Particle Size Distribution and Characterization of High Siliceous and Microporous Materials

Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate （SAPO） microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer （PSA） and scanning electron microscope （SEM）. The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test （F-test） methods were performed for the significance of results by the analysis of variance （ANONA） and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett ＆ Teller （BET） volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.

Efficient separation of C_(4) olefins using tantalum pentafluor oxide anion-pillared hybrid microporous material

With the increasing demand for synthetic rubber,the purification of 1,3-butadiene(C_(4)H_(6))is of great industrial significance.Herein,the successful removal of n-butene(n-C_(4)H_(8))and iso-butene(iso-C_(4)H_(8))from 1,3-butadiene(C_(4)H_(6))was realized by synthesizing a novel TaOF_(5)^(2-) anion-pillared ultramicroporous material TaOFFIVE-3-Ni(also referred to as ZU-96,TaOFFIVE=TaOF_(5)^(2-),3=pyrazine).Single-component adsorption isotherms show that TaOFFIVE-3-Ni can achieve the exclusion of n-C_(4)H_(8) and iso-C_(4)H_(8) in the low pressure region(0–30 kPa),and uptake C_(4)H_(6) with a high capacity of 92.78 cm^(3)·cm^(-3)(298 K and 100 kPa).The uptake ratio of C_(4)H_(6)/iso-C_(4)H_(8) on TaOFFIVE-3-Ni was 20.83(298 K and 100 kPa),which was the highest among the state-of-the-art adsorbents reported so far.With the rotation of anion and pyrazine ring,the pore size changes continuously,which makes smaller-size C_(4)H_(6) enter the channel while larger-size n-C_(4)H_(8) and iso-C_(4)H_(8) are completely blocked.The excellent breakthrough performance of TaOFFIVE-3-Ni shows great potential in industrial separation of C4 olefins.The specific adsorption binding sites within ZU-96 was further revealed through the modeling calculation.

Preparation and Photocatalytic Application of the Microporous Decatungstate,Na_4W_(10)O_(32)/SiO

The photochemical behavior of polyoxometalates（POMs）have been studied extensivelyIn homogeneous solutions［1-3]．However，the major drawback to the practical applications ofthe homogeneous systems is the high water solubility of POMs，which impedes the readyrecovery and the reuse of the photocatalysts．Therefore，the preparation of insoluble POMs Isconsidered．More recently，we haveprepared insoluble POMs，i．e，Keggin－type microporousPOMs，H3PW12O40／SiO2 or H4SiW12O40／SiO2，and paratungstate A－containing pillaredcompound，Mg12Al6（OH）36（W7O24）·4H2O，for the purpose of photo－oxidation of aqueous

Organotemplate-free Hydrothermal Synthesis of SUZ-4 Zeolite: Influence of Synthesis Conditions

Various conditions were investigated in detail for the novel organic template-free static hydrothermal synthesis of SUZ-4 zeolite in the presence of seeds. The obtained samples were characterized by XRD （X-ray diffraction）, SEM （scanning electron microscope）, TG （thermal gravimetric analysis）, ICP （inductively coupling plasma） elemental analysis, nitrogen sorption isotherm and surface area. The results show that pure SUZ-4 zeolites with high crystallinity are obtained in a broad window of synthesis conditions： seed mass concentration 0.2%-2%, SIO2/A1203 molar ratio 21 25, KOH/SiO2 molar ratio 0.33 0.43, H20/SiO2 molar ratio 7.14-38.1, aging time 24 h, crystallization temperature 160℃, and crystallization time 6-10 d. Also, crystallinity and size of the rod-like SUZ-4 zeolite crystals are found to alter with the conditions.

A Structured Ultramicroporous Metal-Organic Framework for Carbon Dioxide Capture

Comprehensive Summary Carbon dioxide(CO_(2))capture is one of the most important aspects of reducing global warming.In terms of CO_(2)capture,metal-organic frameworks(MOFs)have several advantages.However,it isn't easy to shape MOFs while maintaining their performance.Herein,we describe the development of a pellet-shaped ultramicroporous MOF,Ni(3-ain)2(3-ain=3-aminoinoisonicotinic acid),that is capable of selectively adsorbing CO_(2).Polyvinyl butyral(PVB)is used as a binder during the production of Ni(3-ain)2 MOF pellets.The adequately shaped material can maintain its crystallinity and exhibit a high CO_(2)adsorption capacity(3.73 mmol·g^(-1))at ambient conditions,which is significantly greater than those obtained for N_(2)(0.63 mmol·g^(-1))and CO(0.90 mmol·g^(-1)).Consequently,this material displays high IAST selectivities for CO_(2)/N_(2)(26.3,15/85,V/V)and CO_(2)/CO(19.2,1/99,V/V).According to the theoretical calculations,Ni(3-ain)2 preferentially adsorbs CO_(2)molecules over N_(2)molecules and CO molecules.The results of experiments on dynamic breakthrough have demonstrated that Ni(3-ain)2 pellets are capable of effectively separating CO_(2)/N_(2)or CO_(2)/CO mixtures under conditions of dynamic flow.Furthermore,the structured MOF materials can be synthesized in one step at kilogram scale.This work provides an avenue for the shaping of MOFs for potential industrial applications in the future.

A novel synthesis process of ETS-4 titanosilicate using commercial anatase in the absence of fluoride ions

A novel synthesis process for ETS-4 titanosilicate using commercial anatase as the titanium source in the absence of fluoride ions was studied. Fluoride ions and traced ETS-4 seeds have important roles in forming ETS-4 structures. However, the method using ETS-4 seeds instead of fluoride ions to improve product purity and productivity is environment-friendly. ETS-4, ETS-4（NS）, and ETS-4（NaF） were respectively synthesized using traced ETS-4 seeds, without seeds, and with fluoride ions. The as-synthesized samples were identified by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. Adsorption isotherms and adsorption heats of nitrogen and methane on the prepared ETS-4 were also measured. The results showed that ETS-4 samples could be prepared using anatase in the absence of fluoride ions, with good purity, comparable physicochemical properties, and excellent adsorption properties.

Porous Silicon Carbide/Carbon Composite Microspherules for Methane Storage

Porous silicon carbide/carbon （SiC/C） microspherules were prepared by the controlled heating treatment of polymer and silica hybrid precursors over 1000℃ in Ar/H2 stream. The resultant SiC/C composite shows improved physical properties such as excellent mechanical strength, regular physical form, and high packing density. Such improvement overcomes the main inherent problems encountered when using activated carbons as absorbents without sacrificing porosity properties. N2 sorption analysis shows that the SiC/C composite has a BET surface area of 1793 m^2/g and a pore volume of 0.92 ml/g. Methane adsorption isotherm is determined by the conventional volumetric method at 25℃ and up to 7.0 MPa. On volumetric basis, the SiC/C composite microspherules show methane storage of 145 （V/V） at 3.5 MPa and 25℃. The combination of excellent physical properties and porosity properties in this SiC/C composite lends a great possibility to develop a competitive storage system for natural gas.

ZnO@Porous Media,Their PL and Laser Effect

Optoelectronic nanocomposites are a new class of materials, which exhibit very interesting and particular properties and attract a growing attention due to their potential applications in information storage and optoelectronic devices. Zinc oxide, ZnO, is one of the most interesting binary semiconductor （3.37 eV） with very important optical properties, which can be used in the fields such as short wavelength lasers, blue light emitting diodes, UV detectors, gas sensors, etc. This paper reviews the very recent progress in the prepa- ration of silica-based ZnO nanocomposites. After an introduction reviewing the theoretical background, the article will begin with a survey of the optical properties and the quantum size effect （QSE） of ZnO/SiO2 nanocomposites prepared by the inclusion of ZnO nanoclusters inside silica mesoporous materials. The second part will focus on one of the most interesting properties of ZnO/SiO2 nanocomposites, which is the random lasing effect after one- and two-photon excitation. The final part will deal with the introduction of ZnO nanoparticles inside microporous zeolites and the observation of QSE. For comparison, the photoluminescence （PL） and QSE properties of ZnS nanoparticles occluded in mesoporous media are also described. New potential applications will be discussed since short-wavelength devices are required by industry to design, for instance, new information storage supports and biolabelling devices.

Synthesis of Microporous Nitrogen-Rich Covalent-Organic Framework and Its Application in CO_(2) Capture

An imine-based nitrogen-rich covalent-organic framework(COF)was successfully synthesized using two tri-angular building units under solvothermal reaction condition.The gas adsorption properties of the obtained micro-porous nitrogen-rich COF were investigated.The results indicated that the activated COF material presented good up take capabilities of CO_(2) and CH_(4) at 61.2 and 43.4 cm^(3)·g^(−1)at 1 atm and 273 K,respectively,showing its applica-tion potential in selective gas capture and separation.

Synthesis of a Highly Crystalline Amide-Linked Covalent Organic Framework

The dilemma for the synthesis of covalent organic frameworks(COFs)is crystallinity and stability.Herein,we present the synthesis of a single-crystalline amide-linked COF,and demonstrate its excellent chemical as well as thermal stabilities.This study will inspire the synthesis of a wide spectrum of highly crystalline and stable COFs,promote their structure-property investigations and boost their applications in selective gas adsorption,storage and separation.

Solar thermal swing adsorption on porous carbon monoliths for high-performance CO_(2)capture

Utilizing solar energy for sorbent regeneration during the CO_(2)swing adsorption process could potentially reduce CO_(2)capture costs.This study describes a new technique—solar thermal swing adsorption(STSA)for CO_(2)capture based on application of intermittent illumination onto porous carbon monolith(PCM)sorbents during the CO_(2)capture process.This allows CO_(2)to be selectively adsorbed on the sorbents during the light-off periods and thereafter released during the light-on periods due to the solar thermal effect.The freestanding and mechanically strong PCMs have rich ultramicropores with narrow pore size distributions,displaying relatively high CO_(2)adsorption capacity and high CO_(2)/N_(2) selectivity.Given the high CO_(2)capture performance,high solar thermal conversion efficiency,and high thermal conductivity,the PCM sorbents could achieve high CO_(2)capture rate of up to 0.226 kg·kgcarbon^(-1)·h^(-1)from a gas mixture of 20 vol.%CO_(2)/80 vol.%N_(2) under STSA conditions with a light intensity of 1000 W·m^(-2).In addition,the combination of STSA with the conventional vacuum swing adsorption technique further increases the CO_(2)working capacity.

Microwave-assisted Ionothermal Synthesis and Characteriza- tion of Zeolitic Imidazolate Framework-8

The zeolitic imidazolate framework-8 （ZIF-8） was successfully synthesized using ionic liquids as struc- ture-directing agent under microwave irradiation. Ionic liquids are green solvents with low vapour pressure and good thermal stability. They are appropriate templates for microporous materials and ideal microwave absorbers. The microwave-assisted ionothermal synthesis applied in this paper was expected to be a promising method for the preparation of microporous materials. Results showed that the as-synthesized samples （300---500 nm in diameter） could be synthesized in a short time （60 min） and possessed regular morphology, stable structure and high thermal stability （up to 720 ~C in argon atmosphere）. Nitrogen adsorption-desorption test illustrated that samples produced by microwave heating had a higher surface area. Carbon dioxide adsorption test indicated that the samples synthe- sized by microwave heating had better carbon dioxide adsorption ability than those by conventional heating.

Three-Dimensional sp^(2) Carbon-Linked Covalent Organic Frameworks as a Drug Carrier Combined with Fluorescence Imaging

Three-dimensional(3D)covalent organic frameworks(COFs)are crystalline porous polymers with potential in numerous high-tech applications,but the linkages involved in their synthesis are still rather limited.Herein,we report novel 3D sp^(2) carbon-linked COFs fabricated by the formation reaction of C=C bonds and their application in fluorescence imaging.These new COFs,namely JUC-580 and JUC-581,show high stability and excellent light-emitting properties in solid state and dispersed in various solvents.Furthermore,we investigate the potential application of JUC-581 as a drug carrier combined with fluorescence imaging.These results indicate that 3D sp^(2) carbon-linked COFs are not only potential drug-loaded and sustained release materials but also promising cell fluorescent stains.This study thus expands the structural categories of 3D COFs based on different linkages,and promotes their prospective applications for biomedicine and fluorescent materials.

Solvent-Controlled Construction of Molecular Chains and Bowls/Sieves from a Bent Dipyridyl Ligand

Solvothermal reactions of 3,6-di(pyridin-4-yl)-9H-carbazole(dpc)with Cu(ll)yielded crystals of two new coordination complexes,namely[Cu(CH_(3)COO)_(2)(dpc)(H_(2)O)_(2)]n-xGuest(1)and[Cu_(13)(HCOO)_(16)(dpc)16(H_(2)O)6](HCOO)10-Guest(2),in which CH_(3)COO_and HCOO-were generated from the hydrolysis of the solvents A/zAZ-dimethylacetamide(DMA)and A/zA/-dimethylformamide(DMF),respectively.Single-crystal X-ray diffraction showed that 1 possesses simple wavy coordination chains,while 2 possesses large molecular bowls/sieves with outer and inner effective sizes of 30.2 × 30.2 × 25.5 A^(3) and 15.0 × 15.0 × 18.6 A^(3),respectively,which consists of 4 linear Cu_(3)(HCOO)_(4)(H_(2)O)clusters and 12 dpc ligands as the square-shaped wall and a claw-like Cu(dpc)_(4) fragment as the bottle.Guest-free 2 can adsorb considerable amounts of CO_(2)/H_(2)O and CH_(3)OH but completely exclude C2H4 and C3H6z which shows a potential application for olefin drying.

Microstructure Manipulation of Covalent Organic Frameworks(COFs)-based Membrane for Efficient Separations

Covalent organic framework(COF) membranes have exhibited great potential to become the next-generation membranes for efficient separations due to the diverse structures, ordered framework pores, tunable functionality and excellent stability. This review presents the microstructure manipulation strategies for separation performance enhancement of COF membranes in recent years. Based on the three mechanisms of molecular sieving, surface diffusion, and facilitated transport, the structural modulation methods to enhance the selectivity of COF membranes are analyzed in detail. Next, strategies of realizing ultrashort mass transfer pathways and ultralow mass transfer resistance for the permeability enhancement are elaborated. Furthermore, the framework stability in COFs, interlayer stability between COF nanosheets and interfacial stability between COF layer and substrate are discussed. Finally, we discuss the existing challenges and perspectives on the future development of COF membranes, targeting at identifying the most promising strategies and directions for the engineering of COF membranes.