Processes of catalytic oxidation for the production of chemicals from softwood biomass

Abstract

Two alternative routes of softwood catalytic oxidative fractionation on cellulose products and fine chemicals are assessed.We suggested 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 (NH 4 ) 6 Mo 7 O 24 to produce microcrystalline cellulose (35.0 wt% on wood), microfibrillated cellulose (7.5 wt% on wood), nanocrystalline cellulose (3.7 wt% on wood) and low molecular weight organic compounds (20 wt% on wood). The developed process reduces the number of technological stages and increase an environmentally safety of nanocelluloses production from wood, compared to traditional technologies.Another suggested process of softwood (pine and larch) fractionation on vanillin (up to 4.7 wt% on wood) and cellulose (up to 34.6 wt% on wood) is based on wood oxidation by oxygen in water-alkaline medium at temperatures 160-180 °C in the presence of suspended catalyst Cu(OH) 2 . The further acid conversion of cellulose by 2 % H 2 SO 4 at 180 °C produces levulinic acid with the yield up to 9.7 wt % on wood.The integration of the processes of dihydroquercetin and arabinogalactan extraction isolation from larch wood, oxidation of extracted wood by oxygen to vanillin and cellulose in the presence of catalyst Cu(OH) 2 , acid catalyzed conversion of cellulose to levulinic acid and arabinogalactan hydrolysis over solid acid catalyst to arabinose and galactose leads to an increase in the number of target products. FTIR, XRD, SEM, AFM solid state 13 C CP/MAS and chemical methods were used for characterization of cellulose products. Organic compounds were identified by GC, HPLC and GC-MS methods.The two alternative schemes of larch wood catalytic oxidative biorefinery to produce nanocelluloses and fine chemicals have been developed.

Physicochemical characteristics of polysaccharides from catalytic and noncatalytic acetic acid-peroxide delignification of larch wood

“…The polysaccharides were extracted from the spent liquors of the catalytic and noncatalytic larch wood delignification after the cellulose isolation. The conditions for delignification were chosen on the basis of earlier study [19], where it was shown that, at a temperature of 100 °C, a hydrogen peroxide content of 6 wt%, an acetic acid of 30 wt%, and a LWR of 15, the deepest delignification of wood occurs, which ensures a residual lignin content below 1% in the cellulose product. In this case, water-soluble low-molecularweight lignin degradation products, as well as polysaccharides, pass into the solution.…”

“…As shown in Table 1, the polysaccharide yield at a process temperature of 90 °C is lower than that at 100 °C. This is due to the fact that at 100 °C the process of wood delignification is more complete [19,20] and, therefore, a greater amount of structural polysaccharides passes into liquor 1. The use of the (NH 4 ) 6 Mo 7 O 24 and MnSO 4 catalysts ensures a fairly high yield of polysaccharides already at 90 °C.…”

“…Currently, new methods of cellulose production are being developed, which is based on the peroxide delignification of wood in organic solvents, e.g., acetic and formic acids, and in the presence of various catalysts [19][20][21]. The treatment of wood with organic solvents as delignification media allows the lignocellulosic materials to be fractionated to produce lignin, cellulose, and hemicelluloses, thereby providing an excellent approach in terms of biomass use.…”

“…Studies [20,21] were devoted to the oxidative catalytic delignification of various timber species in the hydrogen peroxide-acetic acid-water medium in the presence of the solid TiO 2 catalyst and the soluble MnSO 4 one. The study [19] compared the catalytic properties of the soluble (CuSO 4 , ZnSO 4 , MnSO 4 , FeSO 4 , and (NH 4 ) 6 Mo 7 O 24 ) and solid (TiO 2 , KN-30, and C-FeZSM-5 zeolites) catalysts for delignification of wood including the same solvent. The main attention in these works was paid to the yield and composition of solid cellulosic products.…”

Study of Regularities and Optimization of the Process of Fir Wood Peroxide Delignification in the Medium of “Acetic Acid – Water” in the Presence of Sulfuric Acid Catalyst

“…Численную оптимизацию процесса каталитической пероксидной делигнификации древесины ели проводили с применением пакета прикладных программ Statgraphics Centurion XVI, блок DOE (Design of Experiment) [17].…”