Linde synthetic zeolites

The linking pattern of two zeolites is shown in Fig. 16.24. They have the /I-cage as one of their building blocks, that is, a truncated octahedron, a polyhedron with 24 vertices and 14 faces. In the synthetic zeolite A (Linde A) the /3-cages form a cubic primitive lattice, and are joined by cubes. j3-Cages distributed in the same manner as the atoms in diamond and linked by hexagonal prisms make up the structure of faujasite (zeolite X). 

The nomenclature of zeolites is rather arbitrary and follows no obvious rules because every producer of synthetic zeolites uses his/her own acronyms for the materials. However, as mentioned before, at least the structure types of the different zeolites have a unique code. For example, FAU represents Faujasite-type zeolites, LTA Linde Type A zeolites, MFI Mobile Five, and BEA Zeolite Beta. The structure commission of the International Zeolite Association (IZA) is the committee granting the respective three-letter codes [4], Some typical zeolites, which are of importance as catalysts in petrochemistry, will be described in the following sections. 

Synthetic forms Beryllophosphate X, Li-LSX, LZ-210, SAPO-37, siliceous Na-Y, zeolite X (Linde X), zeolite Y (Linde Y), zincophospate X... 

Sherry, H.S. (1968) The ion-exchange properties of zeolites. IV. Alkaline earth ion exchange in the synthetic zeolites linde X and Y./. Phys. Chem., 72 (12), 4086-4094. 

The age of pressure swing adsorption (PSA) began so far as air separation is concerned in the late 1950s. The first process patent was that of Skarstrom [12]. The scientists and engineers of the Linde Laboratories were very active in this field. It is worth mentioning that the discovery of synthetic zeolite molecular sieves was... 

R. M. Barrer D. W. Breck Invented the method of zeolite synthesis. In the same year, the North-American Linde Company started the production of synthetic zeolites on a commercial scale 1956... 

The object of the present investigation was to study systematically the effect of monovalent cations on the lattice vibrations in the synthetic zeolites Linde A and Linde X. It was reasoned that mid-infrared spectroscopy might yield information on cation siting in these zeolites. 

Adsorbents were synthetic zeolites 5A and 13X, manufactured by Linde, as well as an hydrogen mordenite manufactured by C.E.C.A. (Carbonisation et Charbons Actifs, Paris) the samples were in pelletized form and contained 20 wt % binder. From crystallographic data for zeolites 5A and 13X (19) and H-mordenite (20), W0 values were computed and corrected for the presence of the binder these Wo values appear in Table I. In the same way, we also studied a microporous carbon (Cecalite)... 

The first synthetic zeolites were known as Linde Molecular Sieves but are now marketed as Union Carbide Molecular Sieves they are available from Union Carbide International Company, USA. or Union Carbide (UK) Ltd directly, or through the usual chemical suppliers, t Booklets giving detailed information on the structure, action and applications of molecular sieves are available from most suppliers of laboratory chemicals. 

Dehydration of the synthetic zeolite Linde A, Na12[(A102)i2(Si02)i2]-27H20, leaves cubic microcrystals in which the A104 and Si04 tetrahedra are linked together... 

The ion pump needs no forepump, but it is necessary to reduce the pressure initially to 10 or 10 ° Torr before turning on the pump. With care, this may be accomplished with a rotaiy oil pump, but it is often done instead with a sorption pump such as the Varian Vac-Sorb pump, in which the air in the system is adsorbed on a molecular sieve (synthetic zeolite, Linde type 5A) chilled with liquid nitrogen. This type of pump has the advantage of presenting no danger of contaminating the system with oil. 

Three examples will suffice to demonstrate this information Figure 3 shows the polyhedral units in the synthetic zeolite Linde Type A, which link to provide a three-dimensional interconnecting array of channels, Figure 4 illustrates the essentially two-dimensional system of channels in the mordenite framework, and Figure 5 shows the major channels in synthetic zeolite Linde Type L arranged as parallel one-dimensional channels and shown as a stereo pair. Table 6 lists the Atlas notations for these structures with explanations, including the symbols used in Tables 2-5. 

In 1955 Union Carbide announced the commercial availability of a number of cationic forms of two synthetic zeolites designated A and X, the latter a synthetic form of the rare mineral faujasite. At this announcement, Mobil Research and Development Corporation, as well as the research and development laboratories of other major petroleum companies, hastened to obtain samples from the Linde Division. In 1955 and 1956 Mobil began to explore the potential use of these materials as adsorbents and catalysts and also began its own program on zeolite synthesis. 

Morey and Ingerson (30). Research into the hydrothermal synthesis of zeolites was put on a systematic basis by Barrer and resulted in a number of synthetic zeolites (1,2,3, 4,5, 6, 8, 9,10,11). Linde A and X (16), ZK-5 (25), and Linde L (15) were other prominent zeolites synthesized. 

Synthetic zeolite NaPl (or Linde B) is apparently an isotype of gismondine (Figure 14) according to a recent study by Baerlocher and Meier (4). The cubic structure which was proposed earlier has been ruled out in this work. The symmetry of the NaPl framework is noncubic (despite the fact that the unit cell is compatible with cubic symmetry), and the phase appears to consist of mimetic twins. 

T his paper reviews data available by January 1970 on the crystal A structures of materials containing an aluminosilicate framework with the topology of the mineral faujasite. The nomenclature will be discussed in more detail at the end. Briefly, names will be assigned which specify the treatment applied to the 3 basic starting materials—viz., faujasite, Linde Y, and Linde X zeolites. The latter 2 are synthetic materials prepared in hydrous sodium systems, the former being richer and the latter poorer in Si. The Si,Al content of Y overlaps that of faujasite. 

X-ray diffraction patterns of Linde B zeolites are shown in Figure 2 and Table II. The similarity of the main diffraction peaks is obvious. The synthetic phases produced by various workers have been arranged in Table III to show their relationship to each other. Zeolite Bx is correlated with the cubic body-centered phases of Barrer (2) (Na-Pl) and Taylor and Roy s Na-Pc (13). The Linde B2, B3, Br and B6 phases are similar to the tetragonal body-centered phases of Barrer (2) (Na-P2) and... 

Stamires (35) investigated the effect of various adsorbed phases on the electrical conductivity of Linde synthetic crystalline zeolites type X and Y. He concluded that the potential energy barrier for cationic conduction is decreased by interaction with the adsorbed phases, but he did not investigate the dielectric response of the material. 

Fig. 1. TG and DTA traces of some synthetic zeolite types. Atmosphere air heating rate lOKmin . a zeolite Linde Y (Engelhardt EZ 150), b zeolite Linde A (Carlo Erba AnalytiCals 4A), c zeolite Linde X (Carlo Erba AnalytiCals 13X)...

Fig. 6. DTA profiles, obtained a in air or b under flowing argon, of the synthetic zeolite ZK-4, a siliceous analog of Linde A, synthesized in the presence of lithium and tetram-ethylammonium and containing both cations. Heating rate 10Kmin ...

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