Том 8, № 1 (2016)

Using a specially created experimental setup, the crossover character of a change in solubility is determined, and the approximate pressure at the upper crossover point is found (≈19 MPa). The modification of carbon dioxide with chloroform is shown to increase its solubility by 2–2.5 times on average within the above range of conditions. The supercritical CO₂ fluid extraction (SCFE) process is studied as it applies to the regeneration of LD-265 alumopalladium hydrogenation catalyst. Dimethylsulfoxide and ethanol are selected as cosolvents (modifiers). Maximum regeneration efficiency is established at a 5.5–6.5 wt % concentration of cosolvents, and dimethylsulfoxide proves to be a more efficient cosolvent than ethanol. The diene and bromine numbers and styrene and methylcyclopentadiene conversions obtained on catalysts regenerated via SCFE satisfy the requirements for catalytic systems used in the selective hydrogenation of dienes in a benzene–toluene–xylene fraction.

Kinetic characteristics of reactions occurring in the alkylation of phenol with straight-chain alkenes (C₉, C₁₆) over the Amberlyst 15 Dry, Amberlyst 35 Dry, Amberlyst 36 Dry, Amberlyst 70, Amberlyst DT, Tulsion 66 MP, Lewatit K2640, Lewatit K 2431, and Relite EXC8D sulfonic acid cation-exchange resins have been determined experimentally. The activities of these catalysts in different types of reactions have been compared. The rate constants of all reactions decrease on passing from 1-nonene to straight-chain hexadecene. In the alkylations of phenol with straight-chain alkenes, the ortho-alkylphenol/para-alkylphenol ratio is practically equal to the statistical ratio for all of the resins examined in their operation range.

Patent information on methods used for preparing catalytic systems containing molybdenum and tungsten phosphides and employing these systems in the hydroisomerization of paraffinic hydrocarbons are analyzed. Analysis of the patent information shows that modifying acidic supports with molybdenum and tungsten phosphides allows us to create a catalyst for the hydroisomerization of paraffinic fractions that is stable and resistant to sulfur impurities contained in the hydroisomerization feedstock.

Mathematical modeling is performed for the operation of two units of industrial chemical fluidized-bed reactors with different gas feedstock injection devices, i.e, three toroidal rings with nozzles in unit 1 and a false bottom with nozzles distributed over it in unit 2. Efficiency is analyzed (using the target product (iso-butylene) yield) for the operation of the two units over 4 months under industrial conditions and revealed the higher efficiency of unit 2. To dedetrmine the reasons for different product yields in the two units, a numerical solution is found by mathematical modeling to obtain characteristic pictures of catalyst particle concentrations and temperature fields in these units. It is concluded that unit 2 is characterized by a more uniform and dense distribution of the catalyst along with more uniform heating of the reactor. Pictures of the principal catalyst circulation flows are plotted to explain the considerable difference between the catalyst concentrations and gas temperature fields. Based on the numerical solution, the operational efficiency of the two units is subjected to comparative analysis, which showed good agreement with the results from an analysis of industrial reactors. The approach used in this work could be used in designing new units and optimizing existing units.

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 %.

The kinetics of the enzymatic hydrolysis of two substrates—lignocellulosic materials from Miscanthus and oat hulls—in an acetate buffer is studied at different concentrations of the substrates. The substrates are obtained via single-step treatment with a dilute solution of nitric acid. The content of a nonhydrolyzable component—acid-insoluble lignin—for Miscanthus and oat hulls was 11 and 14%, respectively. A multi-enzyme composition of commercially available enzyme preparations CelloLux-A and BrewZyme BGX was used as a catalyst. It is shown that treatment with the nitric acid solution produces reactive substrates for the enzymatic hydrolysis. The innovative science of the results is confirmed by Russian patent 2533921. Kinetics of the enzymatic hydrolysis of these substrates in an acetate buffer can be described by a mathematical model based on a modified Michaelis–Menten equation. The main kinetic constants for both substrates are determined from the experimental data. The equilibrium concentrations of reducing substances (RSes) for the substrates are calculated from the initial substrate concentrations. It is found that within the studied range of substrate concentrations (33.3–120.0 g/L), the initial rate of enzymatic hydrolysis for the lignocellulosic material from oat hulls is higher than that for the lignocellulosic material from Miscanthus by 1 g/(L h). It is shown that the yield of RS depends of the initial concentration of the substrates: as the concentration rises from 33.3 to 120 g/L, the yield of RS falls 1.5–2.0 times, due to substrate inhibition. At low initial concentrations, the yields of RS are similar for the substrates from Miscanthus and oat hulls. When the initial concentration of the substrate reaches 120 g/L, the yield of reducing substances for the lignocellulosic material from Miscanthus is approximately 20% higher than that for the lignocellulosic material from oat hulls. The established dependences and the proposed mathematical model allow us to optimize the initial concentration of the substrate for efficient enzymatic hydrolysis.

The efficiency of biocatalysts based on the cellulase complex from the Penicillium verruculosum fungus in the hydrolysis of kraft pulp from soft and hardwood is investigated. The activities of biocatalysts with respect to unbleached and bleached cellulose samples and the dependence of the degree of cellulose conversion on the content of noncellulose components are determined. It is shown that wet kraft pulp exhibits high reactivity in enzymatic hydrolysis with cellulase complex from P. verruculosum and is undoubtedly of interest as a substrate for scaling up biotechnological processes of the bioconversion of renewable plant-derived materials.