Valery Tarabanko

Russian Academy of Sciences | RAS · ICCT CB RAS

The influence of mass transfer intensity on the kinetics of the catalytic oxidation of flax shives with oxygen in alkaline media to aromatic aldehydes and pulp was studied. The process was carried out in two autoclaves, with moderate stirring (stirrer engine of 8 W) and intense stirring (stirrer engine of 200 W). The oxidation of flax shives into v...

The reductive catalytic fractionation of flax shives in the presence of bimetallic NiRu catalysts supported on oxidized carbon materials (CM) such as mesoporous Sibunit and carbon mesostructured by KAIST (CMK-3) was studied. The catalysts based on CMK-3 were characterized by a higher surface area (1216 m2/g) compared to the ones based on Sibunit (3...

Hydrogenation of flax shives in ethanol over bifunctional Ni/C catalysts at 225 °C has been studied. It has been shown that the 10% Ni/C catalyst enhances the yield of monomeric products from 1.1 to 9.7 wt %, decreases the solid product content from 45 to 35 wt %, and increases the degree of delignification to 91%. The main monomeric compounds obta...

This research deals with a process of catalytic oxidation of flax shives to vanillin and pulp. Catalytic oxidation of flax shives with molecular oxygen allows two main products to be obtained—vanillin with a yield of up to 12 wt.% of lignin, and pulp. Final forms of the catalyst particles (Cu2O and CuO) are agglomerates or monocrystals 0.5–5 µm in...

The literature on the existing processes for the synthesis of γ-acetopropyl alcohol (acetopropanol, 5-hydroxypentan-2-one, APA) is reviewed. This substance is used to produce vitamin B1, antimalarial drugs and polymers. The promising methods for APA production are the hydrogenation-hydration of sylvan (2-methylfuran), hydrogenation of furfural, and...

The influence of mass transfer intensity on kinetics of catalytic oxidation of flax shives with oxygen to aromatic aldehydes and pulp was studied. The process was carried out in an autoclave in an aqueous-alkaline medium in the presence of CuO as the catalyst. Oxidation of flax shives into vanillin, syringaldehyde, and pulp was shown to proceed as...

Double activation catalysis was experimentally observed in hydrolysis of cellobiose catalyzed simultaneously with phthalic and hydrochloric acids, confirming earlier theoretical prediction known from literature. Both acids can catalyze the reaction individually, and contribution of the double‐activation pathway to the total reaction rate declines a...

The catalytic oxidation of natural and pre-extracted cedar bark (Pinus Sibirica) by molecular oxygen is studied. Tannins were shown to inhibit the formation of vanillin while oxidizing the bark. The yields of vanillin are 5–7 wt.% based on bark lignin, which is of 3–4 times lower compared to the results of wood oxidation. The presence of tannins in...

Modern civilization is moving from fossil sources of raw materials and, consequently, energy to renewable resources: plant raw materials and solar and wind energy [...]

The process of catalytic hydrogenation of furfural diethyl acetal to ethyl furfuryl ether on the different catalysts (palladium, palladium-rhenium and copper-ruthenium on Sibunit in reduced forms) was studied. It was found that hydrogenation of the furan ring with the formation of THF diethyl acetal occurs on all the catalysts. Ethyl furfuryl ether...

Thermal conversion of flax shives was studied in sub- and supercritical ethanol medium at 225 and 250 °C in the presence of the bifunctional catalyst 3% Ru/C. The use of 3% Ru/C catalyst in the process of thermal conversion of flax shives in supercritical ethanol was found to increase the conversion of the shives by 27% and the yield of liquid prod...

Flax shive is the main waste (up to 70 wt %) in the production of flax fiber. It represents the lignified parts of the flax stem mainly in the form of small straws. Complex processing of such wastes is a significant problem due to the heterogeneity of the chemical structure of lignin. This article presents the results of reductive catalytic fractio...

The divanillin synthesis by oxidative dimerization of vanillin in the presence of juice and water extracts of horseradish root (Armorácia rusticána), a more available and cheaper catalyst as compared with horseradish reactive peroxidase (HRP) was studied. The divanillin yield exceeds 90 mol. % based on loaded vanillin. The peroxidase activity in ju...

The influence of pine wood (Pinus Sylvestris) prehydrolysis on the consumption of main reagents (O2 and NaOH) in the subsequent catalyzed oxidation of the obtained lignocelluloses into vanillin and pulp has been studied. Prehydrolysis of the feedstock was performed with HCl in the water and gas phases. Catalytic oxidation was performed in an autocl...

Dear Colleagues, Replacement of fossil carbon sources for chemical industry in favor of renewable plant feedstocks keeps attracting increasing interest from research and industry. Wood and agricultural wastes contains three principal polymer components—lignin, cellulose, and hemicelluloses—that can be processed into biofuels, novel polymers, specia...

In this paper we continue working on our theory of electrical double layers resulting exclusively from dissociation of a solid electrolyte, which we previously proposed as a medium for catalytic interaction between solid cellulose and solid acid catalysts of hydrolysis. Two theoretical unidimensional models of the inner grain volume are considered:...

Two alternative routes of softwood catalytic oxidative fractionation to cellulose products and fine chemicals are assessed. Wesuggested to use the process of larch wood peroxide oxidation in the medium acetic acid – water at temperatures 70–100 °C in the presence of soluble catalyst (NH4)6Mo7O24 to produce microcrystalline cellulose (35.0 wt% on wo...

In the present work, a kinetic study and optimization of the process of spruce wood peroxide oxidation in “acetic acid–water” medium in the presence of suspended TiO2 catalyst at temperatures 70–100 °C were accomplished for the first time. The effect of wood species and organic solvent nature on the features of the processes of catalytic peroxide f...

Copolymers and block-copolymers of ε-caprolactam, α-angelicalactone and polyangelicalactone were first synthesized by the anionic polymerization method. Yields of polymers and rates of their formation decrease with increasing the α-angelicalactone and polyangelicalactone concentration. Physical and mechanical properties of the obtained copolymers a...

For the first time emulsion polymerization of polyangelicalactone with styrene was carried out. Block copolymers with a molecular weight of 40000-1000000 and containing 5-40 wt. % of styrene were prepared. Polymerization rate constants were evaluated. Mechanical properties were evaluated after the copolymers were cured. The cured block copolymers s...

Solid acid catalysts of cellulose hydrolysis in aqueous media attract considerable research interest because of the ease of their separation from the reaction products. The nature of interaction between the two solids is a relevant topic of ongoing research. One aspect of behavior of solid acids in water was not previously discussed in literature w...

The kinetics of oxidation of the enzymatic lignin from pine wood (brown rotted wood) by oxygen in an aqueous alkaline medium at 90–160°C was investigated. It was established that the vanillin yield increased gradually with the temperature increase in this range from 3.4 to 5.6 wt % with respect to lignin. The observed activation energy of the proce...

The processes of palladium deposition on various high-porosity carbon matrices (Sibunit, CMK-3) have been studied. Mesostructured carbon material CMK-3 was synthesized using a silicate template of SBA-15 type. Pd nanoparticles were loaded onto carbon matrices by metalorganic chemical vapour deposition (MOCVD) method using palladium(II) acetylaceton...

Thermodynamics of sodium butoxide-catalyzed polymerization of α-angelicalactone (a five-member unsaturated lactone) is studied by calorimetric methods. A polymer with Mw = 2,500 g/mol and the ratio of C–O to C–C inter-monomeric bonds 87–13% is obtained; this polymerization is characterized by the values of ΔHpol∘ = −33.41 kJ/mol, ΔSpol∘ = −42.69 J/...

This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the pr...

Extractive-free pine wood was processed into vanillin (up to 18 wt.% of the initial lignin) and cellulose (typically 84–93% of the initial amount in the wood) by one-step catalytic oxidation followed by enzymatic hydrolysis of the resulting cellulose into glucose (reducing sugar yield up to 70% based on the post-oxidation cellulose). Correlation be...

The processes of furfural hydrogenation in the alcohol solutions over copper-ruthenium and platinum catalysts were studied. The equilibrium of acetals formation is shown to establish in the solutions. Both substances, furfural and the acetals of furfural are hydrogenated in the system. The acetals hydrogenation produces alkylfurfuryl ethers, and se...

Preparative amounts of furfuryl alcohol ethers and furfural acetals were prepared from renewable vegetable raw materials. The blending reseach octane numbers of mixing of furan derivatives in straight-run gasoline were estimated: butyl furfuryl ether, 97.8 ± 7; propyl furfuryl ether, 112 ± 6; furfural diethyl acetal, 105 ± 6, furfural ethylene glyc...

Novel biodegradable polymer materials have been synthesised via copolymerization of styrene, or caprolactam, or ethyleneterephthalate oligomers, or methylmethacrylate with comparatively small amounts (1–20 mol. %) of α-angelicalactone (AL) or polyangelicalactone (PAL). The molecular mass (up to 150000 amu), tensile strength (up to 170 MPa for ethyl...

The capabilities of crystallization and extraction methods for separation of vanillin and syringaldehyde are described. Crystallization methods are based on differences in solubility of aldehydes ammonia derivatives in water, and solubility of their potassium salts in concentrated aqueous solutions of potassium carbonate. Temperature dependencies o...

Regeneration of chlorine by oxidation of hydrogen chloride is an important problem in the production of chloroorganic products. The known catalysts for this reaction are insufficiently active and typically not stable enough, while data on the use of V catalysts for this process are absent. Here we report on our study of the stability and catalytic...

Composition and content of terpene compounds in pine bark (Pinus sylvestris) after various storage periods were studied by GLC-MS. Resin acids were found to be the main diterpenoic compounds in the bark. Content of dehydroabietic acid in initial bark is 0.6 g/kg and it decreases three-fold after one year of storage. High activity of pine bark after...

The extraction of vanillin (4‐hydroxy‐3‐methoxybenzaldehyde) from water medium with octylamine solution in heptane was studied. The distribution ratios were found to increase with the octylamine concentration and to attain values up to 600. The slope of the logarithmic dependence of the distribution ratios versus octylamine concentration is equal t...

A flow reactor was used to study the kinetics of 5-hydroxymethylfurfural synthesis from fructose and sucrose at 240 o C in water solutions containing acetic and phosphoric acid as catalysts. The maximum yield of 5-hydroxymethylfurfural was found to be practically independent of the chosen catalyst and carbohydrate. It attained 40 mol. % at 240–250...

The previously proposed mechanism for lignin oxidation to vanillin was supported experimentally. This process begins with the formation of a phenoxyl radical and ends with the step of retroaldol cleavage of substituted coniferaldehyde to vanillin. The oxidation of model compounds was studied, and experimental evidence for the proposed mechanism was...

A conception about the mechanism of fullerene formation in carbon plasma is developed based on the influence of electron concentration on the stability of carbon clusters. Thermodynamic estimates for the efficiency of formation of spheroidal, flat clusters and linear carbon chains depending on the charge of the reacting particles are described. Str...

The kinetic curves of levulinic acid accumulation in the process of saccharide dehydration at 80-98oC are compared. The structural features of the substrates and 5-hydroxymethylfurfural, which is the intermediate of the process, explain the observed difference in the rates of fructose and glucose conversion. Sulfuric acid can be effectively used un...

The kinetics of aspen wood oxidation has been studied using the method of initial rates of oxygen consumption. Under certain conditions, the mass transfer processes practically did not limit the process rate. The reaction orders with respect to oxygen and hydroxide anion were determined experimentally. They depend on the conditions of the reaction,...

Kinetics and selectivity of the retroaldol reaction of vanillideneacetone in the alkaline media were studied. The reaction is of first order with respect to substrate and alkali concentration. The pH dependencies of the rates of vanillin formation in the processes of lignosulfonates and vanillideneacetone oxidation agree almost quantitatively. This...

The influence of catalyst (CuSO4 solution), pH and temperature on the vanillin formation and oxygen consumption in oxidation of lignin in alkaline media have been studied. It was shown that the main role of catalyst in the lignin oxidation is to change the selectivity of hydroperoxide fragmentation rather than to accelerate oxidation.

The action of methanol in the liquefaction of Kansk-Achinsk lignite in the presence of H2 has been studied. Hydroxides and chlorides of Ni, Co, Zn, Cr, Sn, Fe and Mo were used as catalysts. The most active catalysts were Ni and Co hydroxides. The use of methanol did not result in an increase in coal conversion but improved significantly the quality...

It has been established that the catalytic effect of Zn−Cr catalysts on coal liquefaction in methanol is due to the hydrogenation of coal and its liquefaction products by dihydrogen. The latter is formed by catalytic decomposition of methanol. Impregnated catalysts are more active than unsupported ones. Quantitative processing of PMR data indicated...

It has been established that in the oxidation of diethyl sulfide by18O2 in CH3C16O2H−H216O solution at 369 K catalyzed by heteropoly acids, sulfoxide and sulfone with 44–54%18O enrichment are formed. The process is accompanied by isotope exchange of molecular oxygen.

Oxidative coupling of thiophene and 2-methylfuran to the corresponding dihetaryls in DMFA medium occurs in the presence of the homogeneous catalytic system Pd(II)-molybdovanodophosphoric heteropolyacid (HPA). The data obtained show that HPA may act as a reversible oxidant in polar aprotic media.

The new regenerable catalyst H 2 SO 4 + Na 2 SO 4 for the levulinic acid production has been developed. The catalyst provides product extraction from the reaction mass with n-butanol during the reaction. The acid-catalyzed dehydration process of fructose and sucrose in three systems (homogeneous water solution, homogeneous butanol solution and two-...