Showing papers in "Zeolites in 1982"

TL;DR: In this paper, the frequency of all the lattice OH groups in hydrogen zeolites has been rationalized in terms of two concepts: (i) frequency of the unperturbed OH groups vibrating in structural elements larger than eight-membered rings is linearly correlated with the Sanderson intermediate electronegativity of the zeolite, which in its turn varies with the chemical composition.

TL;DR: In this paper, the high resolution magic angle spinning 29 Si n.m. spectra of a number of dealuminated and ultrastable Y-zeolites have been studied.

TL;DR: In this paper, transalkylation of ethylbenzene was found to be a suitable test reaction for measuring the Bronsted acidity of zeolites, and the rate decreased with increasing size of the alkaline earth ions.

TL;DR: ZSM-5 zeolites have been synthesized using triethyl-npropylammonium (TEPA) cations as the source of the organic base X-ray diffraction, framework ir spectroscopy, scanning electron microscopy, adsorption of n-heptane and cyclohexane and product distribution in the conversion of methanol to hydrocarbons have been utilized in characterizing the synthesized zeolite as discussed by the authors.

TL;DR: In this article, a method for enhancing the activity of a crystalline zeolite, including a Zeolite having a silica-to-alumina ratio greater than 100, is presented.

TL;DR: In this paper, high resolution 13 C-n.m.r. spectroscopy can be performed in the solid state by taking advantage of 1 H- 13 C cross-polarization (CP) and magic angle spinning (MAS).

TL;DR: In this article, the adsorption of water, methanol, benzene, and n-hexane on a series of HZSM-5, in which SiO2/Al2O3 ratio was varied from about 50 to 900, were measured at 100°C, and their hydrophobic natures were examined.

TL;DR: The most probable distribution of ions indicates the presence of four cation sites; one at the centre of the hexagonal prism, two in the large cage along the diagonal, and the fourth near the 8-ring window which is split into two sites close to each other in the monovalent exchanged forms as mentioned in this paper.

TL;DR: In this paper, the structures of dehydrated Li-X and Li-Y tetrahedra were determined using X-ray powder diffraction techniques using 2.471 and 2.459 nm respectively.

TL;DR: In this article, it was shown that transformation of zeolite A into zeolites P takes place by nucleation and crystal growth from the solution, and that particles of Zeolite P consist of small crystallites of uniform size.

TL;DR: In this article, the authors studied the effects of using different silica and TPA sources in the synthesis of ZSM-5 using relatively high (Me 2/ n ) 2 O/(TPA) 2 O ratios (12/4.5) in the starting batch composition, as this compositional region has not been investigated previously.

TL;DR: In this article, it was shown that the existence of surface barriers is not a general peculiarity of zeolite crystallites, however, different ways of pretreatment as well as the preadsorption of other molecular species may lead to the formation of surface resistances.

TL;DR: In this article, the results of investigations on sedimentary zeolites in Hungary have been reviewed; some typical samples are characterized, and determination of the zeolite content with CO2 adsorption is described.

TL;DR: In this article, the influence of NaCl and retention times on the degree of zeolitization is discussed for different NaOH concentrations, and the SiO2/Al2O3 ratio zeolites ZK-19 and phillipsite appear after long induction periods.

TL;DR: In this paper, the reducibilities of nickel ions in these zeolites were evaluated by hydrogen consumption measurement, and it was assumed that the reduction was mainly affected by both the occupying sites of the nickel ions and the acidic hydroxyl groups in zeolite.

TL;DR: In this article, the electron distribution in the cages after ion-exchange with that of the parent chabazite indicates the presence of three chief cation sites: two in the large cage alone the [1 1 1] diagonal and one located near the 8-ring window.

TL;DR: In this paper, experiments were performed on Al-bearing Na-silicate solutions, with or without addition of tetrapropylammonium (TPA) and alkali cations.

TL;DR: In this article, Broussard and Shoemaker, and Smolin et al. used X-ray diffraction methods to reveal and refine the interstitial Na and H 2 O sites.

TL;DR: In this paper, it was shown that adsorption of C 2 -C 5 alcohols, ethers and olefins on H-Z-79 and H-Y zeolites results in the formation of oligomers adsorbed on Bronsted acid centres They are intermediates in the conversion to aromatics.

TL;DR: In this article, the use of zeolite N36 as a soil conditioner in tomato-growing has been investigated and the results showed that the addition of N36 resulted in an average yield of tomato higher than 50% in comparison with the control plant.

TL;DR: In this paper, the charge distribution obtained by semi-empirical quantum chemical methods for the clusters Na+[Si5AlO6H12]−, Na+ [Si3Al3O6h12]3− and Na+][Si4Al4O14H12]-4− for the corresponding cation free clusters is discussed critically and comparison is made with previous results.

TL;DR: The structure of nepheline hydrate I, Na3Al3Si3O12·2H2O, synthesized hydrothermally at 473 K, has been determined as mentioned in this paper.

TL;DR: In this article, a method for preparing self-bonded zeolite pellets by hydrothermal treatment of preformed pumice-alkali-water mixtures is described.

TL;DR: In this article, small-angle X-ray scattering properties of these samples indicate that due to hydrothermal pretreatment, structure regions are built up whose elctronic density is different from that of zeolite.

TL;DR: A series of faujasite supported catalysts with monomodal dispersed phases of nickel, palladium, and platinum, exhibiting narrow particle size distributions, are chracterized by X.p.s. as discussed by the authors.

TL;DR: In this article, the adsorption of methane and acetylene in Na-A zeolites has been studied using neutron diffraction and the effect of the sorbed gas has been increased by using deuterated molecules.

TL;DR: In this paper, two types of Fe(III) species were found (a cationic and a hydrated oxide form) and characterized in Fe (III)NH4-Y zeolites with iron content in the range 0.3-5.8 wt %.

TL;DR: In this article, the number, nature and distribution of 29Si n.m.r. detectable species in the solutions are discussed and differences in the number and nature of the detectable species are discussed.

TL;DR: In this paper, it was found that nearly two N−3 ions per u.r.c. were occluded in the framework without destroying the crystal structure of the zeolite.

TL;DR: In this article, the adsorption of ammonia on sodium forms of A, X and Y type synthetic zeolites and mordenite was examined in the 423-573 K temperature interval in a flow apparatus using helium as carrier gas.