The kinetics of oxidation of aluminum electroexplosive nanopowders during heating in air

The rules governing the oxidation of aluminum nanopowders obtained by the electrical explosion of wires during heating in air under the conditions of linearly increasing temperature and in isothermal regime were studied. The influence of the composition and structure of aluminum particle oxide coating and metallic core on the parameters of the process and the phase composition and morphology of oxidation products was determined. Thermal reaction conditions were shown to depend on thermogravimetry regime, and the kinetic data were used to explain this dependence. The kinetics of oxidation was modeled taking into account the aluminum particle-size distribution function. It was shown that the structures of particles of the nanodisperse and micron electroexplosive powder fractions were different.     

Influence of the modification process on the properties of AlOOH nanofibers

A procedure of bulk modification of aluminum oxhydroxide AlOOH during synthesis using manganese(II) ion as the modifying agent was studied. The physicochemical properties of the modified AlOOH fiber were examined. It was found that the presence of manganese(II) ions in solution affected the composition of the products of the reaction between aluminum nanopowder and “liquid water.” The phase composition of the reaction products was examined by X-ray diffraction and differential thermal analysis techniques. It was shown that, for solutions with the manganese ion concentration varying from 0.02 × 10^?3 to 40 × 10^?3 mol l^?1, the degree of amorphicity and the proportion of the AlOOH phase tended to increase. A modification mechanism involving the participation of manganese ions in the AlOOH nanofiber growth process was proposed.     

Oxidation of activated aluminum with water as a method for hydrogen generation

The activation of aluminum with low-melting gallium-based alloys makes it possible to obtain a material easily oxidizable by water at room temperature to release ~1.2 L of pure hydrogen per 1 g of metal. The kinetics and regularities of the interaction of activated aluminum with water were studied as a function of the amount and composition of metal activators, dispersity of the powder, and temperature. The phase composition of the solid reaction products was shown by X-ray diffraction analysis to depend on temperature and duration of the process.     

Interaction of Aluminum Metaphosphates in the Setting of Potassium Silicate Solutions in Terms of the Crystalline Phase Composition.

Aluminum phosphates are known as inorganic hardening agents for the setting of alkali silicate solutions, but only few studies have been published on the setting mechanism of potassium water glass. The solution behavior of two aluminum metaphosphates in alkaline environments were investigated photometrically determining the dissolved aluminum content. The crystalline phase composition of the hardened potassium silicate systems was determined by X-ray diffraction. New insights into the setting mechanism were obtained concerning the structure of the aluminum metaphosphate and the SiO₂/K₂O ratio of three different potassium silicate solutions. With increasing pH value aluminum tetrametaphosphate reacts rapidly and forms crystalline potassium tetrametaphosphate dihydrate by an ion-exchange-reaction. In parallel, a depolymerization of the cyclic metaphosphate structure occurs leading to potassium dihydrogen phosphate as final fragmentation product. With aluminum hexametaphosphate no ion-exchange reaction product was observed. Only potassium dihydrogen phosphate could be found in higher quantities compared to the reaction with aluminum tetrametaphosphate.     

Synthesis of Aluminum Monooxycarbide

Formation of aluminum monooxycarbide is accompanied by formation of intermediate phases in the course of high-temperature reduction of aluminum oxide with carbon. The influence of the reaction conditions (dispersity of the initial oxide, temperature, time, and composition of the gas phase in the reaction zone) on the structural characteristics of the crystalline products was studied.     

Hydrolysis of aluminum sulfates in the presence of ammonium sulfite

Hydrolysis of aluminum sulfate and potash alum in the presence of an ammonium sulfite additive in the temperature range T _boil-200°C was studied. A possible reaction mechanism was suggested. The composition and structure of the precipitates formed were determined and certain differences in their morphology were noted. Recommendations for practical implementation of the method of hydrolytic recovery of aluminum from solutions of its sulfate salts were given.     

Synthesis and thermal transformations of allyl aryl ethers of adamantane series

Allyl aryl ethers of adamantane series were obtained by reacting (E)-1-(adamant-1-yl)-3-bromoprop-1-ene with phenol or ethyl salicylate. The features of thermal transformations of allyl aryl ethers containing bulky adamantane scaffold were investigated. It has been found that the composition of the reaction products is largely dependent on temperature, time and nature of the solvent. When a nucleophilic solvent was used, the reaction proceeded via formal substitution of phenoxy fragment with nucleophilic species prevailing in the reaction medium.     

Photothermal degradation of copolymers of methyl methacrylate and n-butyl acrylate

The photothermal degradation of copolymers of methyl methacrylate (MMA) and n-butyl acrylate (n-BuA) covering the whole composition range has been studied at 165°.The gaseous products, which are relatively minor, are hydrogen, carbon monoxide and methane. The liquid products are predominantly MMA, with n-BuA, n-butanol and n-butyraldehyde as minor products. Infra-red spectral changes in the residue were attributed to lactone formation and associated with butanol formation as in the purely thermal reaction The “cold ring” or chain fragment fraction becomes increasingly more abundant as the n-BuA content of the copolymer is increased.All the products and principal features of the reaction are explained in terms of a radical process which is initiated by scission of pendant acrylate units and is propagated by a combination of depropagation and intra- and intermolecular transfer processes, the relative importance of which depends upon copolymer composition. Differences from the thermal reaction and the corresponding reaction in copolymers of methyl methacrylate and methyl acrylate are discussed.     

Molecular Complexes of μ-Carbidodimeric Iron(IV) Tetra-4-<Emphasis Type="Italic">tert</Emphasis>-butylphthalocyaninate with Nitrogenous Bases

The reaction of μ-carbidodimeric iron(IV) tetra-4-tert-butylphthalocyaninate with nitrogenous bases (imidazole and its derivatives, pyridine, diethylamine), which involves formation of donor?acceptor complexes with a preserved dimeric structure, was studied by spectral methods. The composition of such molecular complexes and their comparative stability were determined. The coordination power of μ- carbidodimeric iron(IV) tetra-4-tert-butylphthalocyaninate was found to depend on the nature of the nitrogenous base and macrocycle. Quantum-chemical modeling of the coordination reaction was performed. The energetic and geometric characteristics of the donor?acceptor complexes were obtained. The composition of the reaction products was shown to be affected of the degree of deformation of the macrocycle.     

Preparation of hollow carbon nanospheres at low temperature via new reaction route

Hollow carbon nanospheres were obtained at 200 °C via a new reaction route, by using magnesium, hexachloroethane and aluminum trichloride as starting materials and benzene as solvent. The products were characterized with X-ray diffraction pattern, transmission electron microscope, high-resolution transmission electron microscope images and Raman spectrum. The reaction conditions are easy to be maintained and controlled. They may provide a new method to produce other carbonaceous materials. A possible mechanism of reaction was proposed.     

Electrodeposition of Aluminum from AlCl3/Et3NHCl Ionic Liquids

Aluminum was successfully electrodeposited on Al electrodes from aluminum chloride (AlCl₃)/triethylamine hydrochloride (Et₃NHCl) ionic liquids by the constant potential electrolysis. Electrical conductivities of AlCl₃/Et₃NHCl ionic liquids were measured as a function of the temperature and composition. The nucleation processes and the influence of experimental conditions on the current efficiency and surface morphology of aluminum electrodeposits were studied on Al electrodes from 2:1 molar ratio AlCl₃/Et₃NHCl ionic liquid. The electrical conductivities of ionic liquids increased as the electrolyte temperature increased, following the Arrhenius behavior. Analyses of the chronoamperograms indicated that the deposition process of aluminum on Al substrates was controlled by instantaneous nucleation with diffusion-controlled growth. Constant potential deposition experiments showed that the electrodeposits obtained on Al electrodes were dense, continuous, and well adherent, and the current efficiency was 73% at −2.4 V(vs Pt) for 20 min electrolysis at room temperature. The purity of aluminum electrodeposits on Al electrodes was above 96% (w).     

Comparative study of the synthesis of layered transition metal molybdates

Mixed metal oxides (MMOs) prepared by the mild thermal decomposition of layered double hydroxides (LDHs) differ in their reactivity on exposure to aqueous molybdate containing solutions. In this study, we investigate the reactivity of some T-Al containing MMOs (T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates (LTMs) possessing the general formula AT₂(OH)(MoO₄)₂·H₂O, where A=NH₄⁺, Na⁺ or K⁺. The phase selectivity of the reaction was studied with respect to the source of molybdate, the ratio of T to Mo and the reaction pH. LTMs were obtained on reaction of Cu-Al and Zn-Al containing MMOs with aqueous solutions of ammonium heptamolybdate. Rehydration of these oxides in the presence of sodium or potassium molybdate yielded a rehydrated LDH phase as the only crystalline product. The LTM products obtained by the rehydration of MMO precursors were compared with LTMs prepared by direct precipitation from the metal salts in order to study the influence of preparative route on their chemical and physical properties. Differences were noted in the composition, morphology and thermal properties of the resulting products.     

Catalytic degradation of polyolefins over hexagonal mesoporous silica: Effect of aluminum addition

Degradations of polypropylene (PP) and polyethylene (PE) over pure hexagonal mesoporous silica and aluminum-containing hexagonal mesoporous silica catalysts were studied in a fixed bed catalytic reactor at 380 and 430 °C, respectively. The thermal and catalytic degradations of both PP and PE in liquid-phase-contact and vapor-phase-contact modes over pure hexagonal mesoporous silica had no significant effect on the product yields. The liquid products were widely distributed in hydrocarbons with boiling point ranges of 36–405 °C. By adding a small amount of aluminum to the hexagonal mesoporous material, aluminium-containing hexagonal mesoporous silica exhibited good performance in cracking heavy molecular weight hydrocarbons into light hydrocarbons. High liquid yields and less coke deposits were obtained in liquid-phase-contact reaction with increasing aluminum content. The liquid products were mainly composed of C₅–C₁₀ hydrocarbons with boiling points of 36–174 °C, and propene, butene, and butane were main components in gaseous products. The effect of degradation temperature was not observed on product yields though degradation rate of polyolefin into liquid products was faster. Conversely, in vapor-phase-contact reaction, an increase in gaseous yield was observed when increasing the amount of aluminum and temperature of the cracking reactor, while the residue yield remained constant.     

Vanadium-catalyzed oxidative bromination promoted by Brønsted acid or Lewis acid

The oxidative bromination of arenes was induced by a vanadium catalyst in the presence of a bromide salt and a Brønsted acid or a Lewis acid under molecular oxygen, which provides an eco-friendly bromination method as compared with a conventional bromination one with bromine. This catalytic reaction could be applied to the bromination of alkenes and alkynes to give the corresponding vic-bromides. Use of aluminum halide as a Lewis acid in place of a Brønsted acid was demonstrated to provide a more practical protocol for the oxidative bromination. From ketones, α-bromination products were obtained. AlBr₃ was found to serve as both a bromide source and a Lewis acid to induce the bromination smoothly. ⁵¹V NMR experiment showed that this catalytic bromination is likely to depend on the redox cycle of a vanadium catalyst under molecular oxygen.     

Discovery of Novel Sultone Fused Berberine Derivatives as Promising Tdp1 Inhibitors

A new type of berberine derivatives was obtained by the reaction of berberrubine with aliphatic sulfonyl chlorides. The new polycyclic compounds have a sultone ring condensed to C and D rings of a protoberberine core. The reaction conditions were developed to facilitate the formation of sultones with high yields without by-product formation. Thus, it was shown that the order of addition of reagents affects the composition of the reaction products: when sulfochlorides are added to berberrubine, their corresponding 9-O-sulfonates are predominantly formed; when berberrubine is added to pre-generated sulfenes, sultones are the only products. The reaction was shown to proceed stereo-selectively and the cycle configuration was confirmed by 2D NMR spectroscopy. The inhibitory activity of the synthesized sultones and their 12-brominated analogs against the DNA-repair enzyme tyrosyl-DNA phosphodiesterase 1 (Tdp1), an important target for a potential antitumor therapy, was studied. All derivatives were active in the micromolar and submicromolar range, in contrast to the acyclic analogs and 9-O-sulfonates, which were inactive. The significance of the sultone cycle and bromine substituent in binding with the enzyme was confirmed using molecular modeling. The active inhibitors are mostly non-toxic to the HeLa cancer cell line, and several ligands show synergy with topotecan, a topoisomerase 1 poison in clinical use. Thus, novel berberine derivatives can be considered as candidates for adjuvant therapy against cancer.     

Oligomerization of 1-decene under the action of catalytic systems based on Al-aluminum activator-RCl and Al-RCl

Novel catalytic systems for the cationic oligomerization of 1-decene into synthetic poly(α-olefin) oils have been worked out; these systems include a highly disperse (0.1–40 μm) aluminum, an aluminum activator [I₂, Mg, (C₂H₅) _n AlCl_{3 ? n} , (CH₃)₃CCl and some other RX, HCl, benzene, and toluene], and a cocatalyst based on organic halide compounds RX (R is primary, secondary, or tertiary alkyl, allyl, or benzyl; X is Cl, Br, or I). We study the effect of various factors (characteristics of Al, nature of aluminum activator, RCl: Al molar ratio in the catalyst, concentration of Al, temperature, benzene additives, reaction duration) on the conversion of 1-decene into poly(α-olefins), the fractional composition of oligomerization products, the content of chlorine in poly(α-olefins), and the structure and physicochemical characteristics of fractions.     

Methods of preparation and properties of mineral-carbon sorbents obtained from coal-tar pitch-polymer compositions

The purpose of this study was to determine the possibility of producing hydrophobic mesoporous mineral-carbon sorbents from aluminum hydroxide and coal-tar pitch-polymer compositions by carbonization at 600?°C in an nitrogen atmosphere. The method of homogenization was optimized using different solvents. Blends of aluminum hydroxide and coal-tar pitch with a definite composition or the products of co-precipitation of aluminum hydroxide in the coal-tar pitch-polymer medium were subjected to carbonization process. The hydrophilic?Chydrophobic properties were evaluated by adsorption of water vapors. The highest value of BET surface area about 370?m²/g, was achieved for the carbonization product obtained from co-precipitated raw components with 10?wt% coal-tar pitch-polymer compositions.     

Study on the In-situ Synthesis of Aluminum Titanate Sintered by Waste Aluminum Slag

Aluminum titanate was in-situ synthesized by using industrial waste-residue in the aluminum factory and TiO2 as the main raw materials and the influence of different reaction temperatures on the purity and microstructures of synthesized products were mainly discussed. The obtained Al2TiO5 was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and relevant analytical software. The results show that elevating the sintering temperature can increase the content of aluminum titanate; and at 1420 ℃, it reaches the highest in the synthesized ceramic. When the sintering temperature continues to increase, the produced aluminum titanate will decompose resulting in the drop of its content. Therefore, the optimum sintering temperature of in-situ synthesis of aluminum titanate is determined as 1420 ℃, at which the grains of aluminum titanate grow completely, the purity of aluminum titanate is 89.3wt%., the highest density is 2.75 g/cm^3, and the porosity is 9%.     

Catalytic Activity of Thermolyzed [Co(NH3)6][Fe(CN)6] in CO Hydrogenation Reaction

Currently, the processes of obtaining synthetic liquid hydrocarbons and oxygenates are very relevant. Fischer-Tropsch synthesis (FTS) is the most important step in these processes. The products of thermal destruction in argon of the mixture [Co(NH₃)₆][Fe(CN)₆] and Al(OH)₃ were used as catalysts for CO hydrogenation. The resulting compositions were studied using powder X-ray diffraction, IR spectroscopy, elemental analysis, SEM micrographs. The specific surface area, pore and particle size distributions were determined. It was determined that the DCS-based catalysts were active in the high-temperature Fischer-Tropsch synthesis. The effect of aluminum in the catalyst composition on the distribution of reaction products was revealed.     

Advanced analytical methods for the structure elucidation of polystyrene-b-poly(n-butyl acrylate) block copolymers prepared by reverse iodine transfer polymerisation

Reverse iodine transfer polymerisation (RITP) is a living radical polymerisation technique that has shown to be feasible in synthesising segmented styrene-acrylate copolymers. Polymers synthesised via RITP are typically only described regarding their bulk properties using nuclear magnetic resonance spectroscopy and size exclusion chromatography. To fully understand the complex composition of the polymerisation products and the RITP reaction mechanism, however, it is necessary to use a combination of advanced analytical methods. In the present RITP procedure, polystyrene was synthesised first and then used as a macroinitiator to synthesise polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers. For the first time, these PS-b-PBA block copolymers were analysed by a combination of SEC, in situ¹H NMR and HPLC. ¹H NMR was used to determine the copolymer composition and the end group functionality of the samples, while SEC and HPLC were used to confirm the formation of block copolymers. Detailed information on the living character of the RITP process was obtained.