HETEROGENEOUS CATALYTIC FRACTIONATION OF BIRCH-WOOD BIOMASS INTO MICROCRYSTALLINE CELLULOSE, XYLOSE AND ENTEROSORBENTS

For the first time, it was proposed to fractionate the main components of birch wood into microcrystalline cellulose, xylose and enterosorbents by integrating heterogeneous catalytic processes of acid hydrolysis and peroxide delignification of wood biomass. The hydrolysis of wood hemicelluloses into xylose is carried out at a temperature of 150 °C in the presence of a solid acid catalyst Amberlyst® 15. Then the lignocellulosic product undergoes peroxide delignification in a "formic acid – water" medium in the presence of a solid TiO2 catalyst to obtain microcrystalline cellulose (MCC) and soluble lignin. Under the determined optimal conditions (100 °С, Н2О2 – 7.2 wt.%, НСООН – 37.8 wt.%, LWR 15, time 4 h), the yield of MCC reaches 64.5 wt.% and of organosolvent lignin 11.5 wt% from the weight of prehydrolyzed wood. By the treatment of organosolvent lignin with a solution of 0.4% NaHCO3 or hot water the enterosorbents were obtained, whose sorption capacity for methylene blue (97.7 mg/g) and gelatin (236.7 mg/g) is significantly higher than that of the commercial enterosorbent Polyphepan (44 mg/g and 115 mg/g, respectively). The products of catalytic fractionation of birch wood are characterized by physicochemical (FTIR, XRD, SEM, GC) and chemical methods.

Numerical Optimization of the Process of Cellulose Isolation by Peroxide Delignification of Birch Wood in Acetic Acid-Water Medium in the Presence of TiO₂ Catalyst

The possibility of isolation of high-quality cellulose by peroxide delignification of birch wood in an acetic acid-water medium in the presence of a TiO2 catalyst at a temperature of 100 °C was shown. The influence of the process conditions (concentration of hydrogen peroxide and acetic acid, liquid/wood ratio (LWR)) on the yield and composition of cellulose products was established. Numerical optimization of the process was carried out using a full factorial experiment. The optimal conditions for isolation from birch wood a cellulose product with residual lignin content of ≤ 1 wt.% are: СН3СООН concentration 23.8 wt.%, Н2О2 concentration 4.9 wt.%, LWR14.9, temperature 100 °C, time 4 h. Under these optimal conditions, the yield of a cellulose product with a cellulose content of 92.5 wt.% was 49.9 wt.%

PEROXIDE DELIGNIFICATION OF THE VEGETATIVE PART OF JERUSALEM ARTICHOKE IN THE MEDIUM ACETIC ACID-WATER

The purpose of this work was to evaluate the vegetative part of Jerusalem artichoke as a raw material for the production of cellulose using redox-organosolvent delignification in the medium "CH3СOOН – H2O2 – H2O". The chemical composition of the vegetative part of Jerusalem artichoke and the influence of technological parameters of the delignification process on the yield and properties of the cellulose product were studied. It was found that the vegetative part of Jerusalem artichoke collected in October (stems without leaves) with a chemical composition of more than 50 wt.% of polysaccharides in which presented the Kurshner-Hoffer cellulose more than 90 wt.% was more promising for processing. Experimental methods have been used to determine the parameters of the process of delignification of the vegetative part of Jerusalem artichoke, which provide a high yield of cellulose (42.1 wt.%) with a low content of residual lignin (1.1 wt.%): content of H2O2 – 6.5 wt.%, CH3COOH – 23.4 wt.%, GM 15, duration – 2.5 h, catalyst H2SO4 – 0.2 wt.%. It is shown that pre-extraction of the vegetative part of Jerusalem artichoke with a 0.3% solution of dicarboxylic acids at a temperature of 80 °C with a liquid modulus of 10 for 3 hours reduces the content of residual lignin in the cellulose product to 0.5 wt.% and obtain an extract whose yield is – 7.8 wt.%, including a PB of 4.2 wt.%, which makes it promising for biochemical processing. The obtained results expand the areas of use of the vegetative part of Jerusalem artichoke and show the prospects for further more depth research to optimize the process of delignification and study the properties of the cellulose product.

Experimental and mathematical optimization of the peroxide delignification of larch in the presence of MnSO4 catalyst

Experimental and mathematical methods were used to obtain the optimal parameters of peroxide delignification of larch in the presence of MnSO4 catalyst, which provide a high yield of cellulose (44.3 wt.%) with a low content of residual lignin: temperature 100 °C, content of H2O2 6 wt.%, CH3COOH 25 wt.%, hydromodulus 15, and duration 3 h. The cellulose produced under optimal conditions had the following chemical composition: cellulose 92.7 wt.%, lignin 0.6 wt.%, and hemicellulose 5.7 wt.%. IR spectroscopy and XRD studies revealed that the structure of cellulose produced from larch is similar to that of industrial microcrystalline cellulose. The proposed catalytic method allows obtaining larch-derived cellulose with a minimum content of lignin under mild conditions in a single step with a high yield, crystallinity 0.8 and crystallite size 3.0 nm.

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

The work describes a one-stage method of cellulose obtaining from fir wood based on peroxide delignification of wood under mild conditions (100 °C, atmospheric pressure) in the presence of acetic acid, water and catalyst of 2% wt. H2SO4. The possibility of obtaining cellulose with a residual lignin content <1% wt. at a low concentration of hydrogen peroxide (3% wt.) in the reaction medium was established. The optimal concentrations of reagents (Н2О2 – 3% wt., CH3COOH – 38.9% wt.) and the duration of the process (4 h) were determined by experimental and calculation methods. This conditions provide a high yield of cellulose product (≥45% wt.) with a low content of residual lignin (<1% wt.). The composition and structure of fir cellulose was studied by chemical analysis and by FTIR and SEM methods. The cellulosic product which was obtained in optimal process conditions is high-quality cellulose

Optimization of the Process of Abies Wood Peroxide Delignification in the Medium “Formic Acid-Water” in the Presence of TiO₂ Catalyst

The experimental and mathematical optimization of abies wood peroxide delignification process in the formic acid – water medium in the presence of TiO₂ catalyst was carried out. It was established that in the temperature range 70-100 °С the rate constants of the delignification process vary between 0.4 and 3.2 · 10-4 min-1. The optimal parameters for the production of cellulose product with a residual lignin content of ≤ 3 wt.% were determined (temperature 100 °С, concentration Н₂О₂ 10 wt.%, НCOOН 38 wt.%, LWR 15, time 4 h). The features of abies wood peroxide delignification processes in the presence of TiO₂ catalyst in “ formic acid – water” and “acetic acid – water” were compared. It was shown the possibility of abies wood fractionation in the medium “ formic acid-water” to high-quality cellulose with the yield of 94 wt.% (the content of residual lignin 2.3 wt.%) and to low molecular weight lignin with the yield of 21 wt.% (average molecular weight 1854 g/mol and polydispersity 1.65). The obtained chemically active lignin can be used for the production such valuable products as enterosorbents, nanoporous carbon materials, aerogels

REGULARITIES OF THE PROCESS OF PINE WOOD PEROXIDE DELIGNIFICATION IN THE PRESENCE OF SULFURIC ACID CATALYST

The known methods to obtain microcrystalline cellulose (MCC) from wood raw material is multi-stage and it is based on the integration of environmentally hazardous processes of pulping, bleaching and acid hydrolysis of cellulose amorphous part. The paper describes a one-stage catalytic method to obtain microcrystalline cellulose from pine wood based on peroxide delignification in acetic acid-water in the presence of a catalyst H2SO4. The optimal parameters of the process of pine wood peroxide delignification in the presence of 2% H2SO4 catalyst were determined by experimental and numerical methods: temperature – 100 °C, concentration H2O2 – 5 wt.%, CH3COOH – 25 wt.%, LWR 15, duration – 4 h. They provide a high yield of cellulose (45.2 wt.%) with a low content of residual lignin (1.0 wt%).The kinetic study of pine wood peroxide delignification at the temperature range 70-100 ºC was accomplished. The delignification process is described satisfactory by the first order equation in all temperature range. The rate constants vary between 0.08·10-4 and 2.15·10-4 s-1 and the activation energy is 90 kJmol-1. It was established by FTIR and XRD methods, that the cellulose, obtained from pine wood has the composition and structure similar to the commercial microcrystalline cellulose.