Aluminosilicate Catalysts Research Articles

Catalytic conversion of mixtures of methanol and alkenes over the porous alumino—silicate HTDZ-48

Unsaturated aliphatic hydrocarbons were added to a methanol feedstock which was passed over the porous aluminosilicate catalyst HTDZ-48 at temperatures up to 450°C and a WHSV of 1.0 h −1. The alkenes acted as co-catalysts for the methanol conversion and at the same time they significantly extended the effective life of the catalyst and inhibited the formation of excessive amounts of coke. The addition of halogenated alkenes to the methanol had no effect on either the reaction, rate or the catalyst life.

Catalytic conversion of mixtures of methanol and aromatic hydrocarbons over the porous aluminosilicate catalyst HTDZ-48

Monocyclic aromatic hydrocarbons were added to a methanol feed passed over the acidic aluminosilicate catalyst HTDZ-48 at a temperature of 450°C and a WHSV of 1.0 h −1. The aromatic additives acted as co-catalysts for the methanol conversion reaction and at the same time they extended the effective life of the catalyst and promoted the formation of higher molecular weight aliphatic hydrocarbons at the expense of those of lower molecular weight.

Activity of cation-exchange forms of an aluminosilicate catalyst in the skeleton isomerization of n-pentenes

A promising way of using n-pentenes efficiently is to convert them into methylbutenes. The resources of n-pentenes in the petrochemical industry are fairly large. Natural and synthetic aluminosilicates, aluminium oxide modified with halogens, and halides of metals are of interest as promising catalysts for conversion of n-pentenes into methylbutenes. By varying the conditions of the process, on the indicated catalysts it is possible to obtain fairly high yields of methylbutenes (50-60% of the materials fed). However, practical utilization of halogen-containing catalysis is made difficult by the stringent requirements concerning drying of the fed material, and also by the need to reactivate the catalysts (by introducing a halogen) after oxidizing regenerations. Aluminosilicate catalysts (ASC) are not adversely affected by moisture in the fed material and are readily regenerated, but they are insufficiently selective. In the present work a study was made of the nature and strength of the acid centers of ASC on their activity and selectivity in skeletal isomerization of n-pentenes, and the possibility of obtaining an effective catalytic system by means of modifying and controlling the acid properties of ASC was demonstrated.

Adsorption studies by powder X-ray diffractometry: Xenon on zeolite rho

It is demonstrated that it is possible to identify by X-ray diffractometry the preferred site of adsorption of xenon on the model aluminosilicate catalyst, zeolite rho in the temperature range 40 to 252 K.

Activation of an industrial aluminosilicate catalyst with a mixture of rare-earth elements for cracking heavy gas oil

Activation of an industrial aluminosilicate catalyst with a mixture of rare-earth elements for cracking heavy gas oil

Propylene oligomerization with pillared clays

Pillared-clays, when used to oligomerize propylene in a fixed bed isothermal reactor operating at 30 – 50 atm, appear to be less active than zeolite omega and an amorphous aluminosilicate (with 78% SiO 2 and 22% Al 2O 3) catalyst, but have higher selectivity for gasoline production; formation of alkylated cyclopentane saturates was observed with these catalysts. (Zr, Al)-bentonite produces benzene, toluene and branched aromatics even at low temperatures; at high temperatures, it minimizes aromatic formation and generates less coke than bentonites pillared with aluminum clusters. Spectroscopic study of chemisorbed pyridine and pilot plant data indicate that propylene oligomerization can be catalyzed by Lewis acids. Liquid composition from chromatography data correlates well with structural parameters determined by NMR techniques.

Conversion of methanol to hydrocarbons over the aluminosilicate catalyst HTDZ‐48

AbstractMethanol and methanol containing small quantities of nitrosobenzene, p‐benzoquinone and p‐cresol were passed at a liquid hourly space velocity of 1.0 h−1 over the microporous aluminosilicate catalyst HTDZ‐48 at temperatures in the range 250–450°C. In each case the methanol was converted to hydrocarbons. The presence of nitrosobenzene caused a reduction in the methanol conversion, p‐benzoquinone had little effect and p‐cresol caused an increase in methanol conversion.

Magic-angle-spinning NMR

Magic-angle-spinning NMR is a very powerful technique which allows high-resolution spectra to be obtained from solids, even when the sample is microcrystalline or amorphous. The principles of the technique are described and examples given of its usefulness in many areas of chemistry with special stress being laid on aluminosilicate catalysts.

Preparation of a novel aluminosilicate catalyst from a microporous silica xerogel

A novel catalyst having a pore diameter of ca. 1.0 nm was prepared by depositing an aluminosilicate on the surface of a microporous silica xerogel. This catlyst has been designated TDZ-48. The negative charge carried by the constituent aluminium ions, which were in 4-co-ordination with oxygen, might have been balanced by aluminium hydroxide cations such as Al(OH) 2 +, and by protons. The resultant Brönsted acidity enabled almost complete conversion of methanol to be achieved over this catalyst at 400°C when the liquid hourly space velocity was 0.3 h −1.

Calorimetric measurements of adsorption power for active centers of aluminosilicate catalysts

Direct calorimetric measurements for the interaction energy of cumene and benzene with active centers of an aluminosilicate catalyst have been carried out to determine the potential energies of the centers catalyzing selective cracking with minimum coke formation. Kinetics of cumene cracking has been examined.

Isomerization of alkylaromatic hydrocarbons of aluminosilicate catalysts modified with composite compounds of nickel and copper: N. S. Kozlov, Ye. S. Osinovik, N. Ya. Pryakhina, G. M. Sen'kov and M. F. Gorbatse vich, Neftekhimiya 25, No. 2, 163–166, 1985

Isomerization of alkylaromatic hydrocarbons of aluminosilicate catalysts modified with composite compounds of nickel and copper: N. S. Kozlov, Ye. S. Osinovik, N. Ya. Pryakhina, G. M. Sen'kov and M. F. Gorbatse vich, Neftekhimiya 25, No. 2, 163–166, 1985

Cracking selectivity of a delaminated clay catalyst

Gas oil cracking selectivity is reported for a delaminated clay catalyst formed by the reaction of polyoxoaluminum cations with Laponite, a synthetic small particle hectorite. The C 5C 12 gasoline yields obtained with the delaminated clay more nearly approximate the selectivity of a commercial zeolite-promoted FCC catalyst than an amorphous aluminosilicate catalyst (AAA-alumina). In addition, the delaminated clay affords higher yields of light cycle gas oil and lower yields of slurry oil than the zeolite-promoted catalyst. This latter property is found also for clays which are pillared by polyoxoaluminum cations. The zeolite-like cracking properties and similarities to conventional pillared clays-suggest that some two-dimensional zeolitic character is retained by the delaminated clay, despite the absence of discrete 001 X-ray reflections and the presence of an appreciable macroporous component. The zeolite-like cracking selectivity, as well as the amorphous oxide-like macroporosity, is consistent with a previously proposed house-of-cards structure for the delaminated clay.

Treatment of wastewater from the production of aluminosilicate catalysts

One of the most widely used methods for wastewater treatment to remove coarsely dispersed and colloidal contaminants is treatment wlthcoagulants and flocculants. The most widely used coagulants are aluminum and iron salts, to a lesser extent magnesium, zinc, and titanium salts. The materials used as flocculants are water-soluble polyelectrolytes, in particular polyacrylamlde, VA-2, polyethyleneimine, etc.

The active site of acidic aluminosilicate catalysts

The availability of solid acidic catalysts based on zeolite ZSM-5 make possible observations on the nature and the absolute rate behaviour of the individual protonic sites. Tetrahedral aluminium atoms are the highly reactive ingredients, even at levels of parts per million, or less. Turnover numbers for several hydrocarbon reactions equal and exceed familiar enzymatic turnover values. Intensive catalytic activities can result from aluminium levels likely to be ignored by the experimenter.

Disposal and utilization of sludge from wastewater in production of aluminosilicate catalysts

Disposal and utilization of sludge from wastewater in production of aluminosilicate catalysts

Calorimetric studies of aluminosilicate catalysts. Heats and entropy of benzene adsorption on monosubstituted alkaline earth (Mg, Ca, Sr, Ba) metakaolinites at small surface coverages

Differential heats of benzene adsorption at 293 K on Mg2+, Ca2+, Sr2+, Ba2+ metakaolinites at surface coverages of θ=0.2 have been measured in a Calvet microcalorimeter. An inverse dependence of benzene and cuene adsorption heats on monocationic metakaolinites has been revealed. The presence of two types of adsorption centers is predicted.

Electronic spectra of azobenzene and p-dimethylaminoazobenzene adsorbed on surface of aluminosilicate catalysts and their quantum-mechanical interpretation

Electronic spectra of azobenzene and p-dimethylaminoazobenzene adsorbed on surface of aluminosilicate catalysts and their quantum-mechanical interpretation

Calorimetric studies of aluminosilicate catalysts heats and entropies of cumene adsorption on cation substituted metakaolinite

Differential heats of cumene adsorption at 293 K on Ca-, Sr- and Ba-substituted metakaolinites at surface coverages up to 0.1 have been measured on a Calvet microcalorimeter. The presence of two energetically different adsorption centers are shown to be determined by the nature of the exchanged cation; the adsorption heats decrease in the sequence Ba, Sr, Ca, Mg.

A Selective Pathway from Methanol to Ethylene and Propene

Assured supplies of raw materials is of topical interest in view of the threatening scarcity of petroleum. Mu‐doped aluminosilicate catalysts transform methanol into a surprisingly narrow range of products containing a large proportion of ethylene and propene. Methanol is accessible, in principle, from all carbonaceous materials via synthesis gas.

Hydrolysis of crystalline aluminosilicate catalysts. 27AI NMR of hydrated zeolite 13-x

NMR relaxation times, linewidths, and intensities for 27Al in Na X zeolite materials are compared for a hydrolyzed specimen and a specimen carefully protected against hydrolysis. The only parameter differing between the two materials is the relative intensity; only 75% of the aluminum nuclei in the hydrolyzed material are thus accounted for. In conjunction with older similar NMR data for protons and 23Na in these materials it is concluded that the “hydrolysis complex” is actually in the form Al(OH) a. The diffusion coefficient for this entity is estimated as D = 10 -8 exp( −3.08 RT ) cm 2sec -1 where R is in units kcal mol −1 deg −1. After completion of the paper D. H. Olson compared the hydrolyzed and normal zeolite specimens by electron probe microanalysis (specimens identical in Si/Al ratio), lattice parameter (hydrolyzed specimen 0.04 Å larger), atomic absorption spectroscopy (sodium concentrations not significantly different), and surface acidity (protons of the complex not acidic). As the amounts available for analysis were small (ca. 0.3 g), the replications necessary for good statistics in the sodium analysis could not be carried out. The result of the sodium analysis, while not confirming the model put forth in this paper (wherein sodium should be lost from the zeolite) is not taken as a completely trustworthy result because of this lack of replication. The NMR relative intensity measurements, nondestructive in character, were easily replicated in contrast.