Inorganic Zeolites Research Articles

新機能材料開発と構造科学 １．構造と機能 新しい結晶性多孔質物質「金属錯体ポーラス材料」の構造と機能

Coordination Polymers (CPs) are opening up a new field in porous materials. A large number of CPs have been so far synthesized and characterized because of their versatile applicability to gas storage, molecular sieves, size- or shape-selective catalysis, and ion exchange. Moreover, CPs, in spite of their crystalline form, are suitable for creating flexible and dynamic porous frameworks, which are hardly realized by inorganic zeolites and carbon materials. We described here the several unique structures and functions of CPs.

The Surface of Inorganic Oxides or Zeolites as a Nonconventional Reaction Medium for the Selective Synthesis of Metal Carbonyl Complexes and Clusters

AbstractFor Abstract see ChemInform Abstract in Full Text.

Phase-mineral and chemical composition of coal fly ashes as a basis for their multicomponent utilization. 2. Characterization of ceramic cenosphere and salt concentrates

The phase-mineral and chemical composition of ceramic cenosphere (CCCs) and water-soluble salt (WSCs) concentrates recovered from five fly ashes (FAs) produced in four large Spanish thermo-electric power stations was characterized. The CCCs and WSCs were isolated by sink-float separation in water and evaporation of the water-soluble solutions leached from FAs, respectively. The CCCs recovered are in the range 0.2–1.1% and their phase-mineral composition (in decreasing order of significance) commonly includes aluminosilicate glass, calcite, mullite, quartz, cristobalite, char, plagioclase, K-feldspar, dolomite, gypsum, and Fe oxides. The CCCs are enriched in Al, Ca, Ce, Co, Rb, Se and Sr in comparison with the FAs. The WSCs isolated are in the range 0.2–0.6% and their phase-mineral composition (in decreasing order of significance) normally includes gypsum, calcite, bassanite, inorganic amorphous matter, anhydrite, alunite, halite, opal, zeolite, dolomite, ankerite and jarosite. The WSCs are abundant in S and Ca, to a lesser extent in Al, Si, Na, K, Mg, Cl, Fe, P and Ti, and contain trace elements such as Cs, Li, Mn, Ni, Sn and Sr with ppm level, and As, Ba, Cr, Cu, Ge, Mo, Pb, Rb, Sb, Se, V, Zn and Zr with ppb level. Most of the elements studied are depleted and only Ca, Cl, K, Na and S are enriched in WSCs in comparison with the FAs. Significant proportions of Ca, Cl, Na and S (2–29%), and to a lesser extent of Al, Cs, K, Mg, P, Si, Sn and Ti (0.1–1%) were leached from the initial elemental contents in FAs. Some genetic features, properties, possible environmental concern and potential utilization directions related to the CCCs and WSCs are also discussed.

The surface of inorganic oxides or zeolites as a nonconventional reaction medium for the selective synthesis of metal carbonyl complexes and clusters.

The surface of inorganic oxides or zeolites as a nonconventional reaction medium for the selective synthesis of metal carbonyl complexes and clusters.

Química organometálica de superfície aplicada à preparação de catalisadores heterogêneos bem definidos

The study of the reactions of organometallic complexes with the surfaces of inorganic oxides, zeolites and metals constitutes the basis of Surface Organometallic Chemistry (SOMC). The basic rules of organometallic chemistry are often valid when applied to surfaces and well-defined surface organometallic complexes can be obtained. These complexes can be used as heterogeneous catalysts or, by controlled reactions, can be transformed in other species useful for a given catalytic reaction. In some cases, these catalysts exhibit higher activity and/or selectivity than their analogous molecular complexes.

A possible prebiotic synthesis of purine, adenine, cytosine, and 4(3H)-pyrimidinone from formamide: implications for the origin of life

The synthesis of prebiotic molecules is a major problem in chemical evolution as well as in any origin-of-life theory. We report here a plausible new prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide under catalytic conditions. In the presence of CaCO 3 and different inorganic oxides, namely silica, alumine, kaolin, and zeolite (Y type), neat formamide undergoes the formation of purine, adenine, cytosine, and 4(3H)-pyrimidinone, from acceptable to good yields. The role of catalysts showed to be not limited to the improvement of the yield but it is also relevant in providing a high selectivity in the products distribution.

Pervaporation of alcohol–water and dimethylformamide–water mixtures using hydrophilic zeolite NaA membranes: mechanisms and experimental results

Dehydration of solvents using hydrophilic polyvinylalcohol pervaporation membranes is a well-established technology. However, these polymeric membranes may not be suitable for applications involving high water concentrations or applications containing harsh solvents like dimethylformamide due to membrane stability problems and swelling effects. These applications are commonly encountered in the pharmaceutical industry. The recent development of solvent and temperature-resistant, hydrophilic zeolite NaA membranes has made it possible to overcome the above limitations of hydrophilic polymeric membranes. In this study, experiments were conducted with various alcohol–water (methanol–water, ethanol–water, isopropanol–water) mixtures and with dimethylformamide–water mixture over a wide range of temperatures (25–70°C) and solvent concentrations (0–100 wt.%). The total flux for ethanol–water mixture was found to vary from 2 to 0.05 kg/m 2/h at 60°C as the feed solvent concentration was increased from 0 to 100 wt.%. The total flux for methanol–water and isopropanol–water mixtures was observed to vary from 2 to 0.15 and 2 to 0.21 kg/m 2/h, respectively, as the alcohol concentration was changed from 0 to 100 wt.% . The total flux was also found to remain approximately constant up to 70 wt.% alcohol in the feed. Both water to ethanol and water to isopropanol separation factors were observed to lie between 1000 and 5000 over a wide range of solvent concentrations. The water to methanol separation factor was found to lie in the range of 500–1000. The total flux behavior was also found to be very similar for the other solvent–water mixtures such as acetone–water and ethyl acetate–water. The ionic Na + sites in the NaA zeolite matrix play a very important role in the water transport through the membrane. These sites act both as water sorption and transport sites. The surface diffusion of water occurs in an activated fashion on these sites. The precise micropore structure of the zeolite cage helps in a partial molecular sieving of the large solvent molecules leading to high separation factors. The zeolite membrane active layer may contain certain non-zeolitic interstitial pores with preferential water sorption. One of the reasons for the high hydrophilicity of zeolite NaA is the strong electrostatic interaction between ionic sites and the water molecule (due to its highly polar nature). A high degree of hydrophilicity of the zeolite membrane is suggested from a pure water sorption value of 0.6 g/g zeolite. The detailed interpretation of this result, however, requires consideration of both true zeolitic microcavity uptake as well as interstitially held water between crystallites. Any molecule highly polar in nature (indicated by a high dipole moment or dielectric constant) is expected to strongly interact with the ionic sites in the cage. In fact, this effect was indirectly observed for the dimethylformamide–water mixture. The water flux in this case, was found to be lower than that for alcohol–water mixtures thus indicating the possibility of competitive sorption of dimethylformamide molecules on the zeolite sites. A linear correlation was found to exist for the pure water flux through the membrane and the partial pressure driving force of the water. The other alcohol–water mixtures followed this trend reasonably well. The use of zeolite membranes for dehydration of complex solvent streams has been actually demonstrated by experiments with a synthetic ethyl acetate mixture. Thus, the use of inorganic zeolite membranes for difficult solvent separations seems to be very attractive.

A homochiral metal-organic porous material for enantioselective separation and catalysis

Inorganic zeolites are used for many practical applications that exploit the microporosity intrinsic to their crystal structures. Organic analogues, which are assembled from modular organic building blocks linked through non-covalent interactions, are of interest for similar applications. These range from catalysis, separation and sensor technology to optoelectronics, with enantioselective separation and catalysis being especially important for the chemical and pharmaceutical industries. The modular construction of these analogues allows flexible and rational design, as both the architecture and chemical functionality of the micropores can, in principle, be precisely controlled. Porous organic solids with large voids and high framework stability have been produced, and investigations into the range of accessible pore functionalities have been initiated. For example, catalytically active organic zeolite analogues are known, as are chiral metal-organic open-framework materials. However, the latter are only available as racemic mixtures, or lack the degree of framework stability or void space that is required for practical applications. Here we report the synthesis of a homochiral metal-organic porous material that allows the enantioselective inclusion of metal complexes in its pores and catalyses a transesterification reaction in an enantioselective manner. Our synthesis strategy, which uses enantiopure metal-organic clusters as secondary building blocks, should be readily applicable to chemically modified cluster components and thus provide access to a wide range of porous organic materials suitable for enantioselective separation and catalysis.

Organic host–guest molecular assemblies

The utility of materials possessing molecular-scale porosity has been amply demonstrated by the use of inorganic zeolite frameworks as functional catalysts, separating media, and novel electronic materials. This has prompted an increase in the development of porous organic host materials capable of including guest molecules within their pores, thereby mimicking the behavior of inorganic zeolites. Such organic host–guest complexes may prove to be superior to their inorganic counterparts in some applications because they are formed spontaneously by self-assembly from molecular building blocks that can be customized through organic synthesis, yielding host structures in which the pores have precisely defined size, shape and composition. However, in order to design and synthesize host–guest complexes possessing unique and useful properties it is essential to control the assembly of molecules into preordained, desirable solid-state architectures. Understanding how molecules arrange in the solid state and using this information rationally to ‘engineer’ solid-state properties is essential to numerous technologies, including electronics, optoelectronics, sensors, information storage, and chemical separations.

Nanoporous and mesoporous organic structures: new openings for materials research

Organic solid state and molecular architectures providing nano- or mesoporous space for the inclusion of guest species open up new opportunities for the synthesis of materials showing designed chemical and physical properties. Porous materials are reviewed by taking into account recent progress in inorganic zeolites, metalloorganic and organic networks including carbon nanotubes and condensed cyclodextrins. Various properties requiring a parallel alignment of close-packed guests are addressed. As a particular example of physical property design, spontaneous polarity formation in channel-type inclusion compounds is discussed.

Surface organometallic chemistry: some fundamental features including the coordination effects of the support

The study of the various kinds of reactions between organometallic complexes and the surfaces of inorganic oxides, metals or zeolites constitutes a new aspect of the coordination chemistry on surfaces. In this non-exhaustive and short review article, we would like to try to answer a few questions regarding this area of coordination (or organometallic chemistry) which may have some future impact in the field of catalysis. The questions that we would like to answer are the following: Are the basic rules of molecular organometallic and coordination chemistry valid when one tries to apply them to surfaces? One can wonder whether or not the functionalities which are present at the surface of an oxide, M x O y (M–OH groups, strained M–O–M groups and MO, aso) have a chemical reactivity which can be predicted on the basis of molecular chemistry. A few selected examples will be given about the reactivity of tin, rhenium or zirconium alkyls with the silanol groups of partially dehydroxylated silica. Can we obtain reliable and precise informations when some selected tools of surface science and molecular organometallic chemistry are applied simultaneously to elucidate the structure of surface organometallic fragments? One can reasonably expect that the way the surface organometallic fragments coordinate to the surface can be rationalized on the simple rules of coordination chemistry (electron counting, formal oxidation state). A few examples will be given regarding the surface structure of silica-supported zirconium hydrides or rhodium allyls. Is it possible that a well chosen surface organometallic fragment represents an intermediate in heterogeneous catalysis? If one can study the reactivity of a well chosen surface organometallic fragment, then one is in a position to demonstrate some elementary steps of heterogeneous catalysis. In this review we shall consider the surface reactivity of supported rhodium allyls or tin alkyls. What kind of mobility can we expect from surface organometallic fragments? In sharp contrast with discrete ligands of molecular chemistry, surfaces of oxides obviously provide a so called “pool of oxygens” which binds the surface organometallic fragments in a localized manner. However, due to its almost infinite structure, such a “pool” is obviously responsible for surface mobility, which is also a key parameter in certain catalytic processes (sintering, diffusion processes, reconstructions, leaching,⋯). Examples will be given on the mobility of Rh I(CO) 2 grafted onto a silica surface. The organometallic fragments are also mobile around the metal carbon bonds and this phenomenon can be evidenced by solid-state nuclear magnetic resonance (NMR) and can have applications in molecular separations and on the reactivity of the organometallic complexes. In each case, the role of the support as a coordinating ligand is a key factor of this chemistry.

Strontium binding properties of inorganic adsorbents

A comparison of strontium sorption on synthetic inorganic ion exchangers and zeolites from 0.01M CaCl2 solution, sea water and an artificial foodstuff fluid has been carried out in batch and column experiments. It was found that some adsorbents among the groups manganese dioxides, mixed titanium-manganese oxides, antimony-based materials and synthetic zeolites had the highest selectivity to strontium (K d >1000). These adsorbents are interesting for further investigation concerning their use for radiostrontium decontamination of foodstuffs (if nontoxic), as well as for analytical purposes.

Tailoring the Pore Size of Hypercrosslinked Polymer Foams

AbstractOrganic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability and processing. Rigid molecular foams or “organic zeolites” would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with p-dichloroxylene (DCX) or divinylbenzene (DVB) as the crosslinking agent. Transparent gels are formed suggesting a very small pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15g/cc to 0.75g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m2/g with pore sizes ranging from 6Å to 2,000Å. Further evidence of the uniformity of the foams and their pore sizes has been confirmed by high resolution TEM.

Starch‐Derived Products for Detergents

AbstractRecent developments in the formulation of detergents have been driven by a strong consumer demand for natural and biodegradable products. Detergent manufacturers responded to this demand with corresponding products and advertising slogans such as “fully biodegradable”, “natural” or even “double natural” to oust their competitors. In a detergent formulation, starch‐ derived products can in principle be used for the following purposes: as the hydrophilic head group in surfactants, as the starting material for (poly)carboxylate co‐builders and as the backbone of bleaching activators. Non‐ionic classical surfactants can be replaced by alkylpolyglucosides (APGs), a class of products completely based on renewable resources such as glucose and fatty alcohols derived from natural fatty acids. Sodium tripolyphosphate (STPP), the product responsible for the eutrophication of surface waters, can be substituted by a combination of an inorganic zeolite and highly oxidised starch (dicarboxylic starch) or by citrate. Acetylated polyols derived from hydrogenated carbohydrates such as sorbitol can take over the function of the petrochemically‐based tetraacetyl ethylene diamine (TAED) used as activator to allow perborate bleaching at lower washing temperatures.

Modified embedding procedure for microtomy of large particle zeolites

A method is described to strengthen the binding of organic resin to inorganic zeolite, allowing large particles to be microtomed. For FeZSM-5 aggregates the particle size limit increased from 3 microns to greater than 20 microns in diameter by application of this method. This technique can be applied to a variety of oxide powder samples, extending the utility of microtomy as a materials science tool.

Microtomy of Large Particle Zeolites for Tem

ABSTRACTUniformly thin specimens of powders, suitable for electron microscopy, can be prepared by ultramicrotomy. There is a size limit to the particles that can be studied since larger particles tend to be dislodged from the available resins when microtomed. A method is described to strengthen the binding of the organic resin to the inorganic zeolite, allowing large particles to be sectioned. The particle size limit increased from 3 μm to greater than 20 gim in diameter for FeZSM-5 aggregates. This method can be applied to a variety of oxide powder samples, extending the utility of microtomy as a materials science tool.

The heat capacity of water near solid surfaces

Anomalous heat capacities of water at solid/water interfaces have been obtained. The solids vary from inorganic (zeolites, porous class, silica gel, activated carbon) to biological (protein lysozyme and adrenal gland). Water heat capacities at all interfaces exhibit the same pattern. At room temperature the small values are close to ice and increase with temperature, reaching the value of free water between 380 and 440 K.

Binding and Oxidation State of Uranium in Recent Phytogenic Sediments, Peats, and Lignites of Selected Areas, Influenced by Physico‐Chemical Parameters

AbstractThe high bog plateau “Drei Horste” at Lake Oderteich in the Upper Harz Mountains (Western Germany) shows uranium(VI) being dissolved from a granitic bedrock and transported by oxidizing waters containing humic and fulvic acids. Uranium(VI) is deposited in phytogenic sediments and in peat layers. In the sediments the concentration of uranium correlates with the content of functional acid groups. The binding between the organic substance and uranium is based on ion exchange, as shown by experiments with fractions of different isolated humic substances. – Uranium in lignites from “Date Creek”, Arizona, USA shows a significant correlation to organic carbon. The proceeding coalification from peat to lignite causes a change in the binding of uranium: uranium in organic binding is to be observed in low grade ores (<0.1% U) only. High grade ores (>0.1% U) have uranium in inorganic binding mainly. The oxidation state in organic low grade ores is controlled by their contents of organic reductants and of humic acids. Prerequisites for the formation of high grade ores in “Date Creek” were a low E vs. SHE‐level (formation of coffinite) and an availability of organic (humic acids) and inorganic (zeolites) exchange sites for the remaining portion of uranium(VI).

Use of γ-zirconium phosphate for Cs removal from radioactive waste

Radiation stability of synthetic organic ion-exchange resins is not sufficient for the processing of very highly radioactive solutions because these solutions cause significant changes in the capacity and selectivity by hydrolysis of functional groups, chain scission and changes in degree of crosslinking1,2. Among the inorganic ion exchangers, zeolites and clay minerals have been used in decontaminating radioactive waste solutions3–6 because of their high ion-exchange capacity, selectivity and presumably their radiation stability7; however, their use is limited because of their instability in mildly acid solutions1. Another class of materials—insoluble acid salts formed by polybasic acids and certain hydrolysable polyvalent cations— also possess cation exchange properties. These salts include phosphates, arsenates, tungstates and molybdates of zirconium, thorium, titanium and other metals2. Among these insoluble acid salts, zirconium phosphate gels have been investigated8 very extensively. Crystalline phases of zirconium phosphate were first prepared in 1964 and 1968 from gels on refluxing in phosphoric acid by Clearfield and co-workers9,10. We report here the discovery of crystalline γ-zirconium phosphate as a highly selective caesium ion sieve which can be used to separate 137Cs from accident waste water or from circulating water in nuclear reactors.

ChemInform Abstract: MODIFIED ZEOLITES. PART 2. SORPTION BY DEALUMINATED, SILANATED MORDENITES

Chemischer InformationsdienstVolume 10, Issue 1 Physical Inorganic Chemistry ChemInform Abstract: MODIFIED ZEOLITES. PART 2. SORPTION BY DEALUMINATED, SILANATED MORDENITES R. M. BARRER, R. M. BARRERSearch for more papers by this authorJ.-C. TROMBE, J.-C. TROMBESearch for more papers by this author R. M. BARRER, R. M. BARRERSearch for more papers by this authorJ.-C. TROMBE, J.-C. TROMBESearch for more papers by this author First published: January 2, 1979 https://doi.org/10.1002/chin.197901035Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume10, Issue1January 2, 1979 RelatedInformation