New Methods of Lignin Processing into Organic Low Molecular Compounds and Nanoporous Materials
Development of high-tech methods for utilization of lignins produced in a huge amounts in the industry of lignicellulosic biomass processing is the urgent task. The present paper describes the new promising methods of wood lignins valorization to valuable chemical products, developed in the Institute of Chemistry and Chemical Technology SB RAS, FRC KSC SB RAS. Aromatic aldehydes and organic acids were obtained by catalytic oxidation of lignins by oxygen and hydrogen peroxide, liquid hydrocarbons - by catalytic conversion of lignins in supercritical alcohols. In the medium of supercritical ethanol the high yield of liquid products from lignin has been achieved in the presence of solid catalysts based on sulfated ZrO<sub>2</sub> and on high-silica zeolites in H-form. In the medium of supercritical butanol the high activity in the conversion of lignin to liquid products has been shown by supported on SiO<sub>2</sub> nickel-containing catalysts. New methods of synthesis of nanoporous carbons from lignin including carbon molecular sieves and aerogels with unique properties were developed. It was shown, that thermal alkaline activation of lignin promotes the formation of cabon materials with specific surface area up to 2700 m<sup>2</sup>/g and total pore volume up to 1.4 cm<sup>3</sup>/g. Obtained nanoporous carbon materials show a high sorption activity and have the prospects of their use for separation of gaseous mixtures and for purification of gases and water. The methods of synthesis of nanoporous organic and carbon aerogels on the basis of inexpective lignin- containing mixtures: lignin-tanin-formaldehyde and lignin-phenol-formaldehyde were suggested. Obtained aerogels have a broad potential applications as thermo-insulating materials, sorbents, catalysts, electrodes, electrochemical capacitors.