The first green biorefinery of larch wood based on the fractionation of biomass into dihydroquercetin (DHQ), arabinogalactan (AG), microcrystalline cellulose (MCC) and soluble lignin (SL) is reported. The new green method of one-step isolation of DHQ and AG from larch wood by ethanol–water solution was developed. The first results of kinetic studies and optimization of the process of extracted larch wood peroxide fractionation into MCC and SL in acetic acid–water medium in the presence of green TiO2 catalyst are described. The products obtained from larch wood were characterized by FTIR, NMR, XRD, AFM and chemical methods. The scheme of larch wood biorefinery is suggested which integrates the developed processes of woody biomass fractionation into DHQ, AG, MCC and SL. All developed methods use non-toxic and less-toxic reagents, such as water, ethanol, hydrogen peroxide and acetic acid.

Results of the study on green valorization of hardwood biomass into valuable chemicals with the use of solid catalysts were described. The heterogeneous catalytic processes of hemicelluloses and cellulose hydrolysis, wood oxidative fractionation and lignin depolymerization in supercritical spirits are suggested to employ for the green biorefinery of hardwood to xylose, pure cellulose, glucose, alcohols and liquid hydrocarbons.

It was established that the main factors responsible for the yield and specific surface area of porous carbon materials obtained by the chemical activation of the wood of birch are the nature of a modifying agent and the temperature of pyrolysis. The additional opening of the porous structure of the product of the chemical activation of wood occurs at the stage of its water treatment as a result of the removal of water-soluble compounds. The conditions of the carbonization of birch wood modified with H 3 PO 4 , KOH, and ZnCl 2 were chosen in order to provide the significant development of the porous structure of carbon materials. The porous carbon material with the highest specific surface area (more than 2560 m 2 /g) was obtained by the water washing of the product of the carbonization of birch wood modified H 3 PO 4 at 400°C.

Carbonization of betulin (betulinol) as an individual carbon precursor was studied in the temperature range of 400–800°C in the presence of KOH. Differential thermal analysis and IR spectroscopy were used to determine the influence of KOH on major structural changes and the chemical composition of betulin, which occur at 400–500°C. It was shown by scanning electron microscopy and BET analysis that KOH promoted the formation of a developed specific surface (S BET 1350–2100 m 2 /g) at temperatures of 600–800°C and had the greatest influence on the textural and adsorption properties of the resulting porous carbon adsorbents. It has been found that the formation of microporous carbon materials with a pore size of 1.92 nm and a specific micropore surface area of 1275 m 2 /g is possible upon the activation of betulin with KOH at 800°C. Betulin may be proposed to control the porosity of the carbon carriers derived from birch wood.

Certain fundamental aspects of how the porous structure is formed in carbon materials produced by pyrolysis of microcrystalline cellulose modified with phosphoric acid, potassium hydroxide, and zinc chloride were determined. The above chemical promoters shift the onset of the process of intense thermal transformation of cellulose to lower temperatures and promote formation of porous carbon materials. Water treatment of porous carbon materials produced by pyrolysis of microcrystalline cellulose with high content of a promoter leads to additional pore opening due to the removal of the excess amount of the promoter and soluble products formed in its interaction with cellulose, which makes it possible to obtain porous carbon materials with specific surface area of up to 1500 m2 g−1.

The effect of the conditions of consecutive carbonization–activation of the bark of larch, fir tree, and birch in a fluidized bed reactor on the yield, textural characteristics, and sorption properties of the resulting porous carbon materials was studied. The rate of temperature increase at the stage of the pyrolysis of bark exerted the greatest effect on the specific surface area, total pore volume, and sorption capacity of porous carbon materials for iodine and methylene blue. The porous carbon materials obtained by the slow pyrolysis (5 K/min) of larch bark with an isothermal exposure for 60 min at 600°C and the subsequent activation with CO 2 at 850°C for 30 min were characterized by a maximum sorption activity. The porous carbon materials obtained from bark by consecutive carbonization–activation in a fluidized bed were similar to commercial powder sorbents from wood in their characteristics.

An effect of different methods for aspen wood activation (grinding in the mills of different types, explosive autohydrolysis, catalytic oxidation by hydrogen peroxide and the combination of these methods) exerted on the structure, chemical composition and reactivity of activated wood was studied. It has been found that all the methods of aspen wood mechanical pretreatment result in changing the supramolecular structure, chemical composition and reactivity thereof: activated samples exhibit increasing the content of readily hydrolysable polysaccharides, with reducing the concentration of polysaccharides difficult to hydrolyze and of residual lignin, as well as with increasing the rate of polysaccharide acidic hydrolysis into monosaccharides and the rate of lignin oxidation by hydrogen peroxide.

Composition and binding properties of acetic acid lignins obtained at oxidative catalytic delignification of different types of plant biomass (softwood, hardwood, wheat straw) in the medium: acetic acid hydrogen peroxide - water - sulfuric acid catalyst were compared.Obtained acetic acid lignins have high concentration of reactive oxygen-containing functional groups, therefore they can be used as low-toxic binding agent for production of wood panel materials with good strength characteristics. The influence of lignin nature, its content in lignin/wood blend and conditions of pressing on the bending strength and water-resistance of obtained wood panel materials was studied. Optimal technological parameters for manufacture of strong and water steady wood panels were found.

The composition of the soluble products of wheat straw delignification in the medium acetic acid- hydrogen peroxide-water-sulphuric acid catalyst was studied by means of elemental and chemical analysis, IR spectroscopy and gas chromatography-mass spectrometry. It was established that the vat residue formed in the regeneration of spent alkali liquor contains the products of polysaccharide degradation (4.7 rel. %), esters (19.9 rel. %) and sterols (37.2 rel. %). The acetic lignin precipitated from the alkali liquor contains a substantial amount of oxygen-containing functional groups. A promising character was demonstrated experimentally for the presently unclaimed bio-renewable resource such as wheat straw as a chemical raw material for obtaining sorbents and binders in the production of wood-based panels.

The different methods of wood biomass thermal liquefaction at atmospheric and elevated pressures were investigated in order to select the more effective one. Wood biomass liquefaction by melted formate/alkali mixtures and with the use of metallic iron/Na2CO3 system is carried out at low pressures. But these methods give only moderate yield of bio-liquids. The highest yield of bio-liquid was obtained in the process of biomass dissolvation in methanol media in the presence of Zn–Cr–Fe catalyst at 20 MPa. Co-pyrolysis and co-hydropyrolysis of biomass/polyolefine mixtures makes it possible to obtain the rather high yield of bio-liquid at the moderate pressures (3 MPa).

The present paper describes the results of studies directed to novel catalytic processes design for the environmentally friendly production of cellulose. The new delignification catalyst which is produced by chemical interaction of elemental sulfur with hydrazine in superbase medium was used for the improvement of efficiency and ecological purity of the conventional pulping process. This catalyst reduces the concentration of polysulfides in pulping liquor and the yield of side sulfur-containing compounds (by 1.5 times). The processes of wood delignification with sulfur-free reagents based on catalytic pulping with acetic acid and hydrogen peroxide and on the delignification of steam-activated wood with NaOH or Na2CO3 solutions have prospects for the environmentally benign production of cellulose. The new catalytic process of vanillin production by oxidation of lignosulfonates with molecular oxygen was described.