B. S. Bal’zhinimaev

The process for catalytic incineration of waste gas on IC-12-S102 platinum glass fiber catalyst

The process for catalytic afterburning of volatile organic compounds (VOCs) in waste industrial gases was developed on the basis of a new platinum glass fiber catalyst (GFC) IC-12-S102 with low platinum content (∼0.02 wt %). The catalyst was shown to be more effective than the known industrial afterburning catalysts. The way of glass fiber catalyst loading to a reactor in the form of vertical spiral cartridges, structured with wire mesh of bulk weaving is described. The successful application of the IC-12-S102 catalyst was confirmed by its operation at OAO Nizhnekamskneftekhim in the process of waste gases afterburning in an industrial reactor with cleaned gases capacity up to 15000 m3/h. During the reactor operation in harsh conditions (low oxygen content, high content of water vapor), the degree of gas cleaning was 99.5–99.9% and the residual VOC content in the purified gases was no higher than 10–15 mg/m3. For more than 15 months of catalyst operation, the degree of gas purification was not reduced; thus, overall lifetime of the IC-12-S102 catalyst may be substantially longer than the life of well-known industrial afterburning catalysts.

Phase transitions in a bed of vanadium catalyst for sulfuric acid production: experiment and modeling

Abstract Sulfur dioxide oxidation on vanadium catalysts in sulfuric acid production may cause phase transitions in the catalyst active component. These phase transitions involve crystallization of vanadium(IV), and may influence catalyst activity. In the present study, we show that reaction mixture flow through a fixed catalyst bed is accompanied by the moving front of crystal phase, which decreases SO 2 conversion at reactor outlet. Front profile and its movement velocity depend on the chemical composition of active component, support porous structure, catalyst particle size, and other parameters. Based on the Gibbs–Volmer theory, we suggest a simplified mathematical model, which (qualitatively and quantitatively) describes experimentally observed dynamics of front generation and movement, as well as related changes in the bed activity. The model allows us to predict catalyst behavior in an industrial scale reactor, and to optimize catalyst properties.

Copper catalysts based on fiberglass supports for hydrocarbon oxidation reactions with the participation of hydrogen peroxide

Copper-containing catalysts were prepared by the adsorption of the ammonia complexes of Cu(II) on the surface of a silicate fiberglass material followed by the thermal and oxidative treatment of the samples. The states of copper after the adsorption of ammonia complexes and in the prepared samples were characterized using electronic diffuse reflectance spectroscopy. The catalytic activity of the samples in hydrogen peroxide decomposition and cyclohexane oxidation reactions was studied. It was found that molecular oxygen can be involved in the radical process of hydrogen peroxide oxidation. Based on spectroscopic data, it was hypothesized that partially reduced Cu(I)–Cu(O) compounds are active species in the catalysts of this type.

Study of leaching of sodium aluminosilicate fiberglass materials

The effects of temperature, time, and the composition of the solvent (water, HCl) on the processes of leaching of Na, Al, and Ca from sodium aluminosilicate fiberglass materials and also the physicochemical properties of the leached products were studied by inductively coupled plasma atomic emission spectroscopy, differentiating dissolution, and IR spectroscopy. It was found that, in water and aqueous HCl solutions, the process is dominated by the extraction of sodium from the glass because of the ion exchange of Na+ for H+. The Na leaching rate in H2O is limited by the ion-exchange rate on the glass fiber surface, and that in HCl is controlled by the Na diffusion in the bulk of the glass fiber. The structure of the leached glass fibers is formed by alternate sheets of several silicon–oxygen tetrahedra separated by narrow voids, which contain a considerable amount of molecular water and SiOH groups, characterized by the band of stretching vibrations of OH (ν = 3640 cm–1). In annealing, SiOH groups condense to release water; however, the ion-exchange properties of the fibers are partially conserved.

Studying the role of the state of platinum in Pt/SO4/ZrO2/Al2O3 catalysts in the isomerization of n-hexane

Samples of SO4/ZrO2/Al2O3 and Pt/Al2O3 Pt/Al2O3 catalysts and their physical mixtures are prepared, and the catalytic properties of the samples in n-hexane isomerization are studied. The considerable effect of the state of platinum on the catalytic performance of the samples is revealed. IR spectroscopy (COads), oxygen chemisorption, and oxygen-hydrogen titration show that the reduced catalysts contain ionic forms of platinum capable of adsorbing up to three hydrogen atoms per each surface atom of platinum. By means of H/D isotopic exchange, it is found that specific properties of ionic platinum are apparent in the formation of the hydride form of adsorbed hydrogen. It is speculated that the activity and stability of catalysts based on sulfated zirconia in n-hexane isomerization can be attributed to the involvement of ionic and metallic platinum in the activation of hydrogen. The results can be used to develop effective catalysts for the isomerization of C5–C6 gasoline fractions in order to obtain the isomerizate as a high-octane additive for modern gasolines.

Silicate fiberglass catalysts: From science to technology

Efficient methods for the confining of highly dispersed Pd and Pt particles 1–1.5 nm in size in the subsurface layers of silicate glass fibers at depths of 10–20 nm are developed. Fiberglass catalysts reveal high activity in the selective hydrogenation of acetylene and the deep oxidation of hydrocarbons despite their low metal contents (0.01–0.02 wt %). The monometallic Pd/FG catalyst thus exhibits higher C2H2 hydrogenation selectivity at high acetylene conversion (99%+) in comparison to the commercial bimetallic Pd–Ag catalyst, and the activity of the Pt/FG catalyst in the deep oxidation of organic and chlororganic compounds, including dioxins, is found to be higher than that of the commercial AP-56 (Pt/Al2O3) catalyst. The efficiency of Pt/FG has successfully been demonstrated in the removal volatile organic compounds (VOC) from Monomer plant of PJSC Nizhnekamskneftekhim for more than four years of continuous operation.

Phase transitions in the active component of vanadium catalyst for sulfur dioxide oxidation: crystal phase dissolving

As sulfur dioxide is oxidized on vanadium catalysts, phase transitions may occur in the catalyst active component, which are related to the crystallization of vanadium(IV) compounds resulting in the decrease of catalyst activity. In this paper, we report on the peculiarities of reversal process such as crystal phase dissolving, which is aimed at catalyst regeneration. We have studied how crystal phase dissolving rate depends on dissolving conditions such as temperature, gas mixture composition as well as on the conditions of crystal phase formation. Dissolving dynamics is described by a mathematical model, which was earlier suggested for the processes of crystal phase generation and growth.