The development of efficient gas diffusion electrodes (GDEs) using low-cost materials is an important task to increase the commercial attractiveness of metal–air batteries. The use of carbon materials such as commercial grade activated carbons, laboratory carbon activated with sodium hydroxide, and laser-induced graphenes (LIG) in the active layer of GDE has been investigated. It has been shown that the efficiency of GDE in alkaline electrolyte correlates with the total surface area of micro- and mesopores of the used activated carbon. It has been established that small additions of LIG ( 5

In this paper, the features of the hydrothermal oxidation of dispersed aluminum are outlined and the prospects of its use for the mass production of “carbon-free” hydrogen are substantiated. In the course of hydrothermal oxidation, aluminum reacts with water or steam. In this case, hydrogen without the admixture of carbon or its compounds and thermal energy are formed. The solid product of aluminum oxidation is represented by aluminum hydroxide. This paper describes an integrated low-waste aluminum-water technology using such a single consumable agent as electricity. The technology involves the reduction to the metal of the obtained aluminum hydroxide within the framework of a single production. The aluminum regenerated in the electrolysis process can be again returned to the cycle for obtaining hydrogen from water in the hydrothermal oxidation reaction. If relatively recently developed inert anodes, as well as electricity generated at hydroelectric power plants or nuclear power plants, are used in the electrolysis of aluminum, then the technology has no carbon traces. The weight-energy characteristics and the composition of the products of each of the main processes used in the integrated aluminum-water technology are analyzed, namely the reduction of aluminum from Al 2 O 3 by means of electrolysis to return Al to the hydrogen-production cycle, the hydrothermal aluminum oxidation with the production of a steam-hydrogen mixture and a condensed mixture of water and boehmite, the obtaining of aluminum oxide Al 2 O 3 from boehmite AlOOH, obtaining pure hydrogen from a steam-hydrogen mixture as well as water for reuse, and hydrogen compression. Serious attention is paid to the potentialities of utilizing the thermal energy of the steam-hydrogen mixture for hydrogen compression. Owing to the production low-grade heat in large amounts under implementing the technology of hydrothermal aluminum oxidation, a thermal sorption compressor can be used for compressing hydrogen to operating parameters (40–90 MPa). This makes it possible to reduce the operating costs for hydrogen compression by more than an order of magnitude compared to traditional mechanical compressors and, at the same time, to provide an increase in the efficiency of aluminum hydrothermal oxidation.

A demo model of an automated hydrogen generator is described. The power-independent generator ensures the on-site hydrogen production on demand. Hydrogen evolution occurs when the hydrogen-generating formulation prepared by mechanochemical activation of aluminum reacts with water. Bismuth, tin (Bi 3.3 wt

The physicochemical and catalytic properties of 6%Ni/Al2O3 catalysts in the gas-phase hydrodechlorination of chlorobenzene (CB) are studied. The catalysts are synthesized by supporting nickel nitrate on two types of alumina—A (synthesized by aluminum isopropoxide hydrolysis) and E (manufactured by Engelhard)—with different morphologies and textures; some of the samples are unmodified, and some are modified by depositing 20% heteropoly acid (HPA) H8Si(W2O7)6 ⋅ nH2O. To prevent the HPA from decomposition, the air calcining and reduction of the modified materials are conducted at relatively low temperatures (250 and 330°C, respectively). To provide an adequate comparison, the catalysts containing no HPA are subjected to a similar treatment. Temperature-programmed reduction (TPR) reveals that air calcining at 250°C does not provide the complete conversion of the original nickel nitrate to oxide; nickel nitrates and hydroxynitrates are present in the catalyst precursors; their content decreases upon modification with the HPA. Differences in the composition and strength of Lewis acid sites on the surface of two types of Al2O3 lead to dissimilar coordination of nitrate and differences in nickel reducibility, as revealed by TPR, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy with CO adsorption, and in situ X-ray photoelectron spectroscopy (XPS). Nickel contained in Ni/Al2O3(E) undergoes reduction somewhat more readily than nickel in Ni/Al2O3(A) does; however, the conditions used in this study provide the reduction of only a small portion of nickel in the two catalysts. According to in situ XPS, TPR, and DRIFT spectroscopy with CO adsorption, the modification of Ni/Al2O3 with the HPA leads to a further change in the acidic properties and the coordination of nickel nitrate during impregnation and an increase in nickel reducibility; it prevents nickel from migration from the surface into the bulk of the sample and leads to the formation of new active sites owing to the strong nickel–tungsten interaction in the HPA. Depending on the nature of the support, modification with the HPA leads to an improvement (Ni/HPA/Al2O3(A)) or deterioration (Ni/HPA/Al2O3(E)) of the catalytic efficiency of the samples. At high temperatures, the benzene selectivity of the HPA-modified catalysts decreases owing to the formation of cyclohexane. The catalyst efficiency increases in the following order: Ni/HPA/Al2O3(E) < Ni/Al2O3(A) < Ni/Al2O3(E) < Ni/HPA/Al2O3(A). The most active catalyst—Ni/HPA/Al2O3(A)—exhibits the highest stability in long-term tests with an increase and subsequent decrease in temperature. The effect of nickel reducibility on the catalyst efficiency in CB hydrodechlorination is more significant than the effect of differences in texture and nickel content.

A model is proposed for intensification of the process of high-temperature vacuum removal of iron impurities from microporous aluminum oxide via purging of the particle layer with argon. In the temperature range characteristic of this process, the pressure of saturating vapors above pure iron is on the order of 0.1 mm Hg. For an impurity with a concentration of several particles per million, the figure is proportionally smaller, and this creates problems with evacuation of the chamber. The use of argon as a carrier gas destroys the rigid connection between the partial vapor pressure of the impurity and the pressure in the vacuum chamber. Calculations show that the argon flow under moderate vacuum 10–5 mm Hg with a mass flow rate on the order of 10–7 kg/(m2 s) provides a very deep purification.

We have examined the feasibility of preparing high-purity aluminum oxide by oxidizing granulated aluminum in a 0.1 M potassium hydroxide solution, followed by heat and acid treatments of the oxidation products. The aluminum oxidation product, consisting of two phases of Al(OH)3 (bayerite and gibbsite), was first heat-treated at temperatures of 300, 600, 900, and 1200°C; then treated with hydrochloric acid; and calcined at a temperature of 1450°C. It has been shown that raising the preheat treatment temperature increases the total concentration of impurities, including Fe impurities, but reduces the concentration of alkali metals (K, Na, and Li). Using 99.7%-pure aluminum, we have prepared aluminum oxide with a purity at a level of 99.886%. Using 99.98%-pure aluminum, we have obtained aluminum oxide with a purity at a level of 99.993%.

Catalytic systems 2 wt % Pd/Al 2 O 3 were prepared using noncalcined boehmite (NC) and two types of alumina support: one was prepared by the calcination of boehmite at 600°C (C) and the other produced by Engelhard (E). To prepare 2 wt % Pd/HPC–Al 2 O 3 samples, these supports were modified by impregnation by a heteropoly compound (HPC) (20 wt % Н 8 [Si(W 2 O 7 ) 6 ] ⋅ 6Н 2 О). The effect of the Al 2 O 3 structure and its modification by the heteropoly compound on the physicochemical properties, activity, selectivity and stability of catalysts in the reaction of multiphase hydrodechlorination of 1,3,5-trichlorobenzene (TCB) was studied. All catalysts showed activity in the considered reaction with the predominant formation of benzene but were deactivated in the reaction medium. Modification by the heteropoly compound resulted in increased stability and was especially effective for catalyst supported on Al 2 O 3 (E). The method of scanning electron microscopy (SEM) was used to determine the morphological differences of supports. According to the data of transmission electron microscopy, all catalysts contained palladium in the form of particles less than 20 nm in size. The particle size and width of the size distribution increases in the series Pd/Al 2 O 3 (NC) < Pd/Al 2 O 3 (C) < Pd/Al 2 O 3 (E). Modification by the heteropoly compound was favorable for the decrease in the size of palladium particles. The method of temperature-programmed reduction with hydrogen (TPR-H 2 ) showed that all catalysts included in their composition palladium hydride along with more strongly surface-bound metal forms that are reduced at elevated temperatures, and their content decreases after modification by the heteropoly compound and increases after catalytic tests. According to diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the deposition of a heteropoly compound leads to a change in the type of Lewis acid sites on the alumina surface and in the electronic state of palladium. According to the results of infrared spectroscopic studies of adsorbed CO, the relatively large particles of Pd 0 are the main form on the surface of nonmodified catalysts. The catalysts modified by the heteropoly compound contain single Pd + and Pd 2+ cations, and the fraction of Pd 0 is substantially smaller. The specific features of the Lewis acidity of the catalyst surface determine the possibility of 1,3,5-trichlorobenzene adsorption and activation on the support and the spillover of hydrogen from Pd 0 . An increase in the catalyst stability as a result of support modification by the heteropoly compound can be explained by the appearance of new active sites in the interaction of palladium with the heteropoly compound or its thermal decomposition products.

The experiments were carried out to show that it was possible to raise the chemical purity of the electrically fused alumina powders by means of the high-temperature (about 1750 °C) vacuum (about 10–5 mm Hg) roasting. Three samples of the commercial fused corundum were heat-treated, the samples having different size grading and impurity composition, after the treatment the impurity level turned out to be ten times as less: the samples were almost completely cleared off Na, Mg, K, Mn, Cu and Zn impurities, the iron content decreased by the factor of 8‒10. It was determined that the samples were built up of the porous pellets of the size of 16‒60 microns, formed out of the solid micro-particles of the size of 0,4‒0,7 microns. The pellets' specific surface area was within the 2,8 and 3,3 cm/gram.

Two methods (spraying and calendering) for fabrication of supercapacitor electrodes are considered. Results of tests of double-layer capacitors with aqueous (sulfuric acid) and organic (tetraethylammonium tetrafluoroborate dissolved in acetonitrile) electrolytes and electrodes fabricated from activated carbon are presented. It is shown that, depending on the type of the electrolyte, it is necessary to use different methods for fabrication of carbon electrodes.