The alkaline oxidation of pine wood powder (Pinus sylvestris) by oxygen to produce vanillin and cellulose has been studied. The influence of temperature and catalyst (CuO) on the yield of vanillin, other monophenols and lignocellulosic residue (LCR) has been studied over a wide temperature range (120-220 °C). The highest vanillin yield obtained (49 wt.%) surpasses previously reported values. This can be attributed to the high oxidation rate, intense mass transfer, and optimal temperature conditions (12-15 minutes; stirring speed 1200 rpm; 180 °C). Within the temperature range of 120-180 °C, the use of a catalyst slightly increased the maximum vanillin yield (approximately 10% relative). The cellulose yield in the process attained 28-45% based on its initial content in wood. The highest vanillin yield was attained under harder conditions compared to those for cellulose production. Catalyst use accelerated the process, but this effect decreased to zero as temperature increased to 160 °C. The decrease in apperent activation energy as temperature increases can be explained by the transition of the process from a kinetic mode at lower temperatures (120-140 °C) to a diffusion-controlled regime under the conditions of maximum vanillin yield. The structure of native lignin in softwood is discussed.

The growth-promoting activity of lignoacids (LA), byproducts of the catalytic oxidation of pine and aspen wood to vanillin and cellulose, was studied. The use of LA opens the possibility of recycling wastewater from the catalytic processing of wood. The growth-promoting activity of LA was assessed on radish seeds Raphanus sativus var. radicula under laboratory conditions during germination on filter paper; germination energy, germination rate, and root and hypocotyl lengths were determined. The growth-promoting activity of LA was compared to radish seed germination in water and potassium bicarbonate solutions. It was shown that LA isolated during pine wood oxidation at concentrations of 5–40 mg/L exhibited a more pronounced growth-promoting effect compared to lignoacids isolated from aspen wood oxidation reaction solutions. It has been established that the growth-promoting effect increases in the order LCOsins < Pine LKS < Flax shives. This corresponds to a decrease in the content of methoxyl groups in various lignins. Lignoacids released during the oxidation of lignins from herbaceous plants and agricultural waste appear more promising for use as growth stimulants.

Electrokinetic potential (zeta, ζ) of two strong insoluble Brønsted acids (Cs2.5H0.5PW12O40 and sulfonated carbon) was measured in water in the presence of small electrically neutral molecules (ethyl acetate, cellobiose). The strongly negative ζ potential, which originates from the dissociation of surface acid sites, is altered when adsorption of neutral species occurs. Superacidic Cs2.5H0.5PW12O40 showed strengthening of ζ when adsorbing hydrophobic substance (ester); together with the adsorption isotherm showing capillary condensation, this suggests displacement of hydrated protons from pores toward the outer particle surface, leading to a denser proton diffuse layer. A connection of this fact is established with the high catalytic activity of the solid polyoxometalate in comparison with homogeneous catalysis (based on literature data). Nonsuperacidic sulfonated carbon showed weakening of ζ upon adsorption of both hydrophobic and hydrophilic compounds, which suggests suppression of dissociation of the sulfonic groups. Poisoning of sulfonated carbons by dissociation-suppressing adsorbed intermediates is demonstrated in the hydrolysis of cellulose (based on literature data). The obtained results suggest a strong involvement of the diffuse layer of solid acids in acid-catalyzed reactions, as well as showing the importance of considering the influence of reactant adsorption on the double-layer configuration of solid acid catalysts.

The reductive catalytic fractionation of agricultural waste-buckwheat husks, sunflower husks, and flax shivesusing a NiRu/C bimetallic catalyst was studied. Based on the following parameters: maximum yield of monomeric phenols (18.6 % based on lignin), individual substance (guaiacyl propanol, 13 % based on lignin), cellulose (27 % based on initial content), and degree of delignification (77 %), flax shives are the most suitable substances among the studied species for current research and industrial applications. Another advantage of flax shives is the high content of guaiacyl propanol in the monophenols obtained (two-thirds). This dominance is due to the isolation and purification of guaiacyl propanol as an individual compound in the process product-a byproduct of the agricultural waste recycling process.

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 a completely diffusion-controlled process under the studied conditions. Depending on the process conditions, it can be limited by stages of oxygen transfer through the gas–liquid interface as well as by oxygen transfer through the bulk of a Newtonian liquid phase and non-Newtonian suspension of the reaction mass. The results obtained on the influence of stirring speed and volume of the reaction mass on the rates of oxygen consumption and vanillin accumulation were described by a simple well-known model connecting the intensity of mass transfer and the stirring power density in the bulk of the liquid phase. It was shown that, despite the distinctly diffusion-controlled conditions of flax shives oxidation with oxygen, the vanillin yield was very close (70–83

Nanoscale nickel particles formed in situ using nickel formate as a precursor are proposed for the reductive catalytic fractionation (RCF) of flax shives. The examination of solid products of flax shives RCF by XRD revealed that characteristic reflections for Ni0 (111), (200), (220) at 2θ angles of 44, 52, and 76, respectively, are present in the X-ray diffraction patterns, hinting at the metal in situ reduction. The presence of Ni oxides was also confirmed via XPS (signals 855.8 and 874.3 eV, Ni0/Niox = 0.0). The alternative Ni-catalyst was pre-deposited on flax shives via reduction of nickel formate by hydrazine. The pre-deposited Ni particles were found to be XRD amorphous hinting at fine distribution and XPS confirmed both metallic and oxidized states Ni0, Ni2+, Ni3+ at the surface (Ni0/Niox = 0.14). Monomeric compounds, such as 4-propylguaiacol, 4-propenylguaiacol, and 4-propanolguaiacol, were obtained with a total yield of 6.92 wt.

Agrotechnical wastes from processing herbaceous plants consist of lignin and polysaccharides, which can be processed into monomers – phenols and carbohydrates. The prospects of chemical processing of several agrotechnical waste types with a high lignin content (flax shives, sunflower seed husks and buckwheat husks) into vanillin, pulp, and glucose by oxidation and acid hydrolysis were studied. It has been shown that despite the distant phylogenetic relationship of the studied plants, their lignins have a similar structure: they contain a similar amount of methoxyl groups (10–13 wt.% per lignin) and give close yields of aromatic aldehydes upon oxidation with nitrobenzene (17–19%) and oxygen (14–16%). In general, the suitability of agrotechnical wastes for oxidation to aromatic aldehydes determines by the lignin content. Among the studied wastes, flax shives are the most promising feedstock for chemical processing into vanillin and glucose. Cellulose-containing solid residues of oxidation process are more easily hydrolyzed compared to the initial lignocellulosic biomass. The inversion of glucose oligomers during the hydrolysis of cellulose with H2SO4 is limited by the hydrolysis of the tetra- and octamers.

Biodegradation ability of synthetic polymer materials is an urgent problem of modern ecology situation. A known new biodegradable polymer is polyangelicalactone (PAL). In this paper, styrene- a-angelicalactone copolymers were obtained by radical polymerization. The resulting copolymers have physical and mechanical properties similar to those of polystyrene and its graft-copolymers with PAL. Both they were mechanically destroyed when incubated in gray forest soil over 28 weeks. The obtained results show that the modification of polystyrene with the impurities of a-angelicalactone does not worsen the mechanical properties of the copolymers but instead gives them biodegradation abilities.

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 vanillin, syringaldehyde, and pulp was shown to proceed as a completely diffusion-controlled process under the studied conditions, both moderate and intense stirring. Depending on the process conditions, it can be limited by stages of oxygen transfer through the diffusion boundary layer near the gas–liquid interface (low intensity of mass transfer) as well as by reagents’ inner diffusion in the porous and solid matter of the flax shive particle (high intensity of mass transfer). The results on the influence of the stirring speed and volume of the reaction mass on the rates of oxygen consumption and vanillin accumulation were obtained. They were described using a known simple model connecting the intensity of mass transfer and the stirring power density in the bulk of the liquid phase in terms of algebra equations.

Biodegradable and biocompatible polyesters, obtained from renewable plant materials, are of great interest due to their use in various industries. The kinetics of anionic ring- opening polymerization (ROP) of alpha- angelicalactone (alpha AL) initiated by sodium alcoxides and aluminum isopropoxide has been studied. The kinetics of the process is described by the first order equation in terms of alpha AL concentration. An increase of the initiator concentration increases the first order rate constant and the alpha AL conversion, but reduces the molecular weight of the resulting polymers. The maximum alpha AL conversions (>= 0.99) and molecular weights of polymers (26000-29000) were obtained in non- polar solvents, toluene and carbon tetrachloride, and in the bulk at 373-403 K for 60-250 hours.

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 (315 m2/g). The catalyst supported on CMK-3 (10Ni3RuC400) was characterized by a more uniform distribution of Ni particles, in contrast to the Sibunit-based catalyst (10Ni3RuS450), on the surface of which large agglomerated particles (300–400 nm) were presented. The bimetallic catalysts were found to be more selective towards propanol-substituted methoxyphenols compared to monometallic Ru/C and Ni/C catalysts. A high yield of monomers (up to 26 wt%, including 17% 4-propanol guaiacol) was obtained in the presence of a 10Ni3RuC400 catalyst based on CMK-3.

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 syntheses based on allyl acetate, sodium acetoacetic ether, and γ-butyrolactone.

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 size. Acid prehydrolysis of the shives does not affect the oxidation, in contrast to pine-wood oxidation. Lignin prehydrolysis and oxidation was suggested as illustrate this difference. The dependence of the vanillin formation rate on stirring speed was studied. Minimum alkali consumption in the process was attained with a mild stirring speed of the reaction mass.

Polyangelicalactone-graft-polystyrene copolymers were obtained through cationic polymerization. Increasing the portion of styrene units in the copolymers improves the strength properties and increases fragility. Increasing the polyangelicalactone(PAL) content in the copolymers increases the elasticity of the materials obtained. The obtained copolymers are greatly a composition of PAL and polystyrene (PS)with a small content of bonds of styrene-units of 4-alkoxypent‑3-enoic acid.Low α-angelicalactone(AL) content in styrene copolymers improves the oxidative stability of the copolymers. The resulting PAL‑graft-PScopolymers have physical and mechanical properties corresponding to the requirements for general-purpose PS

Polyangelicalactone-graft-polystyrene copoly mers (PAL-graft-PS) were obtained through cationic polymerization. The resulting copolymers were completely destroyed when incubated in gray forest soil over 28 weeks. Individual strains of fungi destroyed the copolymer partially within 13 weeks; the most active among the studied cultures was Leptographium sp. The biodegradation products of copolymers do not statistically have a toxic effect. The obtained results show that the modification of polystyrene (PS) with the impurities of polyangelicalactone (PAL) gives them biodegradation abilities and does not worsen the properties of the copolymers.

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 obtained during hydrogenation are propyl guaiacol and propenyl guaiacol. It has been established that an increase in the mass transfer intensity via increasing the stirring rate or decreasing the catalyst grain size leads to an increase in the total yield of monomeric compounds and the propanol guaiacol yield. Alkaline and acid pretreatment increases the cellulose content in the solid product from 42 to 73 wt %. The proposed sequential scheme of the transformation and formation of monomeric products over the bifunctional nickel catalyst is lignin—coniferyl alcohol—4-propanol guaiacol—4-propenyl guaiacol—4-propyl guaiacol.

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 as temperature increases. In fact, above a certain temperature, the hydrolysis rate in presence of both acids becomes lower than the sum of the rates for the two acids acting individually. A kinetic model is proposed to explain this transition between double-activated catalysis and inhibition. The trend of declining contribution of cooperative catalytic pathway with rising temperature is theorized to be generally applicable for any reaction with a pathway involving simultaneous action of two catalysts when either of them can individually catalyze the reaction.

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 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 the raw material complicates the lignin analysis and can overestimate the results twice

A novel screw-type reactor for the fast pyrolysis of agricultural waste (flax shive) is described. A preliminary study on the influence of process parameters on the yield, composition, and properties of pyrolysis products was carried out. Based on the results obtained, the optimal conditions of fast pyrolysis of flax shive particles in terms of feedstock particle size, solid residence time, and process temperature were identified. Considering the construction, the developed reactor seems to be close to the screw fluidized bed and auger reactor and is characterized by a simple design and operation control. Moreover, the proposed reactor can be used for continuous pyrolysis without any significant modification.