EFFECT OF THE ORDER OF APPLICATION OF COPPER AND ZINC COMPOUNDS ON CATALYTIC ACTIVITY IN CO-OXIDATION REACTION

На основе алюмохромового носителя экстракционно-пиролитическим методом (ЭПМ) синтезирована серия медь-цинк-содержащих катализаторов, проанализировано влияние порядка внесения активных компонентов (меди и цинка) на качественный и количественный состав формирующихся фаз, а также глубину размещения в гранулах носителя, структурно-прочностные и каталитические свойства образцов в процессе окисления СО кислородом воздуха.Рассчитанные значения энергии активации и предэкспоненциального множителя показали, что порядок внесения активных компонентов оказывает влияние на кинетические параметры: наилучшие результаты наблюдаются в образцах, полученных совместной пропиткой алюмохромового носителя. Константы скорости реакции окисления СО (k), рассчитанные во всем температурном диапазоне более, чем в 2 раза выше, чем при совместном внесении компонентов.С помощью электронно-зондового микроанализа изучена текстура поверхности катализаторов ЭПМ, установлено, что не смотря на порядок внесения, технология ЭПМ позволяет получать однородную текстуру - поверхность катализаторов характеризуется слоистостью с частицами чешуйчатой структуры с минимальным размером частиц во всех случаях 0,4 мкм, максимальным 3-4 мкм. Совместное внесение Zn и Cu обеспечивает равномерное распределение компонентов по сечению гранул катализаторов.Результаты работы могут быть применимы для построения технологии эффективных медь-цинковых катализаторов для процессов окисления. Область применения катализаторов – комплексная очистка многокомпонентных газовых смесей. A series of copper-zinc-containing catalysts was synthesized on the aluminum - chromium oxides base by the extraction -pyrolytic method (EPM), the effect of the order application active components (copper and zinc) on the qualitative and quantitative composition of the formed phases, as well as the depth of placement in the granules of the baser, structural strength and catalytic properties of samples during oxidation with air oxygen was analyzed.The calculated values of the activation energy and the pre-exponential multiplier showed that the order of application active components has an effect on the kinetic parameters: the best results are observed in samples obtained by joint impregnation of an alumochrome carrier. The rate constants oxidation CO (k) calculated over the entire temperature range are more than 2 times higher when the components added together.Using electron probe microanalysis, the surface texture of the EPM catalysts was studied, it was found that, despite the order of application, the EPM technology allows to obtain a homogeneous texture - the surface of the catalysts is characterized by layering with particles of a scaly structure with a minimum particle size of 0.4 microns in all cases, and maximum 3-4 microns. The joint application of Zn and Cu ensures an even distribution of the components over the cross section of the catalyst granules.The results of the work can be applied to build a technology of effective copper-zinc catalysts for oxidation processes. The scope of application of catalysts is complex purification of multicomponent gas mixtures.

Making sense of gas measurements: quantification of multicomponent gas mixtures in biological and chemical laboratory experiments

Textbooks in physical chemistry start from the treatise of the ideal gas. Gaseous compounds are important reactants and products of (bio)chemical reactions, and thus their absolute amounts are needed to establish mass balances. However, in contrast to solid, for dissolved and liquid compounds, their qualitative and especially quantitative analysis is less widely established in biological and chemical laboratories. This can be mainly ascribed to the seemingly simple chemical nature of gaseous compounds that is in contrast to the effort needed for their precise quantification. In this article, we will guide the reader through the considerations and steps needed to perform a meaningful analysis of multicomponent gas mixtures, which are reactants for or products of (bio)chemical reactions in aqueous solutions in the laboratory environment and scale. After a brief introduction, special focus is set on the methods for quantification and calculations needed to derive absolute amounts of gases in a mixture. The overall concept will be exemplified by biogas production as well as by an electroorganic reaction (Kolbe electrolysis of n-hexanoic acid), and general pitfalls will be highlighted.

Collisions of Liquid Droplets in a Gaseous Medium under Conditions of Intense Phase Transformations: Review

The article presents the results of theoretical and experimental studies of coalescence, disruption, and fragmentation of liquid droplets in multiphase and multicomponent gas-vapor-droplet media. Highly promising approaches are considered to studying the interaction of liquid droplets in gaseous media with different compositions and parameters. A comparative analysis of promising technologies is carried out for the primary and secondary atomization of liquid droplets using schemes of their collision with each other. The influence of a range of factors and parameters on the collision processes of drops is analyzed, in particular, viscosity, density, surface, and interfacial tension of a liquid, trajectories of droplets in a gaseous medium, droplet velocities and sizes. The processes involved in the interaction of dissimilar droplets with a variable component composition and temperature are described. Fundamental differences are shown in the number and size of droplets formed due to binary collisions and collisions between droplets and particles at different Weber numbers. The conditions are analyzed for the several-fold increase in the number of droplets in the air flow due to their collisions in the disruption mode. A technique is described for generalizing and presenting the research findings on the interaction of drops in the form of theoretical collision regime maps using various approaches.