Hydrodechlorination of 4-Chlorophenol on Pd-Fe Catalysts on Mesoporous ZrO2SiO2 Support

A mesoporous support based on silica and zirconia (ZS) was used to prepare monometallic 1 wt% Pd/ZS, 10 wt% Fe/ZS, and bimetallic FePd/ZS catalysts. The catalysts were characterized by TPR-H2, XRD, SEM-EDS, TEM, AAS, and DRIFT spectroscopy of adsorbed CO after H2 reduction in situ and tested in hydrodechlorination of environmental pollutant 4-chlorophelol in aqueous solution at 30 °C. The bimetallic catalyst demonstrated an excellent activity, selectivity to phenol and stability in 10 consecutive runs. FePd/ZS has exceptional reducibility due to the high dispersion of palladium and strong interaction between FeOx and palladium, confirmed by TPR-H2, DRIFT spectroscopy, XRD, and TEM. Its reduction occurs during short-time treatment with hydrogen in an aqueous solution at RT. The Pd/ZS was more resistant to reduction but can be activated by aqueous phenol solution and H2. The study by DRIFT spectroscopy of CO adsorbed on Pd/ZS reduced in harsh (H2, 330 °C), medium (H2, 200 °C) and mild conditions (H2 + aqueous solution of phenol) helped to identify the reasons of the reducing action of phenol solution. It was found that phenol provided fast transformation of Pd+ to Pd0. Pd/ZS also can serve as an active and stable catalyst for 4-PhCl transformation to phenol after proper reduction

Evolution of the Reagent for Iodination and Iodonitration. Optimization of the Synthesis Conditions in the Framework of Green Chemistry

Показана эволюция реагента Тронова-Новикова, проанализированы результаты работы нашей группы под руководством профессора М. С. Юсубова за последние двадцать лет в области йодирования и йоднитрования. Показаны новые возможности твердофазного реагента на основе йода (йодида калия) и (или) нитратов. Изучены химические свойства твердофазных реагентов и оптимизированы условия проведения реакций, которые позволяют проводить целенаправленный синтез продуктов моно- или дийодирования, йоднитрования, нитрования и гетероциклизации. Показано, что при йодировании активированных и умеренно активированных ароматических субстратов и фенилацетилена в условиях «solvent-free » с более высокими выходами получены продукты, аналогичные продуктам в синтезе с использованием растворителя. Предложены возможные окислительно-восстановительные схемы образования промежуточных частиц дийодосеребра (I) нитрата и нитрилйодида в реакциях без растворителя. Полученные теоретические и экспериментальные данные подтверждают возможность распада нитрилйодида по гомо- и гетеролитическому пути в зависимости от природы субстрата не только в синтезе с участием растворителя, но и в условиях «solvent-free »The evolution of the Tronov-Novikov reagent is shown. Scientific investigations of our research group under the leading of professor M. S. Usubov in the field of iodination and iodonitration have been analyzed. New possibilities of a solid-phase reagent based on iodine (potassium iodide) and (or) nitrates are represented. We have studied chemical properties of the solid-phase reagents and optimized conditions of reactions, which allow prediction the synthesis of products of mono- or diiodination, iodonitration, nitration, and heterocyclization. It has been found that iodination of activated and mild activated aromatic substrates and phenylacetylene under solvent-free conditions results with products similar to those obtained in the presence of solvent. However, the solvent-free procedure offers significant advantages such as higher yields, short reaction times with mild reaction conditions. Possible redox schemes were proposed for the formation of potential intermediate particles diiodosilver(I) nitrate and nitrile iodide in solvent-free reactions. Obtained theoretical and experimental data confirm the possibility of the homo- and heterolytic pathways decomposition of nitrile iodide, depending on the nature of the substrate, in the synthesis with a solvent, as well as under “solvent-free” condition

Copper–Cerium–Tin Oxide Catalysts for Preferential Oxidation of CO in Hydrogen: Effects of Synthesis Method and Copper Content

Copper was incorporated into the Ce-Sn and comparative Ce-Zr oxide supports by one-pot precipitation in the presence of CTAB template and by the impregnation of templated Ce-Sn and Ce-Zr oxides. The synthesized Cu-Ce-Sn and Cu-Ce-Zr catalysts were tested in the continuous-flow preferential oxidation of CO in hydrogen excess. The one-pot synthesized tin- and zirconium-doped catalysts demonstrated better CO conversion and CO2 selectivity than their impregnated counterparts. For the tin-modified ternary system that showed the best catalytic performance, the copper content was further optimized. The structure, reducibility, surface chemical state and textural properties of the catalysts were analyzed by SEM-EDX, XRD, H2-TPR, Raman spectroscopy, XPS and TEM. The nonmonotonic changes in the specific surface area, Cu+/Cu2+ ratio and ratio of lattice and non-lattice oxygen with increasing the Cu content are discussed in terms of copper distribution in the catalysts. The influence of the interaction between copper oxide species and the cerium–tin/cerium–zirconium oxide support on the performance of the ternary catalysts was thoroughly analyzed and discussed

Non-Oxidative Propane Dehydrogenation on CrOx-ZrO2-SiO2 Catalyst Prepared by One-Pot Template-Assisted Method

A series of CrOx-ZrO2-SiO2 (CrZrSi) catalysts was prepared by a “one-pot” template-assisted evaporation-induced self-assembly process. The chromium content varied from 4 to 9 wt.% assuming Cr2O3 stoichiometry. The catalysts were characterized by XRD, SEM-EDX, temperature-programmed reduction (TPR-H2), Raman spectroscopy, and X-ray photoelectron spectroscopy. The catalysts were tested in non-oxidative propane dehydrogenation at 500–600 °C. The evolution of active sites under the reaction conditions was investigated by reductive treatment of the catalysts with H2. The catalyst with the lowest Cr loading initially contained amorphous Cr3+ and dispersed Cr6+ species. The latter reduced under reaction conditions forming Cr3+ oxide species with low activity in propane dehydrogenation. The catalysts with higher Cr loadings initially contained highly dispersed Cr3+ species stable under the reaction conditions and responsible for high catalyst activity. Silica acted both as a textural promoter that increased the specific surface area of the catalysts and as a stabilizer that inhibited crystallization of Cr2O3 and ZrO2 and provided the formation of coordinatively unsaturated Zr4+ centers. The optimal combination of Cr3+ species and coordinatively unsaturated Zr4+ centers was achieved in the catalyst with the highest Cr loading. This catalyst showed the highest efficiency