In this paper, the preparation of calcium oxide (CaO) nanoparticles (NPs) is reported by a precipitation method, using CaCl2 and NaOH as starting raw materials. The produced NPs were characterized for chemical composition, phase composition, particle size distribution, morphological features, specific surface area, and crystallite sizes. It is shown that calcination of Ca(OH)2 in vacuum takes place faster/at a lower temperature compared to the calcination in air due to the higher entropy of the gaseous product of calcination. It is also shown that when these CaO nanoparticles are kept at room temperature in air, they fully and spontaneously transform into CaCO3 within 3 weeks. Therefore, if this material is disposed in open fields (not necessarily in industrial conditions), it is able to capture carbon dioxide from normal air slowly, but surely. However, when the CaO nanoparticles are kept in the air at 100–200 °C, they mostly capture water vapor from the air instead of carbon dioxide, and the resulting calcium hydroxide blocks the carbon dioxide capture by CaO nanoparticles.

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Carbon black (CB) supported palladium–platinum catalysts were prepared with and without nickel(II) oxide or iron(III) oxide promoter materials. By applying ultrasonic cavitation highly efficient CB supported catalysts were created. The designed catalyst preparation is a one-step procedure, as post-treatments (e.g. calcination, hydrogen activation) are not necessary. The activation of the catalysts occurs during their preparation due to the ultrasonic cavitation. Thus, a fast and simple catalyst preparation procedure have been developed. The activity of the catalysts was compared in nitrobenzene hydrogenation at different temperatures in the range of 283–323 K at 20 bar hydrogen pressure. In terms of selectivity and aniline yield, no significant differences were detected even when promoters were present. By using the NiO promoter, the activation energy was extremely low (7.6 ± 0.7 kJ mol−1). The selectivity was over 99% in every case, and 99.6% aniline yield was achieved without any promoters (99.7% with NiO), while less than 1.0% by-products were formed. The reaction rate was high with every catalyst, and no significant differences were detected. All in all, the prepared catalysts show excellent catalytic activity in the hydrogenation of nitrobenzene.

The aim of the present manuscript is to reveal the role of variant selection associated with the γ → ε and γ → ε → α′ transformations in the resulting texture of γ, ε and α′ phases of FeMnCr steels during uniaxial loading. Tensile tests were carried out at temperatures well above and close to the martensite start temperature of the ε phase ($$ M_{\text{s}}^{\varepsilon } $$Msε). Pole figures were obtained from the cross-section of the fractured specimens by X-ray diffraction (XRD). The γ 〈111〉 texture developed regardless of test temperature. It was found that the ratio of diffracted intensity in the 0 and ~ 70 deg directions with respect to tensile axis notably changed with test temperature. The difference was caused by variant selection accompanying the γ → α′ transformation. At high temperatures, α′ martensite formed only in the ~ 70 deg directions, where the mechanical driving force is large. At lower temperatures, however, α′ martensite formed in the ~ 70 and 0 deg directions as well. It is also shown that stress/strain-induced ε martensite can only form in the ~ 70 deg directions. The results apply for all three examined steels.