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Growing hydrogen demand and progress in fuel cell technology contributed to renewed interest in water-gas shift (WGS) reaction. Supported gold catalysts attracted a special attention during the last three decades. Given the undisputed role of support nature in catalyst activity the purpose of this work was exploration of the effect of ceria amount (1, 3, and 5 wt%) and preparation approach as sol-gel (SG) or mechanochemical mixing (MM) to WGS activity of Au/TiO 2 catalyst. Thorough studies using textural measurements, X-ray fluorescence spectrometry, powder X-ray diffraction, transmission electron microscopy, UV–Vis diffuse reflectance, UV-Raman and X-ray photoelectron spectroscopy, electron paramagnetic resonance, and temperature-programmed reduction were carried out to explain the relationship among structure, electronic properties, and WGS performance. The catalysts showed a notably better performance as compared to Ce-free Au/TiO 2 counterpart by reaching a 90−93 % CO conversion at 180 °C vs. 75 % with unmodified sample. Formation of defective Ti 4 O 7 and Ce 11 O 20 phases occurred during sample preparation by SG. In addition, a distinct ceria phase was found in MM-prepared carriers to assist preferential gold deposition. All these structures contributed to improved WGS activity of the supported gold catalysts. Activity enhancement was related to Ce–Ti interactions and modification of structural and electronic properties that favor water dissociation. New insights into structure-to-function relationships of Au/Ce–TiO 2 catalysts for WGS reaction are provided. [Display omitted] • Effect of Ce doping in Au/TiO 2 and preparation route on WGS activity was explored. • Au/Ce-doped TiO 2 outperformed Au/TiO 2 by reaching a 93 % CO conversion at 180 °C. • Defective Ti 4 O 7 and Ce 11 O 20 phases occurred during sample preparation. • Modification of structural and electronic properties favored H 2 O dissociation. • Tuning physicochemical properties of TiO 2 enable higher WGS activity of Au catalysts. [ABSTRACT FROM AUTHOR]

• Synergistic effect between components is found in most active KCoRe catalyst. • The Re4+/Re7+ ratio gives information about sour WGS activity of rhenium catalysts. • A balance between Re4+ sulphide and Re7+ oxide structures is found in KCoRe catalyst. • The KCoRe system is considered a promising sour WGS catalyst in the 250–400 °C range. Series of Re 2 O 7 /γ-Al 2 O 3 catalysts promoted with Ni, Co, and K were studied as sour gas shift catalysts. Samples were prepared by consecutive incipient wetness impregnation. Catalytic measurements were performed in a fixed bed reactor at atmospheric pressure in the range of 180–400 °C at GHSV of 4000 h−1 and steam/gas ratio of 0.3. The samples were characterised by means of N 2 physisorption, X-ray diffraction, diffuse reflectance UV–vis spectroscopy, and X-ray photoelectron spectroscopy. It was found that oxidation state ratio of rhenium sulphidic to rhenium oxygen-containing species, namely Re4+/(Re7+(+Re6+)), gives important information about redox relationship between Re4+ and Re7+ oxidation states according to additive type (K, Ni, and Co) and combinations among them. Three factors, namely, uniform deposition of K-Co-Re species on carrier surface, balance between Re sulphidic and oxidic species, and synergism among components were beneficial to the highest activity of KCoRe catalyst. This system was considered a promising catalyst for water-gas shift reaction with sulphur-containing feed in the 250–400 °C temperature range. [ABSTRACT FROM AUTHOR]

Highlights: [•] The components do not strongly change the primary mesoporous texture of γ-Al2O3. [•] The nature and bond strength of the oxide precursors generate different S species. [•] Both tungsten reducibility and sulphur stability to oxidation determine the activity. [•] The KNiW system exhibits both features to moderate extent and the highest activity. [ABSTRACT FROM AUTHOR]

Abstract: One-component samples containing K, Ni, and various concentrations of Mo were prepared by incipient wetness impregnation technique. Bi- and tri- component samples have been prepared from the calcined one- and bi-component samples following the same procedure. The samples were characterized by SSA, FT-IR, DRS and Raman measurements. The decrease of the ratio Ni2+(Td)/Ni2+(Oh) with the increase of Mo loading and the re-dispersion of Mo phase after the Ni addition on the one-component Mo containing samples proved the occurrence of interactions between these components in the bi-component NiMo-containing samples. Most probably Ni–Mo–O surface species with different number of Mo-oxo and Ni-oxo entities are formed, depending on the Ni/Mo atomic ratio. It may be accepted, that the Ni2+ ions are partially localized into the molybdate layer without forming well-defined phases. Two kinds of K+ ions have been determined in the corresponding samples, interacting (“bounded” K+ ions) and not interacting (“free” K+ ions) with the rest of the supported phases. The potassium deposition increased the dispersion of Mo phase and influenced the coordination state of the Mo6+ and Ni2+ ions in the bi-component KMo-, KNi-containing samples and the tri-component KNiMo-containing samples. It provoked partial transformation of the polymeric Mo6+(Oh) species into monomeric Mo6+(Td) ones and Ni2+(Td) species predomination over Ni2+(Oh) ones. Most probably, new complex K–Ni–Mo–O species were formed on the support surface in the case of the tri-component samples. [Copyright &y& Elsevier]

Abstract: The changes in the corrosion characteristics of stainless steel OC4004 in 0.1M HNO3 after electrodeposition of thin Al and Ce oxide films on it has been investigated. The Ce2O3–CeO2 layers have been found to possess a pronounced stabilizing effect on the steel passive state and on its corrosion resistance, respectively, whereas the Al2O3 layers do not improve considerably the corrosion behaviour of the SS/Al2O3 system. A twice-lower corrosion current was observed with a ternary SS/Al2O3/Ce2O3–CeO2 system in the passive region, while the zones of potentials, where the steel is in a stable passive state, are not changed. The obtained results permit the assumption that the cerium oxides layer acts as an effective cathode playing a determining role with respect to the improvement of the corrosion behavior of the steel. It has been concluded that when the SS/Al2O3/Ce2O3–CeO2 system is used in media containing nitric acid, the corrosion will proceed at potentials where the passive state of steel would not be disturbed. [Copyright &y& Elsevier]

Abstract: Investigations have been carried out on the changes in the corrosion behaviour of OC4004 stainless steel protected by an electrochemically deposited Ce2O3–CeO2 film. It may be assumed, on the basis of the obtained results, that in addition to exercising a screening effect, the cerium oxides film plays the role of an effective cathode stabilizing the steel passive state, i.e. its corrosion resistance without changing the zones of potentials where the steel is in a stable passive state. It has been concluded that in the cases when the Ce2O3–CeO2-protected stainless steel will be used as a construction material for catalytic converters designed for purification of nitric acid containing emissions, the corrosion will proceed at potentials, where the steel passive state will not be disturbed. Simultaneously, the presence of the Ce2O3–CeO2 coverage screens the accumulation on the SS/Ce2O3–CeO2 surface of iron/iron oxides and hydroxides, which could have a negative effect (as catalyst poisons), on the desired catalytic process. [Copyright &y& Elsevier]

Abstract: The one-, bi- and tri-component (K)(Ni)(Mo)/γ-Al2O3 systems are studied after water–gas shift reaction tests in the presence of sulfur in the feed. The samples are characterized after the calcination procedure (oxidic state) and after the catalytic activity test (tested state) by SSA, XRD, XPS and EPR measurements. The Mo4+, Mo5+ and Mo6+ oxidation states are registered on the surface of the tested samples. The different sulfur species such as: sulfide sulfur, oxysulfides, polysulfides, paramagnetic sulfur and sulfate sulfur are present on the sample surface in the reaction redox environment (CO, H2O, H2S, H2 and CO2 agents). The XPS and EPR characterization of the tested state points to the idea that both the molybdenum reducibility (i.e. the Mo4+/(Mo5+ +Mo6+) and Mo4+/Mo5+ ratios) and the sulfur lability (sulfide/sulfate ratio) represent informative indices in regard to the catalytic properties of the Mo-containing systems in the WGS reaction in case of sulfur presence in the feed mixture. [Copyright &y& Elsevier]

This work presents a new electrochemical method (i.e. new electrolyte composition and electrolysis regimes) for direct formation of Al2O3 on different metal substrates from non-aqueous electrolytes, data on the kinetics of the electrochemical processes and scanning electron microscopy (SEM) and XPS studies of the morphology, structure, dispersion and chemical composition of deposited Al2O3. [Copyright &y& Elsevier]

Sunflower oil hydrogenation process was studied on silica supported nickel catalysts. Three texturally different silica gel materials were used as supports for synthesis of Ni/Si02 catalyst precursors. After precursors' reduction and paraffin oil impregnation, obtained catalysts were used in sunflower oil hydrogenation reaction. For catalytic test, a new type of catalyst feeder was constructed and presented. The hydrogenation activity of catalysts was monitored through the decrease of refractive index and hydrogen consumption. A correlation between iodine value, refractive index and hydrogen consumption was established. The reaction rate constants were obtained from fatty acid composition of partially hydrogenated oil and further studied for the investigation of possible reaction pathways. Kinetics and mechanisms were evaluated and tested with the aim to reduce the number of reactions participating in the reaction scheme. A set of ordinary differential equations, corresponding to the investigated model, was solved numerically by Gear' s algorithm. It was shown that a number of significant reactions in a model depend on the activity of catalysts. More active catalyst results in more reaction pathways and more side chemical reactions. [ABSTRACT FROM AUTHOR]