A. B. Arbuzov

Chemical composition optimization and characterization of the NiO/B2O3-Al2O3 system as a catalyst for ethylene oligomerization

The samples of the NiO/B2O3-Al2O3 system with NiO contents from 0.48 to 38.30 wt % were synthesized by the impregnation of borate-containing alumina (20 wt % B2O3). It was found that nickel oxide occurred in an X-ray amorphous state in the samples containing to 23.20 wt % NiO. At a NiO content of 4.86 wt % or higher, the support was blocked by the modifier to cause a decrease in the specific surface area from 234 to 176 m2/g and in the amount of acid sites from 409–424 to 333 μmol/g. An extremal character of the dependence of catalyst activity in ethylene oligomerization on NiO content was found with a maximum in the range of 4.86–9.31 wt %. Based on spectroscopic data, it was found that ethylene activation on the NiO/B2O3-Al2O3 catalyst can be associated with the presence of Ni2+ cations, which chemically interact with the support. The catalyst containing 4.86 wt % NiO at 200°C, a pressure of 4 MPa, and an ethylene supply rate of 1.1 h−1 provided almost complete ethylene conversion at the yield of liquid oligomerization products to 90.0 wt %; the total concentration of C8+ alkenes in these products was 89.0 wt %.

Liquid-phase isobutane alkylation with butenes over aluminum chloride complexes synthesized in situ from activated aluminum and tert -butyl chloride

The liquid-phase interaction between isobutane and butenes at 303 K and 2.5–3.0 MPa has been investigated using activated aluminum (Al*)-tert-butyl chloride (TBC) model system (TBC: Al* = 0.35−4 mol/mol). It has been demonstrated by attenuated total reflection FT-IR (ATR-FT-IR) spectroscopy that the catalytically active aluminum chloride complexes forming in situ in the hydrocarbon medium vary in composition. Alkylation as such takes place at equimolar proportions of the reactants (TBC: Al* = 1: 1) and butenes feed 1mass flow rate of 5 h−1 per gram of Al*. According to ATR-FT-IR data, the most abundant aluminum complexes resulting under these conditions are the AlCl4− and Al2Cl7− ions and, probably, the molecular complex AlCl3 · sec-C4H9Cl. In a fourfold excess of TBC over Al* at butenes mass feed rate of 2.5 h−1, isobutane undergoes self-alkylation. In this case, the Al2Cl7− ion is not detected and the most abundant complexes are AlCl4−, Al3Cl10− and the molecular species AlCl3 · tert-C4H9Cl. It is hypothesized that the Al2Cl7− ion plays the key role in the liquid-phase alkylation of isobutane with butenes.

Mechanochemical synthesis of nanocrystalline nickel-molybdenum compounds, their morphology and application in catalysis: I. Effect of the Ni: Mo atomic ratio on the structure and properties of nickel-molybdenum compounds prepared under mechanochemical synthesis conditions

Mechanochemical activation in high-energy planetary activators was used for the preparation of highly dispersed nickel-molybdenum compounds. Nickel hydroxocarbonate [NiCO3 · 2Ni(OH)2 · nH2O] and ammonium paramolybdate [(NH4)6Mo7O24 · 4H2O] were chosen as starting compounds. The effect of the Ni: Mo atomic ratio on the composition and structure of products formed in the process of mechanochemical activation followed by calcination was studied. It was found that, at the Ni: Mo atomic ratios of 1.0 and 1.4, the mechanically activated product after calcination at 520°C contained 70–100% β-NiMoO4, which is a stable phase at temperatures lower than 180°C.

Hydroisomerization of benzene-containing gasoline fractions on a Pt/SO42−-ZrO2-Al2O3 catalyst: III. The hydrogenating properties of the catalyst

The properties and state of platinum in Pt/SO42−-ZrO2-Al2O3 catalysts with various alumina contents have been investigated in benzene hydrogenation as a model reaction using IR spectroscopy, temperature-programmed reduction, and H2 chemisorption. As the Al2O3 content is raised, the hydrogenating activity of the catalyst increases, which is due to the increasing proportion of metallic platinum on the surface.

Structural and morphological transformations of carbon nanospheres during high-temperature, high-pressure processing

This paper presents analysis of structural changes in powders consisting of turbostratic carbon spheres with an average particle diameter of 250 and 25 nm after high-temperature, high-pressure processing at a pressure of 8 GPa. It has been shown that marked ordering of graphene sheets is observed at 1300°C and actively proceeds at higher temperatures. The major morphological species in the samples after processing is slabs of graphene sheets, and three-dimensional structural perfection is higher at the smaller particle size. Using high-resolution electron microscopy, samples of this powder were shown to contain diamond nanocrystallites.

Elemental and phase composition, morphology, and chemical features of the surface of Al–Ni Alloys in contact with liquid Ga–In eutectic

A set of aluminum–nickel alloys has been studied. The elemental composition of the samples has been determined by atomic emission and atomic absorption spectrometry. X-ray diffraction analysis has revealed that the alloying of the metals leads to the formation of Al3Ni and Al3Ni2 intermetallic compounds, while a portion of Al remains in a metallic phase. The local chemical composition and surface morphology of the original alloys and the alloys activated with the liquid Ga–In eutectic have been studied by scanning electron microscopy and X-ray microanalysis. It has been shown that the original alloys are characterized by a pronounced morphological heterogeneity of interfacial regions in the near-surface layers. It has been found that the studied Al–Ni alloys are activated by the liquid Ga–In eutectic; however, one of the alloy components—the Al3Ni intermetallic compound—does not undergo significant morphological and chemical changes in contact with the liquid eutectic.

Hydrocracking of vegetable oil on boron-containing catalysts: Effect of the nature and content of a hydrogenation component

Catalysts based on metals (Pt, Pd) and metal oxides (NiO, Co3O4, MoO3, WO3), supported on the surface of borate-containing aluminum oxide (B2O3–Al2O3), in the hydrocracking of sunflower oil at a temperature of 400°C, a pressure 4.0 MPa and a mass hourly space velocity MHSV 5.0 h–1 are compared. H2 TPR and IR spectroscopy of adsorbed CO and ESDR show that the hydrogenation catalyst components are Pt0 and Pd0, a mixture of Ni2+ + Ni0, Co2+ + Co0, or a mixture of the highest and partially reduced oxides of Mo and W. It is established that catalysts containing Pt, Pd, NiO and Co3O4, ensure complete oil hydrodeoxygenation. The main oxygen removal reactions in Ptand Pd-systems are decarboxylation and hydrodecarbonylation. For catalysts with NiO and Co3O4, characteristic reactions are reduction and methanation. The highest yield of the diesel fraction was obtained on Pt/B2O3-Al2O3 catalysts with metal contents of 0.3–1.0 wt %. Along with n-alkanes, the diesel fractions obtained on these catalysts include cycloalkanes and iso-alkanes (up to around 40 wt %) and aromatic hydrocarbons present in trace amounts. Hydrocracking on the Pt system at 400°C for 20 h with MHSV of 1.0 h–1 produces a diesel fraction with a yield of at least 82.0 wt % and the content of iso-alkanes at least 76.1 wt %.

Features of the surface structure of Al-Cu alloys before and after reaction with the liquid Ga-In eutectic

The structural, morphological, and chemical characteristics of aluminum-copper alloys before and after contact with the liquid Ga-In eutectic have been studied. X-ray diffraction (XRD) analysis has revealed that alloying results in the formation of Al9Cu11.5 and Al2Cu intermetallic compounds and CuAl0.005, CuAl0.14, and AlCu0.004 substitutional solid solutions. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) have shown that, for the CuAl0.005 and CuAl0.14 substitutional solid solutions of aluminum in copper and the individual Al9Cu11.5 intermetallic compound in contact with the liquid Ga-In eutectic, surface spreading of the eutectic without any significant morphological and chemical changes in the studied systems is observed. At the same time, the alloy containing the Al2Cu intermetallic compound and the phase of the AlCu0.004 substitutional solid solution of copper in aluminum interacts with liquid Ga-In eutectic owing to the activation of aluminum as a solid solution component. This activated Al-Cu alloy reacts with liquid tert-butyl chloride in the presence of ethylene to form catalyst Al-Cu-Cl complexes in situ. It has been speculated that these complexes are mostly formed owing to the dissolution of the phase of the AlCu0.004 substitutional solid solution of copper in aluminum in a medium of liquid tert-butyl chloride.

The Influence of the Specific Surface Area of the Carbon Support on the Activity of Ruthenium Catalysts for the Ammonia-Decomposition Reaction

A method for fractionation of the starting carbon composite Sibunit by density was used to obtain three samples of Sibunit with different values of the specific surface area: Sib10 at 439 m2/g, Sib13 at 389 m2/g, and Sib17 at 256 m2/g. Investigation of Sibunits using both methods, that is, X-ray diffraction analysis and combination (Raman) scattering spectroscopy, did not reveal significant differences (the parameters of the crystal lattice and the ID/IG ratio). The fractionated supports were used to obtain Ru-containing catalysts for ammonia decomposition reaction (0.1 MPa, 400°C). The dependence of the specific catalytic activity calculated per 1 m2 of the support specific surface a for catalysts of the same composition (4.0% Ru and 13.6% Cs) has an extreme form. The authors connect this with two factors: the blocking support pores contain an active component and a change in features of ruthenium interactions with the promoter (Cs) of the catalyst.

Influence of Mechanical Activation Parameters on the Aggregate Size, Texture, and Functional Composition of the Surface of Carbon Black

The influence of mechanical activation parameters (acceleration of milling bodies and activation time) on the morphology, texture, and functional composition of the surface of P514 and N375 carbon black was studied. Mechanical activation of carbon black leads to a decrease in the carbon black aggregate size and in the dibutyl phthalate adsorption and to an increase in the ash residue. Rubber stocks were prepared from SKMS-30 ARK rubber and mechanically activated carbon black, and their physicomechanical properties after vulcanization were determined.