Catalytic sulfation of betulin with sulfamic acid : experiment and DFT calculation

Betulin is an important triterpenoid substance isolated from birch bark, which, together with its sulfates, exhibits important bioactive properties. We report on a newly developed method of betulin sulfation with sulfamic acid in pyridine in the presence of an Amberlyst(®)15 solid acid catalyst. It has been shown that this catalyst remains stable when being repeatedly (up to four cycles) used and ensures obtaining of sulfated betulin with a sulfur content of ~10%. The introduction of the sulfate group into the betulin molecule has been proven by Fourier-transform infrared, ultraviolet-visible, and nuclear magnetic resonance spectroscopy. The Fourier-transform infrared (FTIR) spectra contain absorption bands at 1249 and 835–841 cm(−1); in the UV spectra, the peak intensity decreases; and, in the nuclear magnetic resonance (NMR) spectra, of betulin disulfate, carbons С3 and С28 are completely shifted to the weak-field region (to 88.21 and 67.32 ppm, respectively) with respect to betulin. Using the potentiometric titration method, the product of acidity constants K(1) and K(2) of a solution of the betulin disulfate H(+) form has been found to be 3.86 × 10(–6) ± 0.004. It has been demonstrated by the thermal analysis that betulin and the betulin disulfate sodium salt are stable at temperatures of up to 240 and 220 °C, respectively. The density functional theory method has been used to obtain data on the most stable conformations, molecular electrostatic potential, frontier molecular orbitals, and mulliken atomic charges of betulin and betulin disulfate and to calculate the spectral characteristics of initial and sulfated betulin, which agree well with the experimental data

Study of Composition and Thermal Properties of Ethanollignin Isolated from Aspen-Wood

Методами ИК-спектроскопии, элементного анализа и термогравиметрии охарактеризован этаноллигнин, выделенный из древесины осины. В ИК-спектре этаноллигнина присутствуют полосы поглощения, характерные для фенольных структурных фрагментов гваяцильного и сирингильного типа, алифатических структурных единиц, а также карбоксильных групп. Методом термогравиметрии установлено, что термическое разложение этаноллигнина осины протекает в две стадии, которые проявляются на дифференциальной кривой потери массы в виде перегиба при 300 °C и ярко выраженного пика с максимумом при 390 °C. Изучено влияние температуры на конверсию этаноллигнина в сверхкритическом этаноле, а также на выход и состав жидких и газообразных продуктов. Наиболее высокая конверсия лигнина (74 мас. %) достигнута при температуре 280 °C, а максимальный выход бензолрастворимой фракции жидких продуктов (42 мас. %) – при 300 °C. Методом хромато-масс-спектрометрии установлено, что увеличение температуры процесса деполимеризации этаноллигнина в сверхкритическом этаноле с 280 до 300 °C приводит к росту в образующихся жидких продуктах относительного содержания метоксифенолов (в 1,6 раза) и метоксибензолов (в 2,3 раза)Ethanollignin isolated from aspen wood was characterized by FTIR spectroscopy, elemental and thermogravimetric analysis. IR spectrum of ethanollignin contains adsorption bands characteristic for phenolic structural units of guaiacyl and syringyl types as well as aliphatic fragments and carboxylic groups. According to thermogravimetric data, the thermal decomposition of ethanollignin proceeds in two stages. This is indicated by the appearance on the differential curve on the mass loss the peak of low intensity at 300 °C and the intensive peak at 390 °C. The influence of temperature on the conversion of ethanollignin in supercritical ethanol and on the yield and composition of liquid and gaseous products was investigated. The highest conversion of lignin (74 wt. %) was achieved at temperature 280 °C as well as the maximum yield of benzene-soluble fraction of liquid products (42 wt. %) – at 300 °C. It was defined by GC-MS that the rise of the temperature of ethanollignin depolymerization in supercritical ethanol from 280 °C to 300 °C increases in the obtained liquid products the relative content of methoxyphenols (by 1,6 times) and methoxybenzene (by 2,3

Fractionation of Birch Wood by Integrating Alkaline-Acid Treatments and Hydrogenation in Ethanol over a Bifunctional Ruthenium Catalyst

For the first time, the fractionation of birch wood into microcrystalline cellulose, xylose and methoxyphenols is suggested based on the integration of alkali-acid pretreatments and hydrogenation in ethanol over a bifunctional Ru/C catalyst. It is established that removal of hemicelluloses during pretreatments of birch wood influences the yields of the liquid, gaseous and solid products of the non-catalytic and catalytic hydrogenation of pretreated samples in ethanol at 225 °C. The bifunctional Ru/carbon catalyst affects in different ways the conversion and yields of products of hydrogenation of the initial and acid- and alkali-pretreated birch wood. The most noticeable influence is characteristic of the hydrogenation of the acid-pretreated wood, where in contrast to the non-catalytic hydrogenation, the wood conversion and the yields of liquid products increase but the yields of the solid and gaseous products decrease. GC-MS, gel permeation chromatography and elemental analysis were used for characterization of the liquid product composition. The molecular mass distribution of the liquid products of hydrogenation of the initial and pretreated wood shifts towards the low-molecular range in the presence of the catalyst. From the GC-MS data, the contents of monomer compounds, predominantly 4-propylsyringol and 4-propanolsyringol, increase in the presence of the ruthenium catalyst. The solid products of catalytic hydrogenation of the pretreated wood contain up to 95 wt% of cellulose with the structure, similar to that of microcrystalline cellulose

Reductive Catalytic Fractionation of Spruce Wood over Ru/C Bifunctional Catalyst in the Medium of Ethanol and Molecular Hydrogen

Reductive catalytic fractionation (RCF) has emerged as an effective lignin-first biorefinery strategy to depolymerize lignin into tractable fragments in high yields. Herein, we propose the RCF of spruce wood over a Ru/C bifunctional catalyst in the medium of ethanol and molecular hydrogen to produce monomeric phenolic compounds from lignin, polyols from hemicelluloses, and microcrystalline cellulose. This contribution attempts to elucidate the role of the Ru/C bifunctional catalysts characteristics. The results clarify the particular effect of the carbon support acidity, catalyst grain size, content and dispersion of Ru on the effectiveness of lignin and hemicelluloses extraction and the yields of liquid and gaseous products. The most efficient catalysts for RCF of spruce wood, providing high yields of the monomeric phenols, glycols, and solid product with content of cellulose up to 90 wt%, bear 3 wt% of Ru with a dispersion of 0.94 based on an acidic oxidized graphite-like carbon support Sibunit®, and having a grain size of 56–94 μm. The Ru/C catalysts intensify the reactions of hydrodeoxygenation of liquid products from lignin. The main phenolic monomers are 4-propyl guaiacol, 4-propenyl guaiacol, and 4-propanol guaiacol. We explored the effect of the process temperature and time on the yield and composition of the liquid, solid, and gaseous products of spruce wood RCF. The optimal trade-off between the yields of phenolic monomers (30.0 wt%). polyols (18.6 wt%) and the solid product containing 84.4 wt% of cellulose is reached at 225 °C and 3 h over the most acidic Ru/C catalyst

Reductive Catalytic Fractionation of Spruce Wood over Ru/C Bifunctional Catalyst in the Medium of Ethanol and Molecular Hydrogen

Reductive catalytic fractionation (RCF) has emerged as an effective lignin-first biorefinery strategy to depolymerize lignin into tractable fragments in high yields. Herein, we propose the RCF of spruce wood over a Ru/C bifunctional catalyst in the medium of ethanol and molecular hydrogen to produce monomeric phenolic compounds from lignin, polyols from hemicelluloses, and microcrystalline cellulose. This contribution attempts to elucidate the role of the Ru/C bifunctional catalysts characteristics. The results clarify the particular effect of the carbon support acidity, catalyst grain size, content and dispersion of Ru on the effectiveness of lignin and hemicelluloses extraction and the yields of liquid and gaseous products. The most efficient catalysts for RCF of spruce wood, providing high yields of the monomeric phenols, glycols, and solid product with content of cellulose up to 90 wt%, bear 3 wt% of Ru with a dispersion of 0.94 based on an acidic oxidized graphite-like carbon support Sibunit®, and having a grain size of 56–94 μm. The Ru/C catalysts intensify the reactions of hydrodeoxygenation of liquid products from lignin. The main phenolic monomers are 4-propyl guaiacol, 4-propenyl guaiacol, and 4-propanol guaiacol. We explored the effect of the process temperature and time on the yield and composition of the liquid, solid, and gaseous products of spruce wood RCF. The optimal trade-off between the yields of phenolic monomers (30.0 wt%). polyols (18.6 wt%) and the solid product containing 84.4 wt% of cellulose is reached at 225 °C and 3 h over the most acidic Ru/C catalyst

Thermal Conversion of Flax Shives in Sub- and Supercritical Ethanol in the Presence of Ru/C Catalyst

Thermal conversion of flax shives was studied in sub- and supercritical ethanol medium at 225 and 250 °C in the presence of the bifunctional catalyst 3% Ru/C. The use of 3% Ru/C catalyst in the process of thermal conversion of flax shives in supercritical ethanol was found to increase the conversion of the shives by 27% and the yield of liquid products by 10%. The use of 3% Ru/C catalyst in sub- and supercritical ethanol led to the destruction of both lignin and cellulose. The degree of delignification in the non-catalytic thermal conversion increased upon transition from subcritical (225 °C) to supercritical (250 °C) conditions. Main monomeric products of the thermal conversion process were guaiacylpropene or guaiacylpropane depending on the process temperature. In the presence of Ru/C catalyst, the molecular weight distribution was shifted towards an increase in the content of monomeric compounds in the liquid products

Study of Composition and Thermal Properties of Ethanollignin Isolated from Aspen-Wood

Методами ИК-спектроскопии, элементного анализа и термогравиметрии охарактеризован этаноллигнин, выделенный из древесины осины. В ИК-спектре этаноллигнина присутствуют полосы поглощения, характерные для фенольных структурных фрагментов гваяцильного и сирингильного типа, алифатических структурных единиц, а также карбоксильных групп. Методом термогравиметрии установлено, что термическое разложение этаноллигнина осины протекает в две стадии, которые проявляются на дифференциальной кривой потери массы в виде перегиба при 300 °C и ярко выраженного пика с максимумом при 390 °C. Изучено влияние температуры на конверсию этаноллигнина в сверхкритическом этаноле, а также на выход и состав жидких и газообразных продуктов. Наиболее высокая конверсия лигнина (74 мас. %) достигнута при температуре 280 °C, а максимальный выход бензолрастворимой фракции жидких продуктов (42 мас. %) – при 300 °C. Методом хромато-масс-спектрометрии установлено, что увеличение температуры процесса деполимеризации этаноллигнина в сверхкритическом этаноле с 280 до 300 °C приводит к росту в образующихся жидких продуктах относительного содержания метоксифенолов (в 1,6 раза) и метоксибензолов (в 2,3 раза)Ethanollignin isolated from aspen wood was characterized by FTIR spectroscopy, elemental and thermogravimetric analysis. IR spectrum of ethanollignin contains adsorption bands characteristic for phenolic structural units of guaiacyl and syringyl types as well as aliphatic fragments and carboxylic groups. According to thermogravimetric data, the thermal decomposition of ethanollignin proceeds in two stages. This is indicated by the appearance on the differential curve on the mass loss the peak of low intensity at 300 °C and the intensive peak at 390 °C. The influence of temperature on the conversion of ethanollignin in supercritical ethanol and on the yield and composition of liquid and gaseous products was investigated. The highest conversion of lignin (74 wt. %) was achieved at temperature 280 °C as well as the maximum yield of benzene-soluble fraction of liquid products (42 wt. %) – at 300 °C. It was defined by GC-MS that the rise of the temperature of ethanollignin depolymerization in supercritical ethanol from 280 °C to 300 °C increases in the obtained liquid products the relative content of methoxyphenols (by 1,6 times) and methoxybenzene (by 2,3

Hydrogenation of Flax Shives in Ethanol over a Ni/C Catalyst

Hydrogenation of flax shives in ethanol over bifunctional Ni/C catalysts at 225 °C has been studied. It has been shown that the 10% Ni/C catalyst enhances the yield of monomeric products from 1.1 to 9.7 wt %, decreases the solid product content from 45 to 35 wt %, and increases the degree of delignification to 91%. The main monomeric compounds obtained during hydrogenation are propyl guaiacol and propenyl guaiacol. It has been established that an increase in the mass transfer intensity via increasing the stirring rate or decreasing the catalyst grain size leads to an increase in the total yield of monomeric compounds and the propanol guaiacol yield. Alkaline and acid pretreatment increases the cellulose content in the solid product from 42 to 73 wt %. The proposed sequential scheme of the transformation and formation of monomeric products over the bifunctional nickel catalyst is lignin—coniferyl alcohol—4-propanol guaiacol—4-propenyl guaiacol—4-propyl guaiacol

Conversion of Ethanol-Lignin from Pine Wood in a Supercritical Ethanol in the Presence of Borate-Containing Alumina Catalysts

Изучено влияние температуры на конверсию этаноллигнина древесины сосны в сверхкритическом этаноле, на выход и состав образующихся продуктов. В отсутствии катализаторов максимальный выход жидких продуктов термопревращения этаноллигнина (60 мас. %) получен при температуре 300 °C. По данным хромато-масс-спектрометрии, растворимые в этаноле продукты представлены в основном фенолами, метоксифенолами и этиловыми эфирами карбоновых кислот. Повышение температуры конверсии этаноллигнина до 400 °C интенсифицирует превращение жидких продуктов в твердые и газообразные вещества и приводит к уменьшению содержания в жидких продуктах метоксифенолов в 3 раза и сложных эфиров карбоновых кислот в 2 раза. Использование катализаторов на основе боратсодержащего оксида алюминия в процессе конверсии этаноллигнина в сверхкритическом этаноле при 300 °C способствует увеличению выхода жидких продуктов, выкипающих до 180 °C, в 3,4-3,6 раза и выхода метоксифенолов в 1,4-1,7 раза по сравнению с некаталитическим процессомThe influence of temperature on the conversion of ethanol-lignin in supercritical ethanol and on the yield and composition of the products formed was studied. In the absence of catalysts, the highest yield (60 wt.%) of liquid products of thermal conversion of ethanol-lignin was obtained at the temperature of 300 °C. According to GC-MS data, the ethanol-soluble products mainly consist of phenols, methoxyphenols and ethyl esters of carboxylic acids. The increase of the temperature of ethanol-lignin conversion to 400 °C intensifies the transformation of liquid ethanol-soluble products into solid and gaseous substances and leads to a decrease in ethanol-soluble products the content of methoxyphenols by 3 times and of carboxylic acid esters by 2 times. The use of catalysts, based on borate-containing alumina in the process of ethanol-lignin conversion in a supercritical ethanol at the temperature 300 °C increases the yield of products, boiling up to 180 °C by 3,4-3,6 times and rises the yield of methoxyphenols by 1,4-1,7 times in comparison with a non-catalytic proces

Reductive Catalytic Fractionation of Abies Wood into Bioliquids and Cellulose with Hydrogen in an Ethanol Medium over NiCuMo/SiO₂ Catalyst

Noble metal-based catalysts are widely used to intensify the processes of reductive fractionation of lignocellulose biomass. In the present investigation, we proposed for the first time using the inexpensive NiCuMo/SiO2 catalyst to replace Ru-, Pt-, and Pd-containing catalysts in the process of reductive fractionation of abies wood into bioliquids and cellulose products. The optimal conditions of abies wood hydrogenation were selected to provide the effective depolymerization of wood lignin (250 °C, 3 h, initial H2 pressure 4 MPa). The composition and structure of the liquid and solid products of wood hydrogenation were established. The NiCuMo/SiO2 catalyst increases the yield of bioliquids (from 36 to 42 wt%) and the content of alkyl derivatives of methoxyphenols, predominantly 4-propylguaiacol and 4-propanolguaiacol. A decrease in the molecular mass and polydispersity (from 1870 and 3.01 to 1370 Da and 2.66, respectively) of the liquid products and a threefold increase (from 9.7 to 36.8 wt%) in the contents of monomer and dimer phenol compounds were observed in the presence of the catalyst. The solid product of catalytic hydrogenation of abies wood contains up to 73.2 wt% of cellulose. The composition and structure of the solid product were established using IRS, XRD, elemental and chemical analysis. The data obtained show that the catalyst NiCuMo/SiO2 can successfully replace noble metal catalysts in the process of abies wood reductive fractionation into bioliquids and cellulose