Influence of Thermal Activation of Titania on Photoreactivity of Pt/TiO2 in Hydrogen Production

A series of Pt/TiO2 photocatalysts was prepared by impregnation of fresh and thermal-activated titania (commercial Evonik Aeroxide P25 TiO2) with an aqueous solution of H2PtCl6 followed by reduction in an aqueous solution of NaBH4. The thermal activation was performed by annealing in air. The photocatalytic activity of the Pt/TiO2 catalysts was measured for the hydrogen production from a mixture of glycerol under UV radiation. It was found that the activation at 300–600 °C provides an increase in the photoreactivity of resulting Pt/TiO2 photocatalysts in the production of hydrogen while its structural and textural properties do not change. This effect is due to formation of cationic vacancies that limits fast electron–hole recombination

Expanded Brain CT Dataset for the Development of AI Systems for Intracranial Hemorrhage Detection and Classification

Intracranial hemorrhage (ICH) is a dangerous life-threatening condition leading to disability. Timely and high-quality diagnosis plays a huge role in the course and outcome of this disease. The gold standard in determining ICH is computed tomography. This method requires a prompt involvement of highly qualified personnel, which is not always possible, for example, in case of a staff shortage or increased workload. In such a situation, every minute counts, and time can be lost. The solution to this problem seems to be a set of diagnostic decisions, including the use of artificial intelligence, which will help to identify patients with ICH in a timely manner and provide prompt and quality medical care. However, the main obstacle to the development of artificial intelligence is a lack of high-quality datasets for training and testing. In this paper, we present a dataset including 800 brain CT scans consisting of multiple series of DICOM images with and without signs of ICH, enriched with clinical and technical parameters, as well as the methodology of its generation utilizing natural language processing tools. The dataset is publicly available, which contributes to increased competition in the development of artificial intelligence systems and their advancement and quality improvement

Atomic Structure of Pd-, Pt-, and PdPt-Based Catalysts of Total Oxidation of Methane: In Situ EXAFS Study

In this study, 3%Pd/Al2O3, 3%Pt/Al2O3 and bimetallic (1%Pd + 2%Pt)/Al2O3 catalysts were examined in the total oxidation of methane in a temperature range of 150–400 °C. The evolution of the active component under the reaction conditions was studied by transmission electron microscopy and in situ extended X-ray absorption fine structure (EXAFS) spectroscopy. It was found that the platinum and bimetallic palladium-platinum catalysts are more stable against sintering than the palladium catalysts. For all the catalysts, the active component forms a “core-shell” structure in which the metallic core is covered by an oxide shell. The “core-shell” structure for the platinum and bimetallic palladium-platinum catalysts is stable in the temperature range of 150–400 °C. However, in the case of the palladium catalysts the metallic core undergoes the reversible oxidation at temperatures above 300 °C and reduced to the metallic state with the decrease in the reaction temperature. The scheme of the active component evolution during the oxidation of methane is proposed and discussed

The Catalytic Performance of CO Oxidation over MnOx-ZrO₂ Catalysts: The Role of Synthetic Routes

MnOx-ZrO2 catalysts prepared by co-precipitation and vacuum impregnation were calcined at 400–800 °C and characterized by powder X-ray diffraction, textural studies, high-resolution transmission electron microscopy, temperature-programmed reduction, X-ray absorption near edge structure, and X-ray photoelectron spectroscopy. The catalytic activity was tested in the CO oxidation reaction. The activity of the co-precipitated samples exceeds that of the catalysts prepared by vacuum impregnation. The characterization studies showed that the nature of the active component for the catalysts obtained by co-precipitation differs from that of the catalysts obtained by impregnation. In the impregnation series, the most active catalyst was obtained at a temperature of 400 °C; its increased activity is due to the formation of MnO2 oxide nanoparticles containing Mn4+ and low-temperature reducibility. An increase in the synthesis temperature leads to the formation of less active Mn2O3, catalyst sintering, and, accordingly, deterioration of the catalytic properties. In the case of co-precipitation, the most active CO oxidation catalysts are formed by calcination at 650–700 °C in air. In this temperature interval, on the one hand, a MnyZr1−yO2−x solid solution is formed, and on the other hand, a partial separation of mixed oxide begins with the formation of highly dispersed and active MnOx. A further increase in temperature to 800 °C leads to complete decomposition of the solid solution, the release of manganese cations into Mn3O4, and a drop in catalytic activity

In Situ Study of Reduction of Mnx_xCo3–x_{3–x}O4_4 Mixed Oxides: The Role of Manganese Content

A series of Mn–Co mixed oxides with a gradual variation of the Mn/Co molar ratio were prepared by coprecipitation of cobalt and manganese nitrates. The structure, chemistry, and reducibility of the oxides were studied by X-ray diffraction (XRD), X-ray absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR). It was found that at concentrations of Mn below 37 atom %, a solid solution with a cubic spinel structure is formed. At concentrations above 63 atom %, a solid solution is formed on the basis of a tetragonal spinel, while at concentrations in a range of 37–63 atom %, a two-phase system, which contains tetragonal and cubic oxides, is formed. To elucidate the reduction route of mixed oxides, two approaches were used. The first was based on a gradual change in the chemical composition of Mn–Co oxides, illustrating slow changes in the TPR profiles. The second approach consisted in a combination of in situ XRD and pseudo-in situ XPS techniques, which made it possible to directly determine the structure and chemistry of the oxides under reductive conditions. It was shown that the reduction of Mn–Co mixed oxides proceeds via two stages. During the first stage, (Mn, Co)$_3$O$_4$ is reduced to (Mn, Co)O. During the second stage, the solid solution (Mn, Co)O is transformed into metallic cobalt and MnO. The introduction of manganese cations into the structure of cobalt oxide leads to a decrease in the rate of both reduction stages. However, the influence of additional cations on the second reduction stage is more noticeable. This is due to crystallographic peculiarities of the compounds: the conversion from the initial oxide (Mn, Co)$_3$O$_4$ into the intermediate oxide (Mn, Co)O requires only a small displacement of cations, whereas the formation of metallic cobalt from (Mn, Co)O requires a rearrangement of the entire structure

Effect of Temperature on the Hydrotreatment of Sewage Sludge-Derived Pyrolysis Oil and Behavior of Ni-Based Catalyst

The high-energy potential of wastewater sewage sludge (SS) produced in large amounts around the world makes it an attractive feedstock for fuels and energy sectors. Thermochemical valorization relying on pyrolysis of SS followed by hydrotreatment of pyrolysis oil (Py-SS) might even allow the integration of SS into existing oil refineries. In the present study, catalytic hydrotreatment of Py-SS was performed over a NiCuMo-P-SiO2 catalyst in a batch reactor at temperatures in the range of 200–390 °C. Due to sulfur presence in the feed, the increasing reaction temperature induced in situ transformation of metallic Ni into Ni3S2 in the catalyst. In contrast, the Ni3P active phase possessed remarkable stability even at the harshest reaction conditions. The oxygen content in the reaction products was decreased by 59%, while up to 52% of N and 89% of S were removed at 390 °C. The content of free fatty acids was greatly reduced by their conversion to n-alkanes, while the larger amount of volatile aromatics was generated from high molecular mass compounds. The quality of oil-derived products greatly changed at elevated temperatures, providing strong evidence of effective upgrading via decarboxy(ny)lation, hydrogenation, and hydrocracking transformations