Showing papers in "Zeolites in 1988"

TL;DR: The proposed framework structures are consistent with the known diffraction, sorption, and cation-exchange properties of zeolite beta.

TL;DR: In this paper, the chemical shift of 129 Xe adsorbed on a zeolite is the sum of terms corresponding to the different perturbations to which it is subjected.

TL;DR: In this article, a new experimental technique was developed for measuring the intracrystalline diffusivities of strongly adsorbed species by following chromatographically the desorption curve for a small sample of zeolite, saturated at a low concentration level.

TL;DR: In this paper, the adsorption properties of a novel family of aluminophosphate based molecular sieves denoted as VPI-5 are described, which are the first to contain pores larger than 10 A. The large pores of these sieves consist of channels circumscribed by eighteen membered rings and possess free diameters of approximately 12.

TL;DR: In this article, the authors proposed a method for catalytically reducing one or more nitrogen oxides from a gaseous stream, where the microporous molecular sieve composition is (i) optionally acid treated with an inorganic or organic acid, (ii) hydrogen-forming cation exchanged, prior to said contacting in said method, and wherein at least a portion of excessive ammonia in such a method is oxidized without substantial adverse effect on catalytic reduction.

TL;DR: In this article, a study of the synthesis of zeolite SSZ-13 (a high-silica chabazite) from sodium silicate solutions showed the transient formation of Cubic P zeolites.

TL;DR: In this article, the acid sites of aluminophosphate (AlPO-5) and silicoaluminoph phosphate (SAPO-5)-sieves have been investigated using diffuse reflectance i.r.d. spectroscopy, temperature-programmed desorption (t.p.d.) of NH 3, and catalytic activity in the cracking of cumene and oligomerization of ethylene.

TL;DR: In this paper, diffusion coefficients were measured for the C 1 to C 5 normal paraffins in silicalite using a molecular sieve membrane and the coefficients were found to correlate directly with the carbon number of the diffusant.

TL;DR: The efficiency of the synthesis of zeolite BETA and the chemical composition of the crystals depend very much on the concentration of aluminium in the liquid phase, the SiO2/Al2O3 ratio of the gel particles, the presence of ethanol in the system, and the synthesis temperature as mentioned in this paper.

TL;DR: In this paper, Si MAS n.m.r. spectra are presented for highly siliceous samples of zeolites KZ-2, ZSM-12, and Beta.

TL;DR: In this paper, the authors used 57 Fe Mossbauer spectroscopy to study the ZSM-5-type structure of a tetrahedral Fe(III) and showed that > 90% of the iron in these samples is in the framework sites.

TL;DR: In this article, a correlation was developed between the ring sizes and average T-O-T angles present in zeolites, with the prominent oxygen-bending frequency observed in the Raman spectra of these materials.

TL;DR: In this article, a bridged hydroxyl forming a strained intramolecular hydrogen bond with a neighboring oxygen atom was detected and properties of the new type of hydrogen bond were investigated.

TL;DR: In this article, a model for the framework topology of the novel zeolite EU-1 was proposed based on electron diffraction, model building, subsequent DLS refinement, and a limited Rietveld refinement of the X-ray powder diffraction data.

TL;DR: In this paper, the existence of two benzene-adsorbed species has been shown by i.r. spectroscopy on (Cs,Na)X zeolites with various cesium loadings.

TL;DR: In this paper, the influence of the reaction conditions, concentration of reactants, number of treatments, and time and temperature of reaction on the final properties of the products has been studied.

TL;DR: In this article, the diffusion of a series of linear paraffins and cyclohexane in 13X and 5A zeolite crystals has been studied by the recently developed zero length column (ZLC) method.

TL;DR: In this article, a hysteresis loop was observed for sorbate loadings greater than 4 molecules per u.c. The isosteric heat of adsorption was ~ 80 kJ mol−1, and the differential molar entropy indicated an increase in ordering of the sorbed phase with increasing coverage.

TL;DR: The solid-state interaction of HZSM-5 with FeCl 3 results in the migration of Fe(III) ions in cationic positions of zeolite.

TL;DR: Binderless zeolite L particles are prepared by a method in which particles are formed from silica and from 0 to 95 wt % preformed zeolate L crystallites, and the particles are thereafter reacted with an alkaline solution comprising a source of alumina to convert the silica binder to zeolate l and may be used as catalyst as mentioned in this paper.

TL;DR: In this article, the synthesis of AIPO4-2H2O has been studied and it is shown that substitution of atoms into this intermediate may be the critical step in determining the levels of substitution into the framework of substituted amines.

TL;DR: In this paper, the diffusion of benzene in large crystals of both natural faujasite and NaX zeolite has been measured by conventional gravimetric methods and by the new zero length column chromatographic method.

TL;DR: In this article, the intrinsic electronic properties of 33 zeolite structure types with hypothetical SiO 2 composition were estimated by the Electronegativity Equalization Method and the average electronegativity and the connectivity-dependent partial charges for silicon and oxygen were calculated.

TL;DR: In this article, a mixture of solid alkaline chlorides MeCl (Me = Li, Na, K, Rb, Cs) and NH 4 -ZSM-5 or H-ZSM -5 react at elevated temperatures to evolve gaseous hydrogen chloride and form the respective cationic form of ZSM.

TL;DR: In this article, the rotational dynamics of the enclathrated molecules (1 molecule/supercage) were assessed from the widths and shapes of deuteron liquid and solid-type spectra of propene and benzene sorbed in NaX and partially silver-exchanged NaX zeolites.

TL;DR: The catalytic activity of ZSM-5 zeolite for the conversions of propane, pentane, hexane, and heptane and the isomerization of o-xylene were examined as a function of the temperature of the pretreatment of the zeolites.

TL;DR: In this article, the dependence of the chemical shift δ on the xenon concentration for each value of C and that of ° on C at Xe = 0 was studied, which can be generalized to all adsorbed phases in any zeolites.

TL;DR: The hydrothermal growth of large monocrystals of TPAZSM-5 zeolite up to 420 μm is reported in this article, which consist of fully crystalline and pure zeolitic phases with good homogeneity of the crystal sizes.

TL;DR: In this article, a compound adsorbent bed containing particles of a zeolitic molecular sieve having pore diameters of at least 3.0 Angstroms was used to remove mercury from fluid streams.

TL;DR: Combining PIGE, EDX, AA, and thermal analyses with solid-state 29Si-n.m.a.r spectroscopy, the amount of SiOR and (SiOAI)−R+ groups (R H, M, TPA) was determined.