Mechanochemical Synthesis of Layered Double Hydroxides as a Promising Method for the Preparation of Adsorbents and Catalysts

Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of...     

Palladium hydrogenation catalyst based on a porous carbon material obtained upon the dehydrochlorination of a chloro polymer

The applicability of a porous carbon material obtained as a result of the “chemical” dehydrochlorination of chlorinated polyvinyl chloride as a support for palladium hydrogenation catalysts was demonstrated. The efficiency of the catalyst was evaluated in the liquid-phase reactions of nitrobenzene hydrogenation and chlorobenzene hydrodechlorination. Although the specific activity of the catalyst was lower by a factor of 3–4 than that of the samples based on Sibunit and carbon nanotubes, the complete conversion of the initial compounds with the selective formation of end products under mild conditions was achieved at a relatively low palladium content (1.5%).     

The Role of the Stage of Metal Complex Deposition on Support in the Properties Formation of Supported Platinum Catalysts

Kinetics and Catalysis - The subject of this review is related to the development of research on the mechanism of interaction of platinum complex compounds, primarily, H2[PtCl6], with alumina...     

Catalysts Pt/(Ga)Al2O3 Obtained Using Aluminum Metal Activated with Gallium

Russian Journal of Applied Chemistry - The products of the interaction of activated aluminum with water were used as a precursor of an oxide support of catalysts. The possibility of changing the...     

Synthesis of Mg<Superscript>2+</Superscript>-, Al<Superscript>3+</Superscript>-, and Ga<Superscript>3+</Superscript>-containing layered hydroxides and supported platinum catalysts based thereon

The effect of the cationic composition of MgAl(Ga) layered double hydroxides on the structure, texture, and acid–base properties of related oxide supports for platinum catalysts has been investigated. As gallium is progressively substituted for aluminum in the mixed oxide, the properties of the support change only slightly, while the activity of the Ga–Pt catalysts in propane conversion increases, the propylene selectivity remains high (99%), and C–C bond hydrogenolysis is hampered.     

Influence of a doubly charged cation nature on the formation and properties of mixed oxides MAlO x (M = Mg2+, Zn2+, Ni2+) obtained from the layered hydroxide precursors

Influence of the nature of a doubly charged cation in the layered double hydroxides (LDH) on the conditions of formation and properties of mixed oxide phase MAlO _x (M = Mg²⁺, Zn²⁺ and Ni²⁺), its ability to reconstruct the structure of the original precursor under contact with water has been studied. Hydrotalcite-like compounds and corresponding oxides with different M²⁺: M³⁺ ratio were investigated by XRD, TEM, TG-DTG-DTA, ²⁷Al NMR, N₂ adsorption, and differentiating dissolution. It has been found that the nature of the cation M²⁺ influences the conditions of LDH thermal decomposition, structural and textural characteristics of the formed mixed oxides. The obtained data can be used to synthesize the oxide supports with desired acid-base and adsorption properties.     

Hydroisomerization of benzene-containing gasoline fractions on a Pt/SO 42? -ZrO2-Al2O3 catalyst: II. Effect of chemical composition on acidic and hydrogenating and the occurrence of model isomerization reactions

The acidic and hydrogenating of Pt/SO₄²⁻-ZrO₂-Al₂O₃ samples containing from 18.8 to 67.8 wt % Al₂O₃ as a support constituent were studied by the IR spectroscopy of adsorbed CO and pyridine, and the model reactions of n-heptane and cyclohexane isomerization on these catalysts were examined. The total catalyst activity in the conversion of n-heptane decreased with the concentration of Al₂O₃; this manifested itself in an increase in the temperature of 50% n-heptane conversion from 112 to 266°C and in an increase in the selectivity of isomerization to 94.2%. In this case, the maximum yield of isoheptanes was 47.1 wt %, which was reached on a sample whose support contained 67.8 wt % Al₂O₃. A maximum yield (69.6 wt %) and selectivity (93.7%) for methylcyclopentane formation from cyclohexane were also reached on the above catalyst sample. This can be explained by lower concentrations of Lewis and Br?nsted acid sites in the Pt/SO₄²⁻-ZrO₂-Al₂O₃ system, as compared with those in Pt/SO₄²⁻-ZrO₂. The experimental results allowed us to make a preliminary conclusion that the Pt/SO₄²⁻-ZrO₂-Al₂O₃ catalyst whose support contains 67.8 wt % Al₂O₃ is promising for use in the selective hydroisomerization of benzene-containing gasoline fractions in the thermodynamically favorable process temperature range of 250–300°C.     

Spin-Flop Transition in Co2B2O5 Pyroborate

JETP Letters - Recent theoretical ideas concerning the mechanism of the electromagnetic proximity effect in hybrid superconducting structures with ferromagnetic layers, as well as the problem of...     

Effect of the nature of the active-component precursor on the properties of Pt/MgAlO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> catalysts in propane and <Emphasis Type="Italic">n</Emphasis>-decane dehydrogenation

The Pt/MgAlO _x catalysts, in which a mixed aluminum–magnesium oxide obtained by the heat treatment of corresponding layered double hydroxides was used as a support, were studied. The effects of the nature of active-component precursors ([PtCl₆]^2–, [PtCl₄]^2–, and [Pt₃(CO)₆] ₆ ^2- ), and the Mg/Al ratio in the support on the anchoring of complexes, the disperse state of platinum, and the properties of the obtained catalysts in the reactions of propane and n-decane dehydrogenation were found.     

Preparation of Ultramicroporous Materials by Fluidized-Bed Pyrolytic Deposition of Carbon in Pores of a Carbon Matrix

Samples of microporous materials were prepared by pyrolytic deposition of carbon from divinyl in a fluidized bed reactor onto carbon supports obtained from coconut and pine nut shells. The influence exerted on the adsorption capacity for CO2 by the divinyl pyrolysis temperature (in the range 600–750°С) and degree of densification (in the range 6–22%) was studied. Carbon deposition conditions ensuring the specific surface area (S_BET) lower than 5 m2 g^–1 at the adsorption capacity for СО₂ higher than 1 mmol g^–1 for both samples were found.