Boris N. Kuznetsov

On the mechanism of vanillin formation in the catalytic oxidation of lignin with oxygen

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.

Influence of lignin origin on the efficiency of the catalytic oxidation of lignin into vanillin and syringaldehyde

The oxidation of a number of lignin species by molecular oxygen was studied. The selectivity of the process was found to be close to that of the oxidation with nitrobenzene. The influence of lignin origin on the yields of vanillin and syringaldehyde as well as the correlation between the rates of wood delignification and the aldehydes formation are discussed.

Highly mesoporous organic aerogels derived from soy and tannin

The first organic aerogels natural at the 91% level, based on soy and tannin, are reported. Such materials were prepared from denatured soy protein which was formylated, crosslinked with flavonoid tannin at different pHs, gelled and cured at 85 °C, and finally dried with supercritical CO2. The resultant aerogels presented both low bulk density and high mesopore volumes. Morphology, pore texture, chemical structure and thermal performances have been investigated by SEM, envelope and helium pycnometry, nitrogen adsorption at 77 K, FTIR, elemental analysis, XPS, NMR and hot disk transient plane source methods, respectively. We show that soy–tannin aerogels are among the “greenest” organic aerogels combining low cost, renewable character, highly developed mesopore texture and good thermal performances.

New catalytic methods for obtaining cellulose and other chemical products from vegetable biomass

Experimental data concerning the effects of catalysts are discussed for the oxidative destruction of wood lignin in the acetic acid-hydrogen peroxide-water medium, for lignin oxidation with oxygen into aromatic aldehydes in aqueous alkali, for the acid-catalyzed conversion of carbohydrates into esters of levulinic acid and 5-hydroxymethylfurfural in the two-phase system butanol-water, and for α-angelicalactone polymerization into biodegradable polymers.

Modification of iron ore catalysts for lignite hydrogenation and hydrocracking of coal-derived liquids

The activity of haematite, magnetite, pyrite and pyrrhotite containing ore catalysts, modified by treatment in a tensile-energy planetary activator mill and by elemental sulphur additions, has been studied in lignite hydrogenation and coal-derived liquid hydrocracking processes. The application of modified ore catalysts resulted in a significant (by two to four times) increasing of lignite conversion degree and in higher yields of distillate fractions, obtained by hydrocracking of heavy coal-liquids. Mechanical activation of iron ore catalysts in the presence of elemental sulphur increased their surface area and promoted the formation during hydrogenation process at dispersed pyrrhotite particles with high catalytic activity.

The use of non-isobaric pre-hydrolysis for the isolation of organic compounds from wood and bark

Abstract The effect of non-isobaric short-time pre-hydrolysis of Siberian type wood and wood bark (Populus tremula wood, Larix sibirica bark, Abies sibirica bark) on the isolation of different organic substances was studied. From Populus tremula wood, activated at 187–240°C and 1.2–3.4 MPa, cellulose and sugar solution were isolated with yields up to 50 wt%, and 11 wt%, respectively. The composition of water-soluble compounds was studied by chemical and chromatographic methods. The main compounds were represented by mono- and oligo-saccharides, low molecular mass lignin, acetic acid, furfural and other products of sugar destruction. Methanol, isopropanol, propionic acid and hydroxymethylfurfural were formed in small amounts. The non-isobaric pre-hydrolysis of coniferous bark promoted the extraction process and increased the yield of extracted compounds. Some information on functional composition of extracts was obtained by NMR and IR spectroscopy. An integrated technology for wasteless processing of coniferous wood bark was suggested based on the combination of non-isobaric steam activation of bark, extractive isolation of some groups of organic substances, and oxidative pyrolysis of solid residue in a fluidized bed of catalyst.

Catalytic pyrolysis of Kansk-Achinsk lignite for production of porous carbon materials

The process of oxidative pyrolysis of Kansk-Achinsk lignite was studied in a pilot installation with capacity 60 kg h−1. Powdered lignite with a particle size <0.5 mm was pyrolysed in an air-fluidized bed of open-hearth furnace slag particles. In the initial stage of lignite thermal treatment (0.3 s), intensive formation of mesopores is observed. An extended micropore system is formed in the following stage of char interaction with gaseous products of lignite pyrolysis. The process parameters for producing char with high yield and good sorption ability were found.

Steam cracking of coal-derived liquids and some aromatic compounds in the presence of haematite

Abstract Steam cracking in the presence of haematite catalyst was used for the upgrading of coal hydrogenation liquids with b.p.

Lignin conversion in supercritical ethanol in the presence of solid acid catalysts

The effects of sulfated ZrO2 and ZrO2-Al2O3 catalysts and acidic zeolite catalysts with various Si/Al ratios on the thermal conversion of alkali lignin in supercritical ethanol at 300–400°C and on the composition of the resulting products have been investigated. All of the catalysts enhance lignin conversion into liquid products. The strongest effect with the catalysts based on sulfated ZrO2 is attained at 400°C; with the zeolites, at 350°C. The catalysts diminish the concentration of phenol and its derivatives and increase the concentration of ethers (mainly the 1,1-diethoxyethane concentration) in the liquid products. The zeolite catalysts are preferable, since the reaction over the ZrO2-containing catalysts produces gaseous compounds in higher yields. The maximum lignin conversion and a high yield of low-boiling liquid products are achieved at 350°C with the zeolite catalyst with Si/Al = 30, which contains a high concentration of acid sites that are stable at elevated temperatures. The most abundant phenolic liquid products of lignin conversion over the zeolite catalysts at 350°C are methoxyphenols and their methylated and ethylated derivatives.

Influence of the origin of chars, produced from lignite by different methods, on features of their activation process

Abstract Features of activation of chars, produced from Kansk-Achinsk lignite by different pyrolysis technologies, were studied in installation with a fluidized bed reactor. The influence of lignite carbonization parameters of the char reaction ability towards its activation by water steam and oxygen and char sorption properties was established and discussed. Some relations between the degree of lignite carbonization, the time of treatment and chars surface area, and their sorption ability were found. The empirical equation was obtained describing the dynamics at char gasification at 400–700°C and oxygen concentration 1%–4%.