A. A. Lamberov

Catalytic dehydration of α-phenylethanol on the surface of aluminum oxides

The relationship between the acid–base properties of commercial and test samples of aluminum oxides and their catalytic activity in the dehydration of α-phenylethanol was studied. It was found that, in the dehydration of α-phenylethanol, the conversion of the alcohol and the yield of styrene on a catalyst depend on the concentrations of both Brønsted and Lewis acid sites. A hypothetical mechanism of the dehydration with the participation of coordinatively unsaturated aluminum atoms and bridging oxygen ions on the alumina surface was proposed.

Effect of Peptization on Texture and Physicomechanical Properties of Aluminum Hydroxides

The method of low-temperature adsorption of nitrogen was applied to study structural characteristics of commercial peptized aluminum hydroxides. An increase or decrease in the porometric volume, depending on the nature and concentration of the peptizing agent, was analyzed. The phenomena observed are explained in terms of the mechanism suggested for formation of the pore system in commercial aluminum hydroxides. The dependence of the physicomechanical properties of active aluminum oxide on synthesis conditions and texture characteristics of commercial aluminum hydroxides was studied.

Effect of Acid Modification on the Structure and Catalytic Activity of Aluminum Oxide

The effect of acetic acid introduced as modifying additive into active aluminum oxide on its structural characteristics is considered. A relationship is established between the structural characteristics, content and features of aprotic acid centers, and catalytic activity of the obtained catalysts in dehydration of methylphenylcarbinol.

Experience of the industrial use of alumina and KA zeolite in the processes of drying of olefin-containing mixtures in petrochemical industry

Problems arising in relation to the use of alumina and zeolite KA in the processes of drying olefin-containing streams in petrochemical production lines were analyzed, and the advantages offered by zeolites were shown. The reasons for the domination of imported zeolites on the domestic market are considered, and recommendations for strengthening the positions of national zeolite manufactures are given.

Development of technology for the production of microspherical aluminum oxide supporter for the paraffin dehydrogenation catalyst

For the purpose of improving the mechanical strength and to reduce the abrasive activity of microspherical chromoalumina catalyst for the paraffin dehydrogenation in fluidized bed, technology, using technical aluminum trihydrate as an initial raw material and including consecutive stages of Al(OH)3 dehydration and hydrothermal processing of its product into boehmite, has been developed for the production of highly durable boehmite supporter. As applied to the iso-butane dehydrogenation into iso-butylene, microspherical chromoalumina catalysts, which are synthesized with the use of boehmite supporter, exceed their known industrial analogous in activity, selectivity and physicomechanical properties. The technology of supporter and iso-butane dehydrogenation catalyst is realized at OAO Karpov Mendeleevsk Chemical Plant (Mendeleevsk) for the production with the capacity of 100 t per month. Industrial catalyst lots are under operation at the Synthetic Isoprene Rubber Plant of OAO Nizhnekamskneftechim. The given article consists of two parts. In the first one, investigation results are presented for the changes in technical properties of Al(OH)3 during its dehydration in an industrial continuous baking drum-type furnace. The changes in physicomechanical characteristics of granules at the dehydration stage are caused by phase transformations of gibbsite and boehmite, by crystalline structure rearrangements in the volume of microgranules and do not depend on mechanical loads in a baking furnace and on porous structure changes. The conditions of gibbsite complete phase change into the two-phase boehmite-χ-Al2O3 mixture with minimal reduction in the microgranules strength have been determined: Tav = 435−475°C, νTHA = 170 kg/h, and τav = 0.8 h.

Effect of the paste molding pressure on the mechanical strength of an iron oxide catalyst in the dehydrogenation of methylbutenes

The effect of the paste molding pressure on the physicomechanical and texture characteristics of catalysts was studied. An indirect criterion is suggested to evaluate the molding pressure in industrial extruders, whose optimal value ensures good physicomechanical properties of the catalysts and kinetic control over the catalyzed reaction. The results obtained were verified in paste molding on various industrial extruders, and this enabled the optimal choice of the molding equipment.

Effect of the paste molding pressure on the activity of iron oxide catalyst in dehydrogenation of methylbutenes

The effect of the paste molding pressure on the activity of an iron oxide catalyst in dehydrogenation of methylbutenes was studied. The study involved detailed analysis of the pore structure of the samples by mercury porosimetry and determination of the mode of the catalytic process (kinetic or diffusion control). The range of pore sizes in which dehydrogenation reactions occur was determined.

Effect of Deposition and Stabilization Conditions on the Texture Properties of Aluminum Hydroxides

Methods of low-temperature adsorption of nitrogen and X-ray phase analysis were applied to study structural characteristics of aluminum hydroxides synthesized under industrial conditions. A mechanism of formation of the porous structure of aluminum hydroxides was suggested.

Thermodynamic parameters of the single-stage dehydrogenation of isopentane to isoprene

From the results of experiments with platinum-containing catalysts operating in the steady mode, adiabatic changes in temperature in the course of 2-metylbutane dehydrogenation to monoolefins and isoprene were calculated. Dehydrogenation of 2-methylbutane and its mixtures with methylbutenes in the 500–600°C temperature range was simulated with varying the concentrations of 2-methylbutane, methylbutenes, hydrogen, and water, the conversion, and the selectivities with respect to both isoprene and methylbutenes. The most suitable reactor designs with intermediate heating of the reaction mixture were suggested.

Dehydration of Methyl Phenyl Carbinol Catalyzed by Modified Active Aluminum Oxide

The effect of modification with metal salts and acids on the acid-base characteristics and the catalytic properties of active aluminum oxide in the reaction of methyl phenyl carbinol dehydration to styrene was studied using the IR spectroscopy of adsorbed base molecules. The surface treatment of γ-Al2O3 with chromium and nickel cations decreased the catalyst activity because of the occurrence of hydrogenation side reactions. The appearance of strong Bronsted and Lewis acid sites as a result of modification with sulfate, nitrate, and fluoride anions accelerated the deactivation of the catalyst. Upon modification with acetic acid solutions, additional Lewis acid sites with QCO = 33.5−34 kJ/mol were formed on the surface of aluminum oxide, and the concentration of strong basic sites with PA = 900 kJ/mol decreased; this facilitated an increase in the catalyst activity and a decrease in the rate of catalyst deactivation.