E. A. Paukshtis

Preparing and studying Pt/WO3/ZrO2 catalysts for the isomerization of n-heptane

The effect of the temperature of WO3/ZrO2 support calcination in the range of 700–1000°C on the phase composition, acid, and catalytic properties of Pt/WO3/ZrO2 catalysts is studied. Using ammonia TPD, it is found that calcination in the temperature range of 850–950°C results in the formation of strong acid sites that increase the yield of the target products of the reaction of n-heptane isomerization: high octane di- and trimethylsubstituted isomers. DRIFT is used to determine the role of catalyst calcination in an air flow plays in the formation of charged platinum atoms, which results in higher catalyst activity.

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.

Light olefins synthesis from C1-C2 paraffins via oxychlorination processes

A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCl10/TiO2 catalyst was tested for the oxidative chlorination of methane and ethane. The catalyst had high selectivity for methyl and ethyl chlorides, 80% and 90%, respectively. During the oxychlorination of ethane at T⩾250°C, the formation of ethylene as a reaction product along with ethyl chloride was observed. In situ Fourier transform infrared studies showed that the key intermediate for monoalkyl chloride and ethylene formation is the alkoxy group. The reaction mechanism for the oxidative chlorination of methane and ethane over the Ru-oxychloride catalyst was proposed. The novel fiber glass catalyst was also tested for the dehydrochlorination of alkyl chlorides to ethylene and propylene. Very high selectivities (up to 94%–98%) for ethylene and propylene formation as well as high stability were demonstrated.

Study of the factors affecting the formation of copper–chromium/aluminum oxide compounds with a spinel structure

The effect of the Cr3+/Al3+ ratio on the crystallization temperature of mixed oxide compounds with a spinel structure and their structural features and morphological characteristics have been studied using a combination of physicochemical methods: thermal analysis, IR spectroscopy, X-ray powder diffraction, and electron microscopy. The role of temperature of synthesis and drying of Cu–Cr/Al hydroxy precursors in the formation of copper-containing spinels CuCrxAl2–xO4, where x = 0–2, has been elucidated. The results are of interest for selection of the optimal composition and conditions of synthesis and formation of copper-containing spinels for their practical use.

Preparation and Characterization of Catalysts Pt/WO3/ZrO2 for Isomerization of n-Heptane

The influence of the calcining temperature of the support WO 3 /ZrO 2 at 700–1000 °C on the phase composition, acid and catalytic properties of catalysts Pt/WO 3 /ZrO 2 was studied. The method of ammonia TPD was used to establish that strong acid centers formed at the calcining temperature between 850 and 950 °C favor an increase in the yields of target products of n -heptane isomerization – high-octane di- and trimethyl substituted isomers. IRS-DR studies revealed the role of the catalyst calcining in flowing air that is to form charged platinum atoms which contribute to improvement of the catalyst activity.

Effect of the zeolite modulus of Pt/MOR/Al2O3 catalysts on the n-heptane isomerization reaction

The effect of the mordenite acidic modulus (SiO2/Al2O3, 20 and 30) of Pt/MOR/Al2O3 catalysts on the heptane isomerization reaction is investigated. The content of zeolite in the catalysts is varied from 10 to 50 wt %, with platinum applied to the samples from solutions of different precursors: H2PtCl6 and [Pt(NH3)4]Cl2. It is established via the TPD of ammonia and FTIR spectroscopy (the adsorption of NH3 and СО) that the total acidity of zeolite falls as the modulus grows: the number of Brønsted (BAC) and Lewis (LAC) acidic sites is reduced, accompanied by an increase in the strength of their acidity. The catalysts are tested in the n-heptane isomerization reaction. It is shown that the selectivity of n-heptane isomerization falls substantially when the acidic mordenite modulus is increased from 20 to 30.

Light olefins synthesis from C 1 -C 2 paraffins via oxychlorination processes

A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCl10/TiO2 catalyst was tested for the oxidative chlorination of methane and ethane. The catalyst had high selectivity for methyl and ethyl chlorides, 80% and 90%, respectively. During the oxychlorination of ethane at T⩾250°C, the formation of ethylene as a reaction product along with ethyl chloride was observed. In situ Fourier transform infrared studies showed that the key intermediate for monoalkyl chloride and ethylene formation is the alkoxy group. The reaction mechanism for the oxidative chlorination of methane and ethane over the Ru-oxychloride catalyst was proposed. The novel fiber glass catalyst was also tested for the dehydrochlorination of alkyl chlorides to ethylene and propylene. Very high selectivities (up to 94%–98%) for ethylene and propylene formation as well as high stability were demonstrated.

Light olefins synthesis from С1-С2 paraffins via oxychlorination processes

A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCl10/TiO2 catalyst was tested for the oxidative chlorination of methane and ethane. The catalyst had high selectivity for methyl and ethyl chlorides, 80% and 90%, respectively. During the oxychlorination of ethane at T⩾250°C, the formation of ethylene as a reaction product along with ethyl chloride was observed. In situ Fourier transform infrared studies showed that the key intermediate for monoalkyl chloride and ethylene formation is the alkoxy group. The reaction mechanism for the oxidative chlorination of methane and ethane over the Ru-oxychloride catalyst was proposed. The novel fiber glass catalyst was also tested for the dehydrochlorination of alkyl chlorides to ethylene and propylene. Very high selectivities (up to 94%–98%) for ethylene and propylene formation as well as high stability were demonstrated.