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The present work aimed to prepare Ni-Mo particles distributed within the MgO matrix. With this purpose in mind, a ternary Ni-Mo-Mg oxide system was synthesized by a sol−gel approach. The samples were studied by low-temperature nitrogen adsorption, X-ray diffraction analysis, and transmission electron microscopy equipped with energy dispersive X-ray analysis. Both the nickel and molybdenum species in the prepared samples were characterized by a fine and uniform distribution. The diffraction pattern of the ternary system was predominantly represented by the MgO reflections. The catalytic activity of the samples was tested in the decomposition of 1,2-dichloroethane used as a representative of the chlorinated organic wastes. The nanostructured carbon filaments resulting from the decomposition of the halogenated substrate were found to be characterized by a narrow diameter distribution, according to the transmission electron microscopy data, thus confirming the fine distribution of the active Ni-Mo particles. The results obviously show the advantages of the sol−gel technique for obtaining efficient catalysts.

In the present work, a series of two-component Ni-Mg-O oxide systems were prepared using a sol–gel technique at varied pH of hydrolysis procedure. The aqueous solutions of nitric acid or ammonia were added to control the pH values. The xerogel samples obtained after drying were analysed using a thermogravimetric approach. The oxide systems were characterized by a set of physicochemical methods (low-temperature nitrogen adsorption, X-ray diffraction analysis, scanning electron microscopy, UV-vis spectroscopy, and temperature-programmed reduction method). The thermal stability of the samples was examined in a testing reaction of CO oxidation in a prompt thermal aging regime. It was revealed that the pH value during the magnesium methoxide hydrolysis stage significantly affects the properties of the intermediate hydroxide and final oxide nanomaterials. The thermal decomposition of nitric acid or ammonia is accompanied by exothermal effects, which noticeably influence the textural characteristics. Moreover, the pH of the hydrolysing solution defines the strength of the nickel interaction with the MgO matrix. An increase in pH facilitates the formation of the NixMg1−xO solid solution with a higher amount of incorporated nickel, which is characterized by the reproducible broad temperature range of the hydrogen uptake and the enhanced thermal stability.

A sol-gel technique was applied to prepare the two-component oxide system Cu-Mg-O, where MgO plays the role of oxide matrix, and CuO is an active chemical looping component. The prepared samples were characterized by scanning electron microscopy, low-temperature nitrogen adsorption, and X-ray diffraction analysis. The reduction behavior of the Cu-Mg-O system was examined in nine consecutive reduction/oxidation cycles. The presence of the MgO matrix was shown to affect the ability of CuO towards reduction and re-oxidation significantly. During the first reduction/oxidation cycle, the main characteristics of the oxide system (particle size, crystallization degree, etc.) undergo noticeable changes. Starting from the third cycle, the system exhibits a stable operation, providing the uptake of similar hydrogen amounts within the same temperature range. Based on the obtained results, the two-component Cu-Mg-O system can be considered as a prospective chemical looping agent.

Pd/Al2O3 catalyst of the “crust” type with Pd loading of 0.03 wt.% was prepared by the deposition of 2 nm Pd particles on the outer surface of the alumina support using laser electrodispersion (LED). This technique differs from a standard laser ablation into a liquid in that the formation of monodisperse nanoparticles occurs in the laser torch plasma in a vacuum. As is found, the LED-prepared catalyst surpasses Pd-containing three-way catalysts, obtained by conventional chemical synthesis, in activity and stability in CO oxidation under prompt thermal aging conditions. Thus, the LED-prepared Pd/Al2O3 catalyst showed the best thermal stability up to 1000 °C. The present research is focused on the study of the high-temperature evolution of the Pd/Al2O3 catalyst in two reaction mixtures by a set of physicochemical methods (transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance UV-vis spectroscopy). In order to follow the dispersion of the Pd nanoparticles during the thermal aging procedure, the testing reaction of ethane hydrogenolysis was also applied. The possible reasons for the high stability of LED-prepared catalysts are suggested.

The unique physical and chemical properties of composite materials based on carbon nanofibers (CNFs) makes them attractive to scientists and manufacturers. One promising method to produce CNFs is catalytic chemical vapor deposition (CCVD). In the present work, a method based on carbon erosion (CE) of bulk microdispersed Ni-Cu alloys has been proposed to prepare efficient catalysts for the synthesis of CNF-based composites. The initial Ni-Cu alloys were obtained by mechanochemical alloying (MCA) of metallic powders in a planetary mill. The effect of MCA duration on the phase composition of Ni-Cu samples was studied by X-ray diffraction analysis and temperature-programmed reduction in hydrogen. It has been also revealed that, during such stages as heating, reduction, and short-term exposure to the reaction mixture (C2H4/H2/Ar) at 550 °C, the formation of a Ni-based solid solution from the initial Ni-Cu alloys takes place. The early stages of the CE process were monitored by transmission electron microscopy combined with energy-dispersive X-Ray analysis. It was found that the composition of the catalytic particles is identical to that of the initial alloy. The morphological and structural features of the prepared Ni-Cu-CNF composites were studied by scanning and transmission electron microscopies. The textural characteristics of the composites were found to be dependent on the reaction time.

The present paper continues the exploration of the physicochemical and catalytic properties of vanadia-mayenite composites. The samples were prepared by an impregnation of calcium aluminate Ca12Al14O33 (mayenite, C12A7) with a solution of vanadium precursor. Pure mayenite and V/C12A7 nanocomposites were characterized by Raman and diffuse reflectance UV–Vis spectroscopies. The reducibility of the samples was examined in temperature-programmed reduction experiments performed in a hydrogen atmosphere. The catalytic performance of vanadium-containing systems was studied in the non-oxidative dehydrogenation of ethane. As found, the low-loaded sample (5%V/C12A7 sample) contains vanadium predominantly in the form of Ca3(VO4)2, while for the 10%V/C12A7 sample, two types of calcium vanadates (Ca2V2O7 and Ca3(VO4)2) are registered. The presence of these phases defines the spectroscopic characteristics and the redox properties of nanocomposites. Both the samples, 5%V/C12A7 and 10%V/C12A7, exhibit comparable catalytic activity, which is mainly connected with the amount of the Ca3(VO4)2 phase. The uniqueness of the studied catalysts is their excellent tolerance toward coke formation under the reaction conditions.