Search

Based on the Sibunit carbon composite, Ru–Cs(Ba)/Sibunit catalysts with Cs(Ba) : Ru molar ratios of 0.5, 1.5, and 2.5 were obtained. The catalytic activity of the obtained promoted catalysts in the decomposition of ammonia and their thermal resistance to methanation are compared. In the reaction of ammonia decomposition, the specific activity (Wsp) of barium-containing catalysts proved to be 2 times lower than the specific activity of cesium-containing samples with the same molar M : Ru ratio. Thus, Wsp at 500°С was 29.4 mmol H2 min–1 for 0.5Cs–Ru/Sibunit and 15.4 mmol H2 g–1cat min–1 for 0.5Ba–Ru/Sibunit. It was shown that the introduction of barium at molar ratios Ba : Ru = of 0.5–2.5 significantly increases the thermal stability of the samples defined as the ratio of the weight of hydrogen obtained on the catalyst to the weight of carbon subjected to methanation. There is 52 g H2 for nonpromoted Ru/Sibunit catalyst, 370 g H2 for the 0.5Ba–Ru/Sibunit sample, 200 g H2 for the 1.5Ba–Ru/Sibunit sample, and 150 g H2 for the 2.5Ba–Ru/Sibunit sample per 1 g of carbon loss.

The research data on the preparation of nickel catalysts obtained from modified carbon mineral materials based on sapropel are given. The nature of these materials and their modification method were shown to have effect on the textural and acid–base properties of the support, as well as on the properties of prepared catalysts in model hydrotransformations of 1-methylnaphthalene and dibenzothiophene. The highest increase in the catalytic activity was found to occur after acid pretreatment of sapropel-based carbon mineral materials due to the formation of acid sites on the support surface and finely dispersed particles of supported nickel.

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.

The structure, texture, and acid properties of platinum catalysts on oxide (Al2O3, ZrO2, ZrO2–Al2O3) and borate-containing supports (B2O3–Al2O3, B2O3–ZrO2) are studied. The catalysts are tested in the process of hydrocracking sunflower-seed oil at 380°C, 4.0 MPa, and a weight stock feed rate of 1.0 h–1. It has been found that aluminum oxide (A) contains the γ-Al2O3 phase, zirconium dioxide (Z) includes 85 and 15 rel. % of the monoclinic (M) and tetragonal (T) phases, respectively, while zirconium dioxide with the addition of 2.5 wt % Al2O3 (ZA) comprises 14 and 86 rel. % of the M–ZrO2 and T–ZrO2 phases, respectively. The B2O3–Al2O3 (BA) and B2O3–ZrO2 (BZ) systems modified with boron oxide (20 wt %) are X-ray amorphous. A Pt/BA catalyst differs from a Pt/A catalyst, while a Pt/BZ catalyst has a larger specific surface area and acidity than Pt/Z and Pt/ZA catalysts and contains Bronsted acidic centers (BACs) along with Lewis acidic centers (LACs). Only LACs are present on the surface of Pt/A, Pt/Z, and Pt/ZA catalysts. The LAC/BAC ratio in Pt/BA and Pt/BZ catalysts is 0.3 and 1.0, respectively. All the catalysts provide complete oil conversion to give C5+ hydrocarbons with a yield of 81.7–87.3 wt %. Pt/A catalyzes mainly decarboxylation and hydrogenation–dehydration reactions, while Pt/Z and Pt/ZA provide decarboxylation. The yield of diesel fraction reaches 71.8–73.9 wt % with an n-alkane content of 94.0–95.9 wt %. One-stage oil hydrocracking with the prevalence of hydrodecarbonylation and hydrogenation–dehydration reactions occurs on Pt/BA and Pt/BZ catalysts for 20 h to give the yield of the diesel fraction of at least 81.4 and 74.4 wt % and the total content of iso-alkanes and cycloalkanes of at least 28.3 and 60.7 wt %, respectively.

The effect of the mechanical activation of a mixture of MnCO3 · mMn(OH)2 · nH2O and AlOOH as a stage in the preparation of a MnO x -Al2O3 catalyst on the characteristics of the resulting samples was studied. It was found that the catalytic activity of MnO x -Al2O3 increased even after mechanical activation for 5 min. It was established that a decrease in the concentration of manganese hydroxocarbonate within the limits of the tested ratios between the components exerted the greatest positive effect of mechanical activation on catalytic activity. This was likely because the dispersion of this compound increased and interactions between the components strengthened in the course of mechanical activation. This was evidenced by a considerable increase in the amount of the α-Al2O3 phase relative to δ-Al2O3 in the catalyst calcined at 950°C. According to the results of temperature-programmed reduction with hydrogen, the formation of a larger number of catalytically active, fine MnO x particles after high-temperature heat treatment was responsible for the strengthening of interactions between the initial components upon mechanical activation. Transmission electron-microscopic data also indicated an increase in the dispersity of manganese oxide particles with the use of mechanical activation as a stage of the preparation of the MnO x -Al2O3 catalyst.

The carbon deposits forming upon the suboxidative pyrolysis of methane on resistive FeCrAl catalysts heated with electric current were studied. The suboxidative pyrolysis of methane was carried out in a flow reactor at the ratio CH4: O2 = 15: 1 in a catalyst-coil temperature range of 600–1200°C; a cold reaction mixture (∼20°C) was supplied. The morphology and structure of the carbon deposits and changes in the composition and structure of the catalyst were characterized by scanning electron microscopy, transmission electron microscopy with EDX analysis, Raman spectroscopy, and X-ray diffraction analysis. Various forms of carbon deposits, including branched nanotubes, and metal carbides formed by catalyst constituents were detected. It was found that the carbon deposits on the catalyst surface were morphologically different from the deposits on quartz reactor walls. The reasons for these differences were considered.

The precursors of massive Ni-Mo catalysts for hydrotreating processes, which were synthesized by the mechanochemical activation of a mixture of nickel hydroxocarbonate NiCO3·2Ni(OH)2·nH2O and ammonium paramolybdate (NH4)6Mo7O24 · 4H2O, were sulfidized. Their structure was studied by X-ray diffraction analysis and high-resolution electron microscopy. It was found that MoS2 packets, which are characterized by the presence of structural defects and geometric curvature, are the constituents of the massive catalysts. The catalyst also includes a phase of Ni3S2 and regions containing a complex Ni-Mo-S phase. The catalytic tests of the synthesized catalysts in the model reactions of 1-methylnaphthalene and dibenzothiophene conversions showed that the catalyst whose precursor was a heteropoly compound with the Anderson structure after the stage of mechanochemical activation exhibited the highest activity.

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 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.

The CuO-CeO2/Al2O3 catalysts for the selective oxidation of CO in hydrogen-containing mixtures were prepared by surface self-propagating thermal synthesis (SSTS) with the use of cerium nitrate Ce(NO3)3, the ammonia complex of copper acetate [Cu(NH3)4](CH3COO)2, and citric acid C6H8O7 as a fuel additive. The effect of the C6H8O7/Ce(NO3)3 molar ratio on the catalyst activity and selectivity for oxygen was studied. The catalyst samples were studied by X-ray diffraction (XRD) analysis, temperature-programmed reduction (TPR-H2), IR spectroscopy of adsorbed CO, and transmission electron microscopy (TEM). It was found that an increase in the C6H8O7/Ce(NO3)3 ratio resulted in an increase in the degree of dispersion of the resulting CeO2 phase. The greatest amount of dispersed CuO particles, which are responsible for catalytic activity in the oxidation of CO, was formed at C6H8O7/Ce(NO3)3 = 1.

The interaction between tert-butyl chloride and activated aluminum was studied by attenuated total reflectance Fourier transform infrared spectroscopy near room temperature (18–25°C). A long induction period of ∼240–260 min was observed. The ionic aluminum chloride complexes [Al n Cl3n+1]− (n = 1, 2) and the molecular species AlCl3 were identified at the activated aluminum/tert-butyl chloride interface during the reaction. The formation of the ion in the AlCl 4 − ion in the liquid medium and the presence of the same ion and a molecular AlCl3-tert-butyl chloride complex in the resinous products of the reaction were confirmed by 27Al NMR spectroscopy. The reaction products were analyzed qualitatively by GC/MS. The reactivities of activated aluminum and anhydrous aluminum chloride toward tert-butyl chloride under the same conditions were compared. A distinctive feature of the interaction activated aluminum and tert-butyl chloride is the dominant formation of the AlCl 4 − ion. By contrast, the interaction between aluminum chloride and tert-butyl chloride yields the polynuclear ion Al2Cl 7 − and, likely, Al3Cl 10 − .