed through a couple of successive catalytic cycles under milder conditions [25°, 1 atm, and 2/1 MeOH/oil (w/w) ratio] than the conditions reported so far. The study revealed that the successful pre-esterification required these catalysts in very small amount (< 2.5% by oil weight) and occurred within very short time (2 h for the 1st cycle and 2–4 h for the 2nd cycle), reducing the acid value of C. inophyllum oil significantly (88%) from 56.91 to ~ 6.5 mg KOH g−1. The catalytic activity of these catalysts remained unchanged even after the 10th cycle of catalyst reuse. More importantly, the yield of biodiesel obtained from C. inophyllum oil in this way was significantly high (~ 93%) and free from saponification.

Heterogeneous Bimetallic Cu–Ni Nanoparticle-Supported Catalysts in the Selective Oxidation of Benzyl Alcohol to Benzaldehyde

Three bimetallic Cu–Ni nanoparticle-supported catalysts were synthesized by co-immobilization followed by H2 reduction. A chromium(III) terephthalate metal organic framework (MIL-101), titanium dioxide (TiO2), and carbon (C) with different properties (acidity and Brunauer–Emmett–Teller surface area) were selected as supports for studying the effect of the support nature on the catalytic activity and selectivity in the oxidation of benzyl alcohol. The physicochemical properties of the Cu–Ni-supported catalysts were characterized by XRD, NH3-TPD, nitrogen adsorption/desorption, TEM, EDS, XPS, and ICP-OES. Bimetallic Cu–Ni nanoparticles were highly dispersed on the support. The catalytic activities of CuNi/MIL-101, CuNi/TiO2, and CuNi/C were tested in the selective oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen under mild reaction conditions. The highest benzaldehyde yields were achieved with CuNi/TiO2, CuNi/MIL-101, and CuNi/C catalysts at 100 °C within 4 h under 5, 3, and 3 bar of O2, respectively. The bimetallic Cu–Ni-supported catalysts possessed two types of catalytic active sites: acid sites and bimetallic Cu–Ni nanoparticles. The CuNi/MIL-101 catalyst possessed a high number of acid sites and exhibited high yield during selective benzyl alcohol oxidation to benzaldehyde. Importantly, the catalysts exhibited a high functional group (electron-donating and electron-withdrawing groups) tolerance. Cu–Ni-supported catalysts with an Cu:Ni mole ratio of 1:1 exhibited the highest yield of 47% for the selective oxidation of benzyl alcohol to benzaldehyde. Reusability and leaching experiment results exhibited that CuNi/MIL-101 showed better stability than CuNi/TiO2 and CuNi/C catalysts due to the large porous cavities of MIL-101 support; these cavities can be used to trap bimetallic Cu–Ni nanoparticles and inhibit nanoparticle leaching.

A facile and regioselective synthesis of some new pyrimido[4,5-d][1,2,4]triazolo[1,5-a]pyrimidinediones catalyzed by Zn(BDC)-MOF under ultrasound irradiation

Zinc terephthalate metal-organic framework catalyzed one-pot, three-component reaction of 3-amino-1H-1,2,4-triazoles, aromatic aldehydes and barbituric acid to prepare some new pyrimido[4,5-d][1,2,4]triazolo[1,5-a]pyrimidinediones. The reactions conducted under ultrasonic irradiation and solvent-free conditions with good to excellent yields of products. The zinc terephthalate metal-organic framework catalyst could be recovered by a simple filtration and applied in consecutive runs with no significant decrease in the yield. The method was demonstrated to be a truly green process with economics and sustainability.

Synthesis of a chromium terephthalate metal organic framework and use as nanoporous adsorbent for removal of diazinon organophosphorus insecticide from aqueous media

MIL-101(Cr), as a chromium terephthalate metal organic framework (MOF), is synthesized hydrothermally and used for removal of diazinon from aqueous media. Different methods such as FT-IR, FE-SEM, TGA, XRD and BET analysis were applied for characterization of prepared MIL-101(Cr). The results revealed that MIL-101(Cr) has octahedral structure, 96% crystallinity, thermal stability up to 550 °C and about 2600 m2/g BET surface area with microporous structure. Adsorption experiments were designed by Design expert software and the effect of parameters such as pH (2–10), temperature (25–61 ), contact time (5–85 minutes) and adsorbent dosage (0.1–0.9 g/L) was investigated. Adsorption process was optimized by response surface methodology (RSM) and the optimum conditions of adsorption process was achieved in pH 6.5, temperature 25 °C, contact time 64 minutes and adsorbent dosage 0.74g/L which is lead to 96% removal of diazinon. In order to investigate the reusability and life time of MIL-101(Cr), the adsorbent is used in five successive cycles for adsorption of diazinon in fresh samples and good results are obtained. Langmuir and Freundlich isotherm models were deliberated by adsorption equilibrium data and Langmuir model show better conformity (R2 = 0.985) with the experimental results. Kinetic study was carried out using pseudo first order, pseudo second order and intraparticle diffusion kinetic models. Experimental data were better fitted to the pseudo second order with a correlation coefficient of 0.997 which signified that the experimental outcome of the adsorption of diazinon was a chemical adsorption.

Kinetics of Water Vapor Adsorption and Desorption in MIL-101 Metal–Organic Frameworks

The adsorption–desorption isotherms and relaxation curves of water in chromium terephthalate metal–organic frameworks (MOFs), MIL-101, were measured by the gravimetric method at 298 K and 1 atm. Th...