Crystalline Microporous Materials Research Articles

Improvement of cooling performance of water adsorption chiller by using aluminophophate adsorbent

We synthesized an aluminophosphate (AlPO4)-based adsorbent that shows great cooling performance when used in a water adsorption chiller as an adsorbent. This adsorbent is crystalline microporous (CHA-type structure) material, which is composed of aluminum, phosphine, and oxygen atoms. It shows high water adsorption capacity (0.3 gH2O gads−1) at 308 K under 12 Torr of water vapor pressure (typical adsorption conditions of the adsorption chiller), and almost zero adsorption capacity at 348 K under 42 Torr (typical desorption conditions). This adsorbent shows much larger working capacity between the adsorption and desorption steps than silico-aluminophosphate (SAPO4) adsorbent which has same physico-chemical properties as the AlPO4, except for the absence of silicon species in framework. The commercial water adsorbent, FAM-Z02 is known to have the same structure as this SAPO4. We confirmed that AlPO4 can be easily synthesized in a large scale with a high hydrothermal stability, and easily pelletized to 0.6–1 mm sphere-shaped particles. The present AlPO4 adsorbent was tested in lab-made water adsorption chiller with 5 kW scale, and it shows 523 W kg−1 of specific cooling power (SCP). This experimental value was in good agreement with SCP (513 W kg−1) derived from simulation. The SCP of the AlPO4 adsorbent is 28% larger than that of the SAPO4 adsorbent calculated from simulation.

Ultrafast Encapsulation of Metal Nanoclusters into MFI Zeolite in the Course of Its Crystallization: Catalytic Application for Propane Dehydrogenation.

Encapsulating metal nanoclusters into zeolites combines the superior catalytic activity of the nanoclusters with high stability and unique shape selectivity of the crystalline microporous materials. The preparation of such bifunctional catalysts, however, is often restricted by the mismatching in time scale between the fast formation of nanoclusters and the slow crystallization of zeolites. We herein demonstrate a novel strategy to overcome the mismatching issue, in which the crystallization of zeolites is expedited so as to synchronize it with the rapid formation of nanoclusters. The concept was demonstrated by confining Pt and Sn nanoclusters into a ZSM-5 (MFI) zeolite in the course of its crystallization, leading to an ultrafast, in situ encapsulation within just 5 min. The Pt/Sn-ZSM-5 exhibited exceptional activity and selectivity with stability in the dehydrogenation of propane to propene. This method of ultrafast encapsulation opens up a new avenue for designing and synthesizing composite zeolitic materials with structural and compositional complexity.

Ultrafast Encapsulation of Metal Nanoclusters into MFI Zeolite in the Course of Its Crystallization: Catalytic Application for Propane Dehydrogenation

AbstractEncapsulating metal nanoclusters into zeolites combines the superior catalytic activity of the nanoclusters with high stability and unique shape selectivity of the crystalline microporous materials. The preparation of such bifunctional catalysts, however, is often restricted by the mismatching in time scale between the fast formation of nanoclusters and the slow crystallization of zeolites. We herein demonstrate a novel strategy to overcome the mismatching issue, in which the crystallization of zeolites is expedited so as to synchronize it with the rapid formation of nanoclusters. The concept was demonstrated by confining Pt and Sn nanoclusters into a ZSM‐5 (MFI) zeolite in the course of its crystallization, leading to an ultrafast, in situ encapsulation within just 5 min. The Pt/Sn‐ZSM‐5 exhibited exceptional activity and selectivity with stability in the dehydrogenation of propane to propene. This method of ultrafast encapsulation opens up a new avenue for designing and synthesizing composite zeolitic materials with structural and compositional complexity.

Zeotype SAPO‐34 Synthesized by Combination of Templates for the Gasification of Biomass

AbstractSAPO‐34 is a crystalline microporous material, the characteristics of which are greatly influenced by synthetic parameters, especially the silica precursors and templates. In this study, the combination of templates and silica sources was optimized to obtain SAPO‐34 phases in the purest form. The physicochemical properties of the thus‐synthesized catalysts were characterized, and the Si environment in the SAPO‐34 framework was analyzed. The catalytic performance in biomass gasification was investigated in a fixed‐bed flow reactor. SAPO‐34 synthesized with triethylamine/morpholine/tetraethylammonium hydroxide templates exhibited the highest total acidity, the smallest particle size, and high surface area, and produced a large amount of light hydrocarbons in biomass gasification.

Formation Pathway of AEI Zeolites as a Basis for a Streamlined Synthesis

Zeolites are commercially used crystalline microporous materials. Understanding their crystallization mechanism and corresponding synthesis development is still of scientific and technological sign...

Machine Learning Applied to Zeolite Synthesis: The Missing Link for Realizing High-Throughput Discovery.

Zeolites are microporous crystalline materials with well-defined cavities and pores, which can be prepared under different pore topologies and chemical compositions. Their preparation is typically defined by multiple interconnected variables (e.g., reagent sources, molar ratios, aging treatments, reaction time and temperature, among others), but unfortunately their distinctive influence, particularly on the nucleation and crystallization processes, is still far from being understood. Thus, the discovery and/or optimization of specific zeolites is closely related to the exploration of the parametric space through trial-and-error methods, generally by studying the influence of each parameter individually. In the past decade, machine learning (ML) methods have rapidly evolved to address complex problems involving highly nonlinear or massively combinatorial processes that conventional approaches cannot solve. Considering the vast and interconnected multiparametric space in zeolite synthesis, coupled with our poor understanding of the mechanisms involved in their nucleation and crystallization, the use of ML is especially timely for improving zeolite synthesis. Indeed, the complex space of zeolite synthesis requires drawing inferences from incomplete and imperfect information, for which ML methods are very well-suited to replace the intuition-based approaches traditionally used to guide experimentation. In this Account, we contend that both existing and new ML approaches can provide the "missing link" needed to complete the traditional zeolite synthesis workflow used in our quest to rationalize zeolite synthesis. Within this context, we have made important efforts on developing ML tools in different critical areas, such as (1) data-mining tools to process the large amount of data generated using high-throughput platforms; (2) novel complex algorithms to predict the formation of energetically stable hypothetical zeolites and guide the synthesis of new zeolite structures; (3) new "ab initio" organic structure directing agent predictions to direct the synthesis of hypothetical or known zeolites; (4) an automated tool for nonsupervised data extraction and classification from published research articles. ML has already revolutionized many areas in materials science by enhancing our ability to map intricate behavior to process variables, especially in the absence of well-understood mechanisms. Undoubtedly, ML is a burgeoning field with many future opportunities for further breakthroughs to advance the design of molecular sieves. For this reason, this Account includes an outlook of future research directions based on current challenges and opportunities. We envision this Account will become a hallmark reference for both well-established and new researchers in the field of zeolite synthesis.

Unraveling the Enhanced Cycling Performance of Lithium–Oxygen Batteries Based on Metal Organic Frameworks

Owing to their five times higher energy density (~3500 Wh/kg) than that of lithium-ion batteries, lithium–oxygen (Li–O2 or Li­–air) batteries have been considered as one of the most promising next-generation energy storage devices.1 However, Li–O2 batteries still suffer from several challenges that hinder their practical applications, including low energy efficiency and short cycle life. It has been well-documented that such challenges are mainly caused by the parasitic reactions between cell components (e.g., cathodes and electrolytes) and aggressively reactive oxygen species (e.g., singlet O2 and superoxide radicals), which result in the repaid passivation and failure of Li–O2 batteries.2,3 Therefore, the cycling performance of Li–O2 batteries can be significantly improved by suppressing those parasitic reactions. Metal–organic frameworks (MOFs), an emerging type of crystalline microporous materials, have been widely studied as cathodes, separators, and electrolytes for high-energy Li batteries due to their large surface area, high porosity, and chemically unsaturated metal sites.4 For example, our group recently reported a MOF/CNT cathode for Li–O2 batteries with enhanced cycling performance via the formation and decomposition of less-reactive LiOH compared to Li2O2.5 Besides, MOF-modified separators have also been reported as molecular/ionic sieves to mitigate the shuttling effect of polysulfides in lithium–sulfur batteries and redox mediators in Li–O2 batteries.6,7 Herein, we present our mechanistic study on the enhanced performance of MOF-based Li–O2 batteries. Operando characterization techniques including Raman and mass spectrometry and ex-situ quantitative techniques including NMR and titration were carried out to comprehensively understand the reaction mechanism and the reversibility of Li­–O2 chemistry. The enhanced battery performance and reaction mechanism will be discussed in this presentation. Reference (1) Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J. M. Li–O2 and Li–S batteries with high energy storage. Nat. Mater. 2012, 11, 19-29. (2) Mahne, N.; Fontaine, O.; Thotiyl, M. O.; Wilkening, M.; Freunberger, S. A. Mechanism and Performance of Lithium–Oxygen Batteries–a Perspective. Chem. Sci. 2017, 8, 6716-6729. (3) Aurbach, D.; McCloskey, B. D.; Nazar, L. F.; Bruce, P. G. Advances in Understanding Mechanisms Underpinning Lithium–Air Batteries. Nat. Energy 2016, 1, 16128. (4) Zhang, X.; Dong, P.; Song, M.-K. Metal–Organic Frameworks for High-Energy Lithium Batteries with Enhanced Safety: Recent Progress and Future Perspectives. Batteries & Supercaps 2019, https://doi.org/10.1002/batt.201900012. (5) Zhang, X.; Dong, P.; Lee, J.-I.; Gray, J. T.; Cha, Y.-H.; Ha, S.; Song, M.-K. Enhanced Cycling Performance of Rechargeable Li–O2 Batteries via LiOH Formation and Decomposition Using High-Performance MOF-74@CNTs Hybrid Catalysts. Energy Storage Mater. 2019, 17, 167-177. (6) Bai, S.; Liu, X.; Zhu, K.; Wu, S.; Zhou, H. Metal–organic framework-based separator for lithium–sulfur batteries. Nat. Energy 2016, 1, 16094. (7) Qiao, Y.; He, Y.; Wu, S.; Jiang, K.; Li, X.; Guo, S.; He, P.; Zhou, H. MOF-Based Separator in an Li–O2 Battery: An Effective Strategy to Restrain the Shuttling of Dual Redox Mediators. ACS Energy Lett. 2018, 3, 463-468.

Wetting Properties and Thin-Film Quality in the Wet Deposition of Zeolites.

Zeolites are microporous crystalline materials widely used in catalysis and adsorption applications. The fabrication of zeolite thin films and membranes has also opened up the possibility of using zeolites in electronic devices and membrane separations. The existing approach to growing zeolite films involves exposing the substrate to a high-pH environment; however, this process is applicable to only specific types of substrates. Our group has developed the direct wet deposition of zeolites via ultrasonic nozzle spray deposition to address this issue; however, the relationship between wetting properties and thin-film quality has yet to be investigated. In this study, we prepared zeolite CHA (Si:Al:P = 3:10:20) suspensions using different solvents and surfactants in various concentrations. We then examined the relationships among the composition of the cast solution, their wetting behavior on the glass substrate, and the uniformity of the resulting thin films. We found that using ethanol as a solvent with zeolite crystals in low concentrations with added surfactant yielded zeolite films of high quality. We were also able to produce low-haze zeolite coatings on glass. The zeolite coatings with high hydrophilicity and adsorption capacity presented excellent antifogging capability.

Thermodynamically Consistent Methodology for Estimation of Diffusivities of Mixtures of Guest Molecules in Microporous Materials.

The Maxwell–Stefan (M–S) formulation, that is grounded in the theory of irreversible thermodynamics, is widely used for describing mixture diffusion in microporous crystalline materials such as zeolites and metal–organic frameworks (MOFs). Binary mixture diffusion is characterized by a set of three M–S diffusivities: Đ1, Đ2, and Đ12. The M–S diffusivities Đ1 and Đ2 characterize interactions of guest molecules with pore walls. The exchange coefficient Đ12 quantifies correlation effects that result in slowing-down of the more mobile species due to correlated molecular jumps with tardier partners. The primary objective of this article is to develop a methodology for estimating Đ1, Đ2, and Đ12 using input data for the constituent unary systems. The dependence of the unary diffusivities Đ1 and Đ2 on the pore occupancy, θ, is quantified using the quasi-chemical theory that accounts for repulsive, or attractive, forces experienced by a guest molecule with the nearest neighbors. For binary mixtures, the same occupancy dependence of Đ1 and Đ2 is assumed to hold; in this case, the occupancy, θ, is calculated using the ideal adsorbed solution theory. The exchange coefficient Đ12 is estimated from the data on unary self-diffusivities. The developed estimation methodology is validated using a large data set of M–S diffusivities determined from molecular dynamics simulations for a wide variety of binary mixtures (H2/CO2, Ne/CO2, CH4/CO2, CO2/N2, H2/CH4, H2/Ar, CH4/Ar, Ne/Ar, CH4/C2H6, CH4/C3H8, and C2H6/C3H8) in zeolites (MFI, BEA, ISV, FAU, NaY, NaX, LTA, CHA, and DDR) and MOFs (IRMOF-1, CuBTC, and MgMOF-74).

Solvent-Free Synthesis of CuO/HKUST-1 Composite and Its Photocatalytic Application.

A metal-organic framework (MOF) is one kind of crystalline microporous material and is increasingly used as a host of catalytically active guests. Nanostructured materials supported on MOFs have presented enhanced catalytic activity and stability. Templates or several steps are essential to the synthesis of MOF composites. Simple and effective MOF synthesis methods are still challenging. Nanosized copper oxide particles in MOF composites, described as nanosized CuO@HKUST-1, were prepared by a facile solvent-free reaction. These series of CuO@HKUST-1 composites exhibited excellent photocatalytic activity for production of hydrogen and methylene blue (MB) degradation under visible light. This synthesis method provides an effective way to fabricate MOF-related nanocomposite catalysts.

Rediscovery of the Importance of Inorganic Synthesis Parameters in the Search for New Zeolites.

Zeolites and related crystalline microporous materials with cavities and channels of molecular dimensions are of major importance for applications ranging from ion-exchange to adsorption and to catalysis. Because their unique shape-selective properties are closely related to the size, shape, and dimensionality of the intracrystalline channels and cavities, much interest has been devoted to the discovery of novel zeolitic materials over the last several decades. As a result, a dramatic expansion in the structural domain of crystalline microporous materials, as well as in their compositional range, has been achieved. This is largely due to the development of innovative synthetic strategies, for example, organic structure-directing agent (OSDA) design, introduction of heteroatoms like Ge in OSDA-mediated zeolite synthesis, topotactic transformation of two-dimensional layered zeolite precursors, assembly-disassembly-organization-reassembly method, etc. However, although many of these methodologies are quite successful in finding unprecedented zeolite structures, the resulting materials tend to be (hydro)thermally unstable and are often commercially impractical from a manufacturing perspective because of the high cost of the OSDA and/or heteroatom employed. Therefore, we focused on inorganic synthesis parameters as the key phase selectivity factor that has received relatively little attention in the search for new industrially relevant zeolites. This Account describes our recent efforts to find previously undiscovered aluminosilicate zeolites by boosting the roles of inorganic structure-directing agents (ISDAs) in the presence of OSDAs. They include the multiple inorganic cation and excess fluoride approaches, which aim to promote a synergistic cooperation between ISDAs and/or OSDAs and thus to hold a rational design concept, although the latter is not friendly to the practical zeolite manufacturing process due to the toxicity of fluoride. Using these two approaches, we were able to synthesize not only the second generation (PST-29) and four higher generations (PST-20 (RHO-G5), PST-25 (RHO-G6), PST-26 (RHO-G7), and PST-28 (RHO-G8)) of the RHO family of embedded isoreticular zeolites but also three other novel zeolite structures (EU-12, PST-21, and PST-22). We also explored the synthesis of a number of heteroatom-containing aluminophosphate (AlPO4) molecular sieves with different framework structures and unusually high framework charge density through the cooperative structure direction of alkali metal and small OSDA cations or under wholly inorganic conditions. Although we need to clarify the nature and extent of interactions between the inorganic cations and framework components in synthesis mixtures, we believe that our synthetic concepts, shedding new light on the importance of inorganic synthesis parameters, will open a door for achieving many other novel zeolite structures and compositions.

Hydroisomerization of n-hexadecane over Hβ molecular sieve loading palladium bifunctional catalyst: effect of SiO2/Al2O3 molar ratios

Hβ molecular sieves with different SiO2/Al2O3 ratios (Hβ(x))and Hβ(x) loading Pd(0.5 wt%) bifunctional catalysts(Pd/Hβ(x)) were prepared by hydrothermal synthesis and incipient wetness impregnation, respectively. The structure, morphology, pore and acid properties of Hβ(x) and Pd dispersion of Pd/Hβ (x) were characterized using XRD, SEM, N2 physical adsorption, NH3-TPD and H2 chemical absorption. Hβ (x) samples were highly crystalline microporous materials. With the increase of SiO2/Al2O3 ratios, BET surface area, micro-pore surface area and volume of Hβ (x) gradually decreased, and the external surface area and mesoporous volume gradually increased, and the number and acid strength of weak acid sites for Hβ(x) and Pd dispersion for Pd/Hβ(x) decreased. It was known from hydroisomerization perforamce of n-C16H34 that Pd/Hβ(40) catalysts showed the highest conversion of of 96.9% at 230°C. The select ivity of iso-C16H34 reached the highest value at the n-C16H34 conversion of 45~50%. Pd/Hβ(40) cata lysts exhib ited the highest iso-C16H34 selectivity of 84.4%, much more multi-branched iso-C16H34 and C4+C5 cracking components. The decrease of SiO2/Al2O3 molar ratios can increase the number of acid sites and dispersion of Pd/Hβ(x) bifunctional catalysts, thus not only aggravating the secondary heterogeneous reaction, but also accelerating the serious secondary cracking reaction.

Phonons in deformable microporous crystalline solids

Abstract Phonons are quantum elastic excitations of crystalline solids. Classically, they correspond to the collective vibrations of atoms in ordered periodic structures. They determine the thermodynamic properties of solids and their stability in the case of structural transformations. Here we review for the first time the existing examples of the phonon analysis of adsorption-induced transformations occurring in microporous crystalline materials. We discuss the role of phonons in determining the mechanism of the deformations. We point out that phonon-based methodology may be used as a predictive tool in characterization of flexible microporous structures; therefore, relevant numerical tools must be developed.

Effect of Synthesis Temperature Formation of the Structure and Properties of Silicoaluminophosphate with the AEI Structure

Changes in the phase, morphological, and textural properties of silicoaluminophosphates with the AEI structure during crystallization at 150, 170, and 190°С are studied. Using a combination of physicochemical methods, evolution of the solid phase extracted at different steps of synthesis is shown. It is established that at 150°С the microporous phase containing silicon in tetrahedral positions of the framework appears already at the initial stages of crystallization and further nanostructuring of the solid phase is associated with the incorporation of silicon via the SM3 mechanism. At 170°С, crystallization proceeds through formation of the aluminophosphate and aluminosilicate mixed mesoporous composite. The transformation of mixed composite into the microporous crystalline material is accompanied by the incorporation of [SiO4] isolated tetrahedra into the forming crystalline framework according to the SM2 mechanism; this provides a strong acidity of the material. The intermediate mesoporous semiproduct extracted at the initial stages of synthesis at 190°С is a mixture of disordered aluminophosphate and coarse mesoporous agglomerates; their transformation into silicoaluminophosphate with the AEI structure occurs only upon silica transfer to the liquid phase, and the incorporation of silicon into the AEI crystalline framework proceeds via the SM3 mechanism with the subsequent formation of silicon islands.

Preparation of Siloxane-Based Microporous Crystals from Hydrogen-Bonded Molecular Crystals of Cage Siloxanes.

Controlled assembly of siloxane-based building blocks provides a rational approach toward designed architectures of silica-based porous materials. Here, a non-hydrothermal method to prepare microporous crystals from cage-type oligosiloxanes is reported. The crystals formation occurs through an ordered assembly assisted by hydrogen bonds and subsequent intermolecular connection by silylation. Cage siloxanes with a double-four ring (D4R) structure were modified with dimethylsilanol groups. Intermolecular hydrogen bonding of the dimethylsilanol groups led to the formation of a pillared-layer structure consisting of D4R units. A new crystalline microporous material retaining the original ordered arrangement was realized by bridging adjacent cages within the crystals by direct silylation of the silanol groups with trichlorosilane. The use of this silylating agent created microporous crystals containing Si-H groups, proving the advantages of the proposed concept.

Multi-dimensional Crystal Structuring of Complex Metal Oxide Catalysts of Group V and VI Elements by Unit-Assembling

Four new porous crystalline complex metal oxide families based on group V and VI elements, all of which are synthesized through unit-assembling, are introduced along with crystal structure formation mechanism. Polyoxometalates (POMs) are utilized as building units and assembled for constructing microporous complex metal oxides. Assembling of MoVO-POMs having pentagonal units of [Mo6O21] with {VO} linkers under hydrothermal conditions forms microporous orthorhombic (NH4)4[Mo30V4O106] {VO}6 oxide and trigonal (NH4)3[Mo19.5V1.5O69] {VO}6 oxide. Assembling of e-Keggin Mo-POMs with bismuth ions as a linker under a hydrothermal condition produces a cubic (NH4)4[Mo9.4V3.6O40] {Bi}2 crystal with cages and channels with the diameter sizes of 0.77 and 0.34 nm, respectively. One dimensional anionic tungstosellenate molecular wire building block, [SeW6O21]2−n, is first formed by linear connection of hexagonal tungstosellenate POM units [SeW6O27] and then linked with the CoII ion to form a crystalline microporous materials, (NH4)0.4 [SeW6O21] {Co(OH)}1.3. [W4O16] building blocks are orderly connected with {VO} linkers to form a microporous framework (K1.5(NH4)0.2H0.3[W4O16]{VO}3) with a pore diameter of 0.43 nm which is fully opened and is accessible to small molecules. These new porous crystalline complex metal oxides showed high catalytic performance for alkane oxidation, aldehyde oxidation, alcohol oxidation, H2O2 oxidation, NH3-SCR, and so on.

Breaking Structural Energy Constraints: Hydrothermal Crystallization of High-Silica Germanosilicates by a Building-Unit Self-Growth Approach.

Zeolites, a class of crystalline microporous materials, have a wide range of practical applications, in particular serving as key catalysts in petrochemical and fine-chemical processes. Millions of zeolite topologies are theoretically possible. However, to date, only 235 frameworks with various tetrahedral element compositions have been discovered in nature or artificially synthesized, among which approximately 50 topologies are available in pure-silica forms. Germanosilicates are becoming an important zeolite family, with a rapidly increasing number of topological structures having unusual double four-membered ring (D4R) building units and large-pore or extra-large-pore systems. The synthesis of their high-silica analogues with higher (hydro)thermal stability remains a great challenge, because the formation of siliceous D4R units is kinetically and thermodynamically unfavorable in hydrothermal systems. Herein, it is demonstrated that such D4R-containing high-silica zeolites with unexpected crystalline topologies (ECNU-24-RC and IM-20-RC) are readily constructed by a versatile route. This strategy provides new opportunities for the synthesis of high-silica zeolite catalysts that are hardly obtainable by conventional hydrothermal synthesis and may also facilitate a breakthrough in increasing the number and types of zeolite materials with practical applications.

Understanding Commonalities and Interplay Between Organotemplate‐Free Zeolite Synthesis, Hierarchical Structure Creation, and Interzeolite Transformation

AbstractZeolites are crystalline microporous materials that have been widely used in many applications related to industrial catalysis, ion‐exchange, and adsorption. In recent years, there has been a growing emphasis on the development of green chemistry toward more sustainable zeolite synthesis routes. Considerable efforts have been devoted to identifying alternative approaches in order to reduce the negative impacts of organic templates. This review will focus on the significant progress achieved during the past decade on the development of novel organotemplate‐free strategies through three distinctive topics, i. e. zeolite synthesis, hierarchical zeolite synthesis, and interzeolite transformation. The progress of each topic will be documented, followed by a summary of the intriguing commonalities and interplay among these approaches. The insights into the mechanism and interplay leading to different zeolite materials will enable us to understand the requirements for designing novel zeolite catalysts and catalyst supports in an organotemplate‐free environment that are likely to further enhance the industrial impact of these materials in the future. We conclude this article with a perspective and outlook focusing on current trends and future directions in this area.

Amine-Functionalized Metal–Organic Framework as a New Sorbent for Vortex-Assisted Dispersive Micro-Solid Phase Extraction of Phenol Residues in Water Samples Prior to HPLC Analysis: Experimental and Computational Studies

Metal–organic frameworks (MOFs) are a new class of hybrid inorganic–organic microporous crystalline materials, which possess unique properties such as high surface area, tunable pore size, and good thermal stability. These unique characteristics make MOFs interesting targets for sample pretreatment. In this work, MIL-53 material based on aluminum and containing amine functional groups (NH2-MIL-53(Al)) was synthesized and applied as an efficient sorbent for development of vortex-assisted dispersive micro-solid phase extraction for eight United States Environmental Protection Agency’s priority phenols from aqueous samples prior to analysis by high-performance liquid chromatography with photodiode-array detection. A simple extraction process was designed. The parameters affecting the extraction efficiency, such as amount of sorbent, extraction time, type of desorption solvent and its volume were investigated. The good linearity in the concentration range of 0.0015–10.0000 μg mL−1 with the coefficients of determination of greater than 0.9929, low limits of detection (0.0004–0.0133 μg mL−1) and relative standard deviations of lower than 10% were obtained. The proposed method has been successfully applied to the determination of phenol compounds in different water sample matrices including treated water, waste water, river water, sea water, lake water, drinking water and tap water. In addition, computational simulation was performed to predict the adsorption ability of NH2-MIL-53(Al) towards the studied phenolic compounds. The computational results were in agreement with the experimental studies and it has been proved that NH2-MIL-53(Al) is promising for enrichment of phenolic pollutants.

Esterification process catalyzed by ZSM-5 zeolite synthesized via modified hydrothermal method

A modified hydrothermal method for ZSM-5 synthesis was described. The crystals gave a typical pattern (2? at around 22.5°, 24.0° and 29.8° corresponding to the major peaks of (501, 303 and 503 crystal surfaces)), which indicated that the subnanocrystals could have the primary structure of MFI-type zeolites. the FT-IR spectra of subnanocrystals which have the primary structure of MFI zeolites. Oleic acid methyl ester (OAME) was prepared via a rapid derivatization procedure. the acidic strength is determined by the zeolite crystal structure and the higher esterification rate of ZSM-5 can be attributed to its stronger acidity compared to H2SO4, especially after 50?min of reaction. ZSM-5 can be an excellent substitute to sulfuric acid which caused corrosion and equipments damage.•Zeolites are popular industrial catalysts comprised of crystalline microporous materials.•A modified hydrothermal method was used for ZSM-5 synthesis.•Synthesized ZSM-5 has a typical subnanocrystals structure corresponds to MFI- type Zeolite.•ZSM-5 can be an excellent substitute to sulfuric acid for the catalysis of esterification reactions.