Vol 92, No 11 (2019)

The main achievements and procedures in the field of catalytic thermal processing of biomass are considered. Preparation of various valuable liquid products by catalytic biomass pyrolysis is described. The effect of various cations and anions on the yield of liquid and gaseous products of biomass pyrolysis is demonstrated. Catalytic treatment of biomass pyrolysis vapor allows improvement of the quality of liquid products. Modern procedures for catalytic biomass gasification to obtain syngas are analyzed. Production of resin-free syngas requires additional treatment steps. Problems of using catalysts in thermal biomass processing are discussed.

The fractional and chemical composition of bio-oil and its gasoline fraction, obtained by hydrothermal liquefaction of Arthrospira platensis biomass, was studied. The bio-oil yield was 34.6%, the heat of combustion of bio-oil was 33.4 MJ kg-1, and the gasoline fraction yield was 28.8%. The content of carbon and hydrogen in the gasoline fraction of the bio-oil is appreciably higher than in the initial bio-oil, and the calorific value of the gasoline fraction is 3.87 MJ kg-1 higher than that of the initial bio-oil. With respect to the carbon and hydrogen content, the gasoline fraction of the bio-oil is close to motor fuels, differing from them in the higher content of nitrogen, oxygen, and sulfur. Fractional distillation of bio-oil decreases the content of high-molecular-mass condensed compounds in the product.

Microfibrous materials with the average fiber diameter of 7 μm, surface density of 80-100 g m^-2, and packing density of 5-7% were prepared with a high-performance single-nozzle setup (polymer melt feeding rate ~70 mL h^-1). The electrospinning is accompanied by a change in the supramolecular structure of the polylactide: Whereas the initial granular polymer contains thermodynamically stable crystals of α-form, the nonwoven materials are amorphous, which is caused by high rate of the polymer cooling under the conditions of drawing in a strong electric field. Annealing of the fibrous materials restores the crystalline phase, and its fraction increases with the annealing time. The maximal sorption capacity of the microfibrous matrices obtained for motor oil is 85 g g^-1.

Specific features of the interaction of granulated polyvinyl chloride with polyethylenepolyamine were examined. It was shown that, to perform the reaction, it is necessary to make the granules porous by removing from the plastic compound the plasticizer and other additives introduced into the plastic compound when granules are formed. It was found that the reaction is to be performed in two stages: to treat the plastic compound with polyethylenepolyamine, with the subsequent ripening of the product at temperatures of 423 K and above. The modification yielded an anion exchanger with properties that compare well with AH-31 industrial anion exchanger. Tests performed at MAXAM-CHIRCHIQ JSC made it possible to recommend the anion exchanger synthesized in the study for use in industrial water treatment.

A new method for producing oxidized starches using hydrogen peroxide and thiourea dioxide is proposed. It is shown that this method makes it possible to broadly control the number of functional groups arising in modified starch as well as the viscosity of the paste made from modified starch. This is achieved by changing the molar ratio of thiourea dioxide and hydrogen peroxide. The oxidative modification of starch is carried out under mild conditions and proceeds at high speed.

The results of studying the anodic behavior of Zn5Al, Zn55Al alloys doped with nickel in a NaCl electrolyte are presented. It was found that nickel additives in an amount of 0.01-0.5 wt % contribute to a decrease in the anodic corrosion rate of the initial Zn5Al and Zn55Al alloys by approximately 15-20%. It is shown that alloying the initial alloys with nickel shifts the potentials of free corrosion, pitting and repassivation to the positive region. The proposed compositions of zinc-aluminum alloys containing nickel can be used as an anode coating for corrosion protection of metal structures for various purposes, including steel structures and structures.

p-tert-Butyphenol is a valuable product of basic organic synthesis, widely used in various branches of industry. The relationships of acid decomposition of p-tert-butylcumene hydroperoxide to p-tert-butylphenol and acetone as one of the key steps of the alternative method for p-tert-butylphenol synthesis were studied. The influence exerted by temperature, catalyst concentration, and initial concentration of p-tert-butylcumene hydroperoxide on its acid decomposition was examined. Conditions ensuring preparation of p-tert-butylphenol in 92% yield were found. A kinetic model of the acid decomposition of p-tert-butylcumene hydroperoxide in the presence of concentrated sulfuric acid was constructed; it adequately describes the experimental data and allows substantiation of the reaction mechanism.

Naphtha fractions of the West Siberian gas condensate were evaluated as feedstock for thermal pyrolysis performed in the temperature interval 750–900°C at the conventional contact time of 0.2–0.4 s and steam-to-feed weight ratio of (0.5; 0.8): 1.0. Statistical models of the process, based on the experimental dataset obtained, were constructed and used for multicriteria optimization with respect to the key products: ethylene, propylene, divinyl, pyrogas, and coke. The optimum process parameters for pyrolysis of light and heavy naphtha of the gas condensate to reach the maximal yield of target products (ethylene, propylene, divinyl) under the conditions of compromise solutions were found. The influence of the group and individual hydrocarbon composition of the naphtha fractions of the gas condensate on the yield and distribution of the major products was demonstrated.

Kinetic regularities of the mass loss and heat and-gas release were studied in the thermal decomposition of a solid propellant composed of aluminum, ammonium perchlorate, and a polymer binder. It was shown that, under heating from 40 to 340°C under permanent vacuum conditions, propellant samples decompose without ignition, with the limiting mass loss in the decomposition being 48%. When experiments were performed in air, the propellant formulation decomposes with sharp ignition, with the inflammation temperature (270–287°C) and amount of volatiles released by this instant of time (10–16 wt %) dependent on the heating rate. The kinetic regularities of the mass loss in the decomposition of a solid propellant were described in terms of the polychromatic kinetics model that assumes that the reaction system has ensembles of particles differing in reactivity. The distribution functions of the mass fractions of the propellant by activation energies of decomposition were calculated. The heat release kinetics in the decomposition of a propellant formulation in the temperature range 153–270°C in a closed evacuated system is described by a sum of equations for two parallel reactions: 1st-order reaction with a heat effect Q₁ = 200 ± 5 kJ kg^–1 and 1st-order autocatalysis with heat effect Q₂ = 1900 ± 50 kJ kg–1. The rate constants and the activation parameters of the process were determined.

Ultrafiltration membranes based on aromatic copolyamide, comprising 10% of units with sulfonate groups were produced. The possibility of their use as a matrix for the immobilization of ligands used in affinity chromatography: metal cations, amino acids, and dyes, is shown. The components of immobilization were copper(II) ions, histidine, lysine, and 3,6-diamino-10-methylacridine chloride. It was found that immobilization mainly occurs due to the electrostatic interaction of the corresponding functional groups of the component and copolyamide and is not accompanied by a decrease in the specific membrane productivity in water. The investigations of adsorption (under static conditions and ultrafiltration of protein solutions) were performed as well as mass transfer properties of modified membranes. The nature of the effect of the modification was revealed on the mass transfer characteristics of the obtained materials. For an unmodified membrane, the optimal combination of selectivity and specific productivity was realized at pH of the protein solution above its isoelectric point. Depending on the nature of the immobilized component, selectivity of 0.96–0.99 can be achieved at the pH below or equal to the isoelectric point of the protein.

Possibility of using polydecylmethylsiloxane in the pervaporation removal of organic compounds from aqueous media was examined. It was shown for the example of the system with 1 wt % n-butanol in water that this material is characterized by a large separation factor (69), which twice exceeds the separation factor of the commercial membrane polymer polydimethylsiloxane. A composite membrane was produced on the basis of polydecylmethylsiloxane. The selective layer was deposited from a solution of the polymer by the touching method onto an MFFK-1 domestic microfiltration substrate. Pervaporation experiments with the new composite membranes based on polydecylmethylsiloxane were used to determine the optimal separation mode of the water–butanol mixture: delivery rate of the mixture to be separated, 1.2 cm s–₁; and separation temperature 40°C. It was shown that, at a selective layer thickness of about 4.5 μm, it is possible to reach a permeability of the PDecMS/ MFFK-1 membrane that is comparable with the permeability for 1-butanol of commercial composite membranes (5.2 mol m–₂ h kPa_–1). However, the butanol/water selectivity for the PDecMS/MFFK-1 membrane is 3–7 times that of the commercial membranes.