Zeolite powders

Reactants and reagents can be conveniently loaded into the dry zeolite by adsorption. This can be accomplished by intimately mixing the solid or liquid reactant and the powdered zeolite, by absorption from the gas phase, or by diffusion in a solvent slurry containing the zeolite and dissolved reactant. The choice of solvent for the slurry method is critical. It must be volatile enough to be removable at a pressure and temperature that does not result in evacuation of the reactant or its decomposition. In addition, the reactant must have a greater affinity for the interior of the zeolite than for the slurry solvent itself. The lack of affinity for the interior of the zeolite is an acute problem for non-polar hydrocarbons that lack binding sites for the intrazeolitic cations. The use of fluorocarbons such as perfluorohexane as slurry solvents takes advantage of the fluorophobicity of many hydrocarbons and has alleviated this problem to some extent.29... 

Alternatively, finely powdered zeolites may be used in detergent powders as a builder since zeolite particles smaller than 10 pm do not stick to clothing. Formerly, sodium polyphosphates (Section 7.7) were used extensively as detergent builders to tie up the Ca2+ and Mg2+ in hard water as soluble complexes (or as a precipitate that washes away). However, many communities ban phosphate detergents because of pollution problems (Sections 7.7 and 9.6), thus creating a major new market for zeolites. 

The adsorption behavior of benzene on dehydrated NaX and NaY zeolites has been investigated directly by H and 13C NMR measurements of the adsorbed benzene and indirectly by the combination of 129Xe NMR and isotherm measurements of the co-adsorbed xenon. Powdered zeolite samples of various Si/Al ratios and with varied adsorbate concentrations were investigated. Detailed macroscopic and microscopic adsorption phenomena of benzene in NaX and NaY zeolites, including the loading capacity, mobility, and sites of adsorption are presented in terms of measurements of NMR linewidths and chemical shifts. 

It is necessary to recognize that e and e, are effective values, inasmuch as we are studying powdered zeolites and not monocrystals here. 

The powdered zeolite (grain size between 0.2 and 0.5 mm) to be tested is placed between the electrodes of the capacitor, which is also the sample holder. The dielectric sensor circuit, which is fed with an alternating voltage (amplitude 0.1 V 30Hz standard commercial capacitor of known capacitance (Cs = 1 lOpF) in place of the reference capacitor (Cr) (see Figure 4.49c) [15,16,111-113,120], For the calculation of the real part of the relative permittivity, at different frequencies and temperatures, the following relation was used [15,120]... 

Table I displays values of k for granulated zeolites CaA-I and CaA-II 12) and the pressed powdered zeolite NaX 13).

Zeolite and alumina were calcined at S00°C for S h in air prior to use. A mixture of alcohol, benzyl chloride, and powdered zeolite or alumina was stirred in a nonpolar solvent (hexane or carbon tetrachloride) under reflux for S h in an inert atmosphere. After the reaction, water was added and the mixture was refluxed for 0.5 h in order to remove organic products completely from the solid surfaces. 

Eor this reason, the use of powdered zeolite is not possible in a process. That is why Rhodia used as a catalytic phase a zeolite HBEA mixed with alumina in order to shape the solid. On an industrial scale, the catalyst can be used as pellets or extrudates which have the most advantages in terms of efficiency and ease of use. 

Reaction conditions molar ratio anisole benzoyl chloride = 4, 2.5 wt% of powdered zeolite/anisole. Temperature 125 duration 4h. 

The cobalt supported zeolite catalyst was prepared by ion exchange. Powdered zeolite A was slurried in distilled water, and an aqueous solution of Co(N0j)2.6H20 was added dropwise over a period of five hours with stirring and gentle heating. The saiple was then filtered and air dried at room temperature. 

Nitrogen adsorption properties of typical samples, amorphous sinter, powder zeolite ZSM-35 and zeolite ZSM-35 disc, were measured on a Micromeritics ASAP 2000 at 77k. According to the pore diameter distribution curve in fig.3, zeolite ZSM-35 disc had similar micropore to powder zeolite ZSM-35. Results can be seen from Table 6, the pore diameter of zeolite ZSM-... 

When the sample is the powder zeolite mixed with silica-alumina (60% weight of zeolite, length 25 mm), the benzene concentration profiles (Figure 5-a) present an adsorption fi ont which lasts more than 30 min. On one hand, the intercrystallite diffiision rate is decreased by the presence of the mesoporous silica-alumina, on the other hand benzene also adsorbs on the silica-alumina. In the case of a compressed mixed sample (length 12 mm) the profiles are rectangular as... 

Large coffin-shaped zeolite H-ZSM-5 crystals have been chosen as suitable model systems to study the structural motifs and related intergrowth structure, which are also present in smaller powdered zeolite materials used in industrial catalysis. The advantage of large model crystals, which can be prepared with adjustable Si/Al ratio and size, is that the catalytic properties of each growth unit of a zeolite can be studied separately by means of optical microscopy methods, such as UV-vis microspectroscopy and confocal fluorescence microscopy [114, 122]. As both microspectroscopy methods obey the optical Abbe diffraction limit, features can be studied in the size of approximately X/2. The resolution d of an optical microscope is given by... 

The solvents were dried over molecular sieve 3A. The zeolites Linde 13X (abbreviated as NaX) and Linde 13Y (NaY) were purchased from Shokubai Kasei Co., Ltd. Various ion exchanged zeolites were prepared according to the ion exchange technique Powdered zeolite (100 g) was immersed in an aqueous 0.5 M solution of the corresponding metal chloride (1000 ml) at 70 for 3 h, and then the aqueous solution was decanted off. This procedure was repeated 10 times. Next, the ion exchanged zeolite was washed with deionized water until no chloride ion was detected in the filtrate, and dried at 110 for 10 h, then at 500 C for 5 h... 

Finally, powder zeolite substitutes zeolite suspension almost completely. This brought a flowability standard. 

Bionanocomposites based on SPI reinforced with bentonite, talc powder, zeolite, and rectorite have also been reported in the literature [212-214]. In most cases, they had improved mechanical and barrier properties as compared to unfilled matrices. 

Differential heats of adsorption polar and apolar small molecules HpO, CH,OH, CO , powdered zeolites) Na , RaA,... 

Catalytic cracking is a key process used to increase the quality and quantity of gasoline fractions. The most commonly used process is the fluid bed type, which uses a finely powdered zeolite catalyst that is kept in suspension in the reactor... 

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