The transformation of butanes over H-ZSM-5, Zn-ZSM-5, and Ga-ZSM-5 at 773 K were studied with special emphasis on the activation mechanism of butanes. Over H-ZSM-5, butanes undergo cracking exclusively by a carbonium-ion mechanism at low conversion levels. At higher conversion levels, the activation by a hydride-transfer mechanism are involved. The loading of Zn and Ga greatly enhances the dehydrogenation of starting alkanes as well as intermediate alkenes. The loading of the metal cations promotes also the cracking, especially in the case of isobutane. The synergetic action of the metal cations and protons is proposed as a mechanism of alkane dehydrogenation.

There are a series of reactions such as isomerization, alkylation, dimerization of olefins, condensation, etc, which are catalyzed by bases. Solid base catalysts are competitive with respect to solid acid catalyst for carrying out reactions which can be catalyzed by either acids or bases. Solid bases can successfuly catalyze transformations of organic substrates containing heteroatoms, such as N, O, and S. Solid acids, which can also catalyze these reactions, often are poisoned by those substrates. Moreover, in some cases, such as olefin and alkyne isomerizations, it is possible by using bases to achieve stereochemical control. This has impulsed researches to look for very strong solid base catalysts, i.e., superbasic solids, such as supported alkaline metals. These, while active at moderate temperatures, present a major drawback derived from their relatively low stability and frequent catalyst regenerations. However, there are a significant number of interesting reactions which can also be catalyzed by bases with medium strength. In this case, the use of a very strong base catalyst can be disadvantageous because it can also catalyze other, non desired, more demanding reactions, with the corresponding decrease in selectivity to the desired product. Furthermore, in some processes, it can become more critical to adequately control the acid-base pairs than to achieve a very strong type of basic sites.

Zeolite catalyts have acquired considerable technical and economical importance in refinery technology and petrochemistry. Over the past ten years, the search for applications of zeolite catalysis in the synthesis of organic intermediates and fine chemicals has been stepped up. An important aspect in this development is the changeover of reactions carried out over homogeneous catalysts to heterogeneous zeolite catalysis.

From this range of applications, it is intended to present two selected processes. These are the synthesis of pivalic acid and -caprolactam. The dependence on test parameters and on the catalyst properties such as acidity and doping, is described. A comparison is made with the conventional process carried out industrially. The advantages and disadvantages of the zeolite-catalyzed process are weighed up against one another.

The production of ε-caprolactam and pivalic acid by heterogeneous catalysis over zeolite catalysts offers a genuine alternative to the industrial processes employing homogeneous catalysis, particularly from the point of view of environmental protection, since the use of toxic BF3 and NH2OH as well as the inevitable coproduction of ammonia sulfate is avoided.

The Co(III) form of cobalt-substituted aluminophosphate molecular sieves, Co(III)-APOs, was found to be a selective oxidant for a variety of organic and inorganic compounds. At relatively low temperatures (20 to 100°C), alcohols are converted to aldehydes and ketones, benzene becomes a dimer radical cation, amines are transformed to imines, and NO is oxidized to NO+. There is also evidence that Co(III)APOs activate the C-H bonds of methane at higher temperatures (400–500°C). Accompanying all these reactions is a clearly observable change of color from the yellow of the Co(III) form to the blue of the Co(II) form.

The directing effect of fluoride anions in the synthesis of molecular sieves seems to be related to the strength of its interaction with the framework. For example, whereas F is bridging 2 Al atoms of a four-membered ring in AlPO4-5 containing tetrapropylammonium fluoride and in an new triclinic morpholine-containing chabazite-like AlPO4, it is found in double four-rings in three other phases which were synthesized recently. Firstly in the tetragonal all-silica AST-type octadecasil (space group I4/m, a = 9.194(2)Å c = 13.396(4)Å) which was obtained in the presence of quinuclidine and HF. Secondly in two novel cubic microporous gallophosphates which are formed selectively in the presence of hydrofluoric acid. One has the structure type LTA (space group Fm3c, a = 24.0354(1)Å) and crystallizes with di-n-propylamine as a template, and the other shows a novel structure type (space group Fm3c, a = 51.84Å) with a 3-dimensional 20-membered ring channel system. This is the largest membered ring ever reported for a synthetic material.

Diffuse reflectance spectroscopy (DRS) is an excellent technique for the investigation of the synthesis process of CoAPO-5. The DRS intensities increase concomitantly with the crystallinity during synthesis. DRS is also useful in the characterization of the nucleation stage. The transition from an aluminophosphate-hydrate to a non-hydrated structure is observed.

The series of layered double hydroxides, MgnAl(OH)2n+2X (n = 2–5, X = NO3− or Cl−) and NinAl(OH) 2n+2X (n = 2–4, X = NO3− or Cl−), were pillared with polyoxometalate ions of the Keggin structure, ranging from [PW12O40]3− to [PV4W8O40]7−, in aqueous solution. Full exchange of the Keggin ions into the layers is achieved as evidenced by X-ray powder diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Also, partial exchange was observed for Ni5Al(OH)12NO3 The key factor that effects these reactions is the pre-swelling step. Thus, when the layered double hydroxides are thoroughly wet either by preparing wet solids or by soaking the dried products for an extended period, pillaring reactions proceed with great ease. Relations can be extracted between the water content and the separation between the layers, as well as between layer charge density and the charge of the Keggin ion. The pillared layered double hydroxides were found generally to have interlayer distances ranging from 11.0 to 13.5 Å, which is smaller than the numerical sum of the Keggin ion diameter and the ideal thickness of the hydroxide layer. This fact and the low crystallinity are attributed to strong interaction between the basic layered double hydroxides and the acidic Keggin ions. A more crystalline phase with the expected 14.5 Å interlayer spacing was also obtained as a mixture with the lower spaced products.

Polymeric hydroxy-Al cations were introduced into the interlayer of acid-activated montmorillonites by cation exchange. The resulting pillared materials possessed layer spacings of 18 – 20 Å, surface areas between 250 – 320 m2/g, pore volumes in the range 0.3 – 0.38 cc/g and pore diameters in the range 32 – 40 Å depending on preparation procedures (i.e pillaring temperature and drying method). Powder XRD analysis indicated that the pillars formed were stable to temperatures above 500 °C. The surface acidity of these type of pillared clays was higher than that of pillared non-activated clays. Preliminary studies on their adsorption capacity for chlorophyll showed that they were superior to pillared non-activated clays.

Homoionic-montmorillonite-p-aminoazobenzene intercalation compounds were prepared by novel solid-solid reactions at room temperature. When Na-, Ca- and Ni-montmorillonites were used as host materials, the absorption maxima of p-aminoazobenzene changed considerably upon intercalation, causing the difficulty of studying photochemical behavior of the intercalated dyes. The n-dodecylammonium-montmorillonite-p-aminoazobenzene intercalation compound gave an absorption spectrum similar to that observed for p-aminoazobenzene dissolved in benzene. The intercalated paminoazobenzene in the interlayer space of n-dodecylammoniummontmorillonite exhibited reversible cis-trans photoisomerization by irradiation of UV light.

The H2O3PCH(C6H4)2CH2PO3H2 and H2O3PO(C6H4)2OPO3H2 acids were synthesizedT and used to obtain new pillared zirconium phosphonates and organic phosphates in which the pillars are tilted with respect to the layers. The Zr(O3PCH2(C6H4)2CH2PO3) and Zr(O3PO(C6H4)2OPO3) obtained have a good thermal resistance and the distance between the inorganic α-layers joined by the organic pillars is 14.7 and 13.8 Å, respectively. Structural models suggest that the biphenyl groups in the solids are tilted at 140° and 137° with respect to the perpendicular at the layer plane. Solid solutions of the two derivatives over the whole range of composition have also been obtained; the distance between the α-layers changes from 14.7 to 13.8 Å in a continuous way as the diphosphate groups replace the diphosphonate ones, allowing us to suppose a variation of the tilting angles. Attempts to remove the phosphoester in the mixed derivatives by hydrolytic attack, and to replace some pillars with phosphite groups are described.

The presence of H3PO3 in the synthesis of zirconium diphosphonates in dimethylsulfoxide, other than the expected dilution of the pillars, which in turn gives rise to a certain degree of microporosity, may also induce the formation of a high percentag. of mesopores. E.g., compounds with high surface area(300–500 m2 /g) of which 60–70% is due to mesopores with diameters 20–40 Å and the remaining is due to micropores, were obtained. It was furthermore found that the distribution of the mesopores was fairly narrow. Compounds with micropores <3 Å and mesopores of 20–30 Å behave in practice as pure and narrow mesoporous solids;they are therefore of great interest as new molecular inorgano-organic sieves.

New results are presented concerning the topotactic self-assembly, n-type doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice n(WO3)-Na56Y, where O < n ≤ 32, built-up of single size and shape (WO3)2 dimers. In particular it has been found that the oxygen content of these dimers can be quantitatively adjusted by means of a thermal vacuum induced reversible reductive-elimination oxidative-addition of dioxygen. This provides access to new n(WO3−x)−Na56Y materials (0 < x ≤ 1.0) in which the oxygen content, structural properties and electronic architecture of the dimers are changed. In this way one can precisely control the oxidation state, degree of n-doping and band-filling of a tungsten(VI) oxide supralattice through an approach which can be considered akin to, but distinct in detail to, that found in the Magneli crystallographic shear phases of non-stoichiometric bulk WO3−x. Another discovery concerns the ability to alter local electrostatic fields experienced by the tungsten(VI) oxide moieties housed in the 13Å supercages of 16(WO3)−M56Y, by varying the ionic potential of the constituent supercage M+ cations across the alkali metal series. This method provides the first opportunity to fine-tune the band-gap of a tungsten(VI) oxide supralattice. A miniband electronic description is advanced as a qualitative first attempt to understand the origin of the above effects. The implications of these discoveries are that cluster size, composition and intrinsic electrostatic field effects can be used to “chemically manipulate” (engineer) the doping and band architecture of intrazeolite supralattices of possible interest in quantum electronics and nonlinear optics.

Pyrene is used as a molecular probe to study surface polarity, constrained character of diffusion, oxygen diffusion, effects of coadsorbed water, and exchange cations in zeolites A, X and Y. The experimental methods include both steady-state and time-resolved fluorescence spectroscopy, and diffuse reflectance absorption spectroscopy. The properties of CdS and TiO2 constructed in zeolites are also presented.

CdS, ZnS or PbS dispersions are prepared in a NaX matrix by ion exchange and gas phase sulfidation. The degree of sulfidation remains incomplete in all cases. This fact can be explained by preferential bonding of the cations to the zeolite framework and to an increase of the solubility constants for quantum-size particles. Zeolite-hosted sulfide particles grow to supra-supercage size under fragmentation of the host framework. The shift of the position of the optical absorption edge correlates with the sulfide particle size obtained from transmission electron micrographs. The rate of photocorrosion of the sulfide clusters strongly depends on the particle size between 1 and 10 nm.

PbI2 clusters confined in spaces of LTA zeolite are successfully prepared through vapour phase. An HREM image showed that the crystallinity of the zeolite was preserved after preparation and showed directly that the clusters were incorporated into the α-cages. Absorption spectra were measured by diffuse reflection method as a function of loading density of PbI2 molecules. Several absorption bands from different cluster sizes were observed and showed remarkable blue shift. At the maximum loading, extra reflections, which are forbidden for Fm3A of LTA, were observed in electron and X-ray diffraction patterns. The appearence of the extra reflections and the dependence of absorption curve on the loading density suggest that superlattice of clusters was produced. The characteristic feature of zeolites as containers to make an artificial superlattice of clusters is pointed out.

Two photocatalytic systems consisting of spatially organized electron donor/photosensitizer/oxide semiconductor/catalyst assemblies are described. The first consists of an aluminosilicate zeolite (mordenite or zeolite L) containing Pt clusters, methylviologen, and titanium oxide within the linear channels, together with a size-excluded photosensitizer RuL32+ (L = 4, 4-dicarboxy-2, 2-bipyridine) adsorbed at the TiO2 surface. The kinetics of photochemical charge separation and hydrogen evolution in the presence of sacrificial electron donors are reported. In the second system, a layered oxide semiconductor, K4−xHxNb6O17·nH2O, replaces the zeolite/TiO2/MV2+ composite. Using adsorbed RuL3 and visible light excitation, this material decomposes acidic iodide solutions into H2 and I3− with a quantum efficiency of 0.3 %.

Thin film coatings of NaY, NaA and ZSM-5 zeolites have been grown on copper and platinum substrates. Such materials have ion-exchange properties, molecular sieve pore size distribution, zeolitic surface areas and are crystalline. Size and charge selective electrodes, oxygen reduction fuel cells, and thin layer chromatography devices have been produced with these materials.

Methylviologen dication was intercalated to some layered semiconducting oxides, and the photoinduced electron transfer between the hosts and the guest was investigated. K4 Nb6O17, H2 Ti4O9, and HTiNbO5 were used as the layered oxides. The arrangements of methylviologen in the interlayers were deduced from the XRD results. UV irradiation of the intercalation compounds caused electron transfer from the hosts to the guest to form methylviologen radical cations. The radical cations were stable within a few minutes even in the presence of oxygen, and the decaying rates altered with the hosts. The difference was discussed on the basis of the structure of the intercalation compounds.

Microporous zeolite crystals were successfully coupled onto the gold electrodes of quartz crystal microbalances (QCM). A self-assembled monolayer of thiol-alkoxysilane coupling agent on the gold surface was used as the Interfacial layer to promote adhesion of the zeolite crystals to the QCM. The resulting, densely packed single layers of zeolite crystals were stable to at least 625 K. Transient sorption behavior of organic vapor pulses, dynamic vapor sorption isotherms and nitrogen sorption isotherms at liquid nitrogen temperature were examined to characterize the zeolite-coated QCMs. Depending on the type of zeolite coating, the resonance frequency response to vapor pulses could be increased up to 500-fold compared to the bare QCM. The regular micropores (0.3–0.8 nm) of the QCM-attached zeolite crystals were found to control molecular access into the extensive intrazeolite volume. Selectivity of the frequency response in excess of 100:1 toward molecules of different size and/or shape could be demonstrated. An additional recognition mechanism based upon intrazeolite diffusion rates was also established.

The intercalation properties of the layered V2O5 xerogel towards conductive polymers are described. The systems intercalated with polyaniline show post-intercalative redox polymerization caused by ambient oxygen to give products with enhanced conductivity. For the first time the role of oxygen in this intercalation reaction has been unequivocally identified. We also report the synthesis and some properties of a new intercalation compound in which the guest species is poly(ethylene oxide), an insulating polymer.