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The process of synthesis of formic acid via partial peroxide oxidation of methane over Fe-MFI zeolites, as well as the influence of the catalyst activation by oxalic acid on the process parameters (conversion and selectivity) was studied. XRD, ICP-OES, SEM, UV–Vis DR, ESR, NH3-TPD, 27Al MAS NMR, N2 adsorption techniques were used for the catalyst characterization. The observed increase in TOF, selectivity to formic acid and efficiency of H2O2 utilization upon the catalyst activation with oxalic acid was accounted for by the formation of oligomeric oxo-clusters of Fe-ions and by an increase in the total acidity of the catalysts. The process of oxidation of main intermediates of the reaction, such as methanol and formic acid, was studied in the presence and in the absence of methane that allowed the mechanism of methane oxidation to formic acid to be suggested.

Solid acid catalysts of cellulose hydrolysis in aqueous media attract considerable research interest because of the ease of their separation from the reaction products. The nature of interaction between the two solids is a relevant topic of ongoing research. One aspect of behavior of solid acids in water was not previously discussed in literature with regard to hydrolysis of cellulose: electrolytic dissociation and formation of electric double layers. In this work, on theoretical level, we consider the role of the double layer created by the solid acid when cellulose hydrolysis takes place. The diffuse layer of protons is regarded as the medium where the hydrolysis reaction occurs. Protonation of cellulose by these protons imparts positive charge onto its surface, and cellulose is electrostatically attracted to the polyanion of the catalyst. Thus, the two solid surfaces stay close to each other despite Brownian motion; this allows explaining the high activity of solid catalysts even when chemisorption of carbohydrates on a catalyst is not favorable.

Colloidal catalysts for oxidation of water to dioxygen, which are stable on storage and under the reaction conditions, are synthesized based on CoIII , MnIII , FeIII and CuII hydroxides. Stabilization of the colloids with dextrated starch allows the process of hydroxide ageing to be stopped at the stage of the formation of primary nuclei (ca. 2-3 nm from transmission electron microscopy data). Molecular mechanics and dynamic light scattering studies indicate a core-shell type structure of the catalysts, where the hydroxide core is stabilized by the molecular starch network (ca. 5-7 nm). The colloidal catalysts are highly efficient in oxidizing water with one electron oxidant Ru(bpy)3 3+ at pH 7 to 10. The influence of pH, catalyst concentration, and buffer nature on the oxygen yield is studied. The maximal yields are 72, 53, and 78 % over Fe-, Mn- and Co-containing catalysts, respectively, and turnover numbers are 7.8; 54 and 360, respectively. The Cu-containing catalyst is poorly effective to the water oxidation (the maximal yield is 28 % O2 ). The synthesized catalysts are of interest for stopped-flow kinetic studies of the mechanism of the water oxidation and as precursors for anchoring nanosized hydroxides onto various supports in order to develop biomimetic systems for artificial photosynthesis.

We study the contents of elements and group composition in natural organic matter (NOM) that interacts with acid mine drainage (АMD) and high-sulfide tailings at the Ursk site (southwestern Siberia, Russia). AMD causes biomass changes in NOM, related changes in the composition of fractions, and hydrolysis of hydrolyzable compounds; it increases the water-soluble fraction and maintains depolymerization of humic acids to fulvic acids, but exerts no effect on substances soluble in organics (bitumen) or on poorly hydrolyzable compounds. Accumulation of inorganic elements and precipitation of minerals obscure the true fraction composition of NOM: the superposed mineral component contributes significantly to the water-soluble, humic acid, hydrolyzable and non-hydrolyzable fractions, and may reach 26.4% per total of all fractions. Rock-forming and potentially toxic elements partition among NOM fractions and predominate in the water-soluble fraction. The contents of Au and Ag are the highest in the fractions of humic acids and hydrolyzable compounds but are lower in the non-hydrolyzable residue. The obtained data have implications for possible migration of potentially toxic elements and noble metals and thus for remediation of polluted areas. The observed fractionation of Ag and Au in NOM helps us to understand the mechanisms of their distribution in organic-bearing environments, such as peatlands or coal basins.

fff; International audience; Catalytic hydrogenolysis in the medium of supercritical organic solvents is a promising way of wood lignins depolymerization into liquid products.In this study, for the first time, the catalytic properties of bifunctional catalysts Ru/C, Pt/ZrO2, NiCuMo/SiO2, containing nanosized metal particles on acidic groups are compared in the processes of aspen wood and ethanol lignin hydrogenolysis in supercritical ethanol.The most active catalysts are Ru/C and Pt/ZrO2 which provide the high conversion of wood (to 78.0 wt%), significant yield of liquid products (to 50.6 wt%) and low yield of solid rest (to 22.0 wt%) at temperature 250 °C and H2 pressure 9.0 MPa. These catalysts increase the yield of monomeric compounds in liquid products from 10.5 % to 50.4 % on mass of lignin.GC–MS analysis shows that alkyl derivatives of methoxyphenols (mainly propyl syringol and propyl guaiacol) are dominated in liquid products. Solid products of aspen wood catalytic hydrogenolysis contain mainly cellulose (to 82.2 wt%). Therefore, the catalytic hydrogenolysis in supercritical ethanol in the presence of by functional catalysts Ru/C and Pt/ZrO2 allows to fractionate the aspen wood biomass on cellulose and liquid products enriched with propyl syringol and propyl guaiacol.In catalytic hydrogenolysis of ethanol lignin the yield of alkyl derivatives of methoxyphenols is lower compared to wood. This is probably due to the reduced content of reactive β-O-4 bonds in the structure of ethanol lignin compared to native lignin of aspen wood. As follows from the results obtained, native lignin of wood is easier depolymerized to monomeric compounds in the process of catalytic hydrogenolysis than ethanol lignin, isolated from wood.According to GPC data, the catalysts shift to the region of lower molecular mass the molecular mass distribution of liquid products of aspen wood and ethanol lignin hydrogenolysis.

International audience; Glucose is a widely used chemical, food and feedstock. 5-Hydroxymethylfurfural (5-HMF) is one of the platform molecules, which could be applied in chemical and fuel industries. This work presents the possibility of glucose and 5-HMF production from inedible cellulose, which is the main component of renewable plant (wood) biomass via one-pot hydrolysis–dehydration over solid acid catalysts based on Sibunit carbon material. The catalysts prepared via oxidation with wet air mixture, HNO3, sulfonation by fuming H2SO4 at 80–200 °C or combination of the techniques demonstrated high activity under hydrothermal semi-flow conditions. Dependences of both glucose and 5-HMF formation on catalyst acidity and the nature and amount of surface acid groups are revealed. The total surface acidity but not the chemical nature of the groups is responsible for effective cellulose hydrolysis to glucose. On the other hand, sulfo groups demonstrate noticeable activity in 5-HMF formation from glucose. Glucose and 5-HMF can be derived from the polysaccharide with yields up to 75 and 10%, respectively.

Background The Uzon Caldera is one of the places on our planet with unique geological, ecological, and microbiological characteristics. Uzon oil is the youngest on Earth. Uzon oil has unique composition, with low proportion of heavy fractions and relatively high content of saturated hydrocarbons. Microbial communities of the «oil site» have a diverse composition and live at high temperatures (up to 97 °C), significant oscillations of Eh and pH, and high content of sulfur, sulfides, arsenic, antimony, and mercury in water and rocks. Results The study analyzed the composition, structure and unique genetics characteristics of the microbial communities of the oil site, analyzed the metabolic pathways in the communities. Metabolic pathways of hydrocarbon degradation by microorganisms have been found. The study found statistically significant relationships between geochemical parameters, taxonomic composition and the completeness of metabolic pathways. It was demonstrated that geochemical parameters determine the structure and metabolic potential of microbial communities. Conclusions There were statistically significant relationships between geochemical parameters, taxonomic composition, and the completeness of metabolic pathways. It was demonstrated that geochemical parameters define the structure and metabolic potential of microbial communities. Metabolic pathways of hydrocarbon oxidation was found to prevail in the studied communities, which corroborates the hypothesis on abiogenic synthesis of Uzon hydrothermal petroleum.

Solid bifunctional catalysts based on cesium salts of V-containing heteropoly acids (CsHPA: Cs

International audience; The present study was devoted to a kinetic modeling of cellulose hydrolysis-dehydration into platform molecules (glucose and 5-hydroxymethylfurfural) over a carbon solid acid catalyst. Cellulose depolymerization and transformations of the main process intermediates were experimentally studied under hydrothermal conditions in pure water over a catalyst based on sulfonated Sibunit material at 180 °C in a batch reactor. Based on the data obtained, the 18-step kinetic scheme of the process which included the main reaction pathways was proposed as well as the reaction constants were determined. Kinetic parameters showed that solid acid carbon catalysts seems to be more suitable than soluble ones for the production of 5-HMF from sugars. Proposed software modeling of cellulose hydrolysis-dehydration described the experimental results obtained with a sufficient accuracy.

Solid acid catalysts based on graphite-like mesoporous carbon material Sibunit were developed for the one-pot solubilization–hydrolysis–dehydration of cellulose into glucose and 5-hydroxymethylfurfural (5-HMF). The catalysts were produced by treating Sibunit surface with three different procedures to form acidic and sulfo groups on the catalyst surface. The techniques used were: (1) sulfonation by H2SO4 at 80–250 °C, (2) oxidation by wet air or 32 v/v% solution of HNO3, and (3) oxidation-sulfonation what meant additional sulfonating all the oxidized carbons at 200 °C. All the catalysts were characterized by low-temperature N2 adsorption, titration with NaOH, TEM, XPS. Sulfonation of Sibunit was shown to be accompanied by surface oxidation (formation of acidic groups) and the high amount of acidic groups prevented additional sulfonation of the surface. All the Sibunit treatment methods increased the surface acidity in 3–15 times up to 0.14–0.62 mmol g−1 compared to pure carbon (0.042 mmol g−1). The catalysts were tested in the depolymerization of mechanically activated microcrystalline cellulose at 180 °C in pure water. The main products 5-HMF and glucose were produced with the yields in the range of 8–22 wt% and 12–46 wt%, respectively. The maximal yield were achieved over Sibunit sulfonated at 200 °C. An essential difference in the composition of main products obtained with solid acid Sibunit carbon catalysts (glucose, 5-HMF) and soluble in water H2SO4 catalysts (formic and levulinic acids) as well as strong dependence of the reaction kinetics on the morphology of carbon catalysts argue for heterogenious mechanism of cellulose depolymerization over Sibunit.

The structure formation in xerogels of aqueous solutions of products of the UV-initiated formose reaction has been studied in the context of the problem of the spontaneous formation of prebiological structures. Of the 11 variants of xerogels, only in the talopyranose xerogel show the presence of anisometric strings with distinct periodic (in particular, helical) structure, which form characteristic elements of biomimetic structures by interlacing. Under the conditions simulating the primitive Earth’s atmosphere (formaldehyde, water, UV), spontaneous formation of anisometric superhelical structures has been modeled and the type of the sugars forming these structures has been identified.

New composite catalysts were synthesized by pyrolysis of carbon-containing compounds supported of Cu-substituted ZSM-5 zeolite. Three series of the catalysts containing 12 wt% of carbon and 1 wt% of copper were prepared (powder, honeycomb monolith and extruded trefoils) and characterized by TEM, XPS, N2 adsorption. Kinetics of catalytic wet peroxide oxidation (CWPO) of phenol was studied in the presence of the composite catalysts using batch and flow reactors. The substrate conversion in the batch reactor was reached 45% in two minutes over the composite catalyst but no more than 8% in five minutes over the zeolite catalyst. Studies of the granulated composites (monoliths and trefoil) in the flow reactor demonstrated a higher efficiency of the trefoil catalyst. The conversion of phenol at the flow rate 20 mL min−1 was 35% higher over the composite trefoils than over the carbon-free zeolite. The obtained kinetic data allowed the conclusion to be made about different mechanisms of CWPO over zeolite and composite catalysts. The developed kinetic model of phenol CWPO over the composite catalyst described the formation and destruction of intermediate products of phenol oxidation. It was established that inhibiting of phenol oxidation by the substrate was less pronounced in the presence of the composite catalysts than in the presence of the carbon-free catalysts. The flow reactor for phenol oxidation was modeled with account for the external and internal diffusion deceleration of the reaction over real catalyst granules of different geometry to provide adequate description of the experimental results.

The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an sp3-hybridized carbon atom has been detected. It has been shown that this phase is formed due to the spatial cleavage of antipodes in the racemate, similar to the cleavage of enantiomers following the sign of chirality in the known experiments of Pasteur. The results have been obtained under the conditions that correspond to modern ideas about the form and vector of prebiological evolution and, therefore, can be of fundamental importance for understanding the processes of biopoiesis.

It has been found that the UV-initiated formose reaction in an extremely concentrated aqueous solution of formaldehyde gives sugars and other biologically significant chiral compounds with sp3-hybridized carbon atom. The reaction leads to an optically active condensed phase, which is a result of the spontaneous spatial separation of enantiomers in the racemate into the antipodes, similarly to the separation of enantiomers of different chirality sign in the famous Pasteur experiments. In our opinion, such a scenario is as close as possible to the actually realized de novo scenario of synthesis of chiral prebiotic molecules and matrices.

The paper presents data on sapropels from ten lacustrine systems at the Barabinsk and Kulunda plains in Novosibirsk region. The sapropels are classified according to the type of the biological contribution to their origin and the content of organic matter. The sapropel of lakes Kachkulnya and Barchin, which are rich in organic matter and differ by the type of their origin (macrophytogenic and planktonogenic), were studied in much detail with the application of the following techniques: X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and elemental (CHNSO) analysis. Groups of organic compounds contained in the organic matter were determined by successive extraction, and the monosaccharide composition was studied by high-performance liquid chromatography (HPLC). The organic matter of sapropel with different type of boilogical contribution was discovered to differ in elemental (CHNSO) composition, group of organics, and the monosaccharide compositions. Our results led us to conclude that the genesis of sapropel significnalty imprints the composition of its organic matter.

Surveyed in this review are the most important achievements in the research and development of catalysts based on Mn, Fe, Co, and Cu hydroxides for the oxidation of water to molecular oxygen by chemical oxidizing agents obtained, for the most part, at Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences. An analysis of the results of kinetic studies on water oxidation in the presence of the above-menthioned catalysts together with data obtained by quantum chemistry methods allowed us to make a conclusion on the general nature and process mechanism both in the presence of artificial catalytic systems based on metal hydroxides and the natural enzyme photosystem II of green plants. The most important properties of hydroxo compounds responsible for catalytic activity in the oxidation of water by one-electron oxidants are discussed, and a possible reaction mechanism is considered.

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.

Solid acid NbOx/ZrO2 catalysts containing 0, 0.5, 1.1 and 2.8 wt.% of Nb were prepared for one–pot hydrolysis-dehydration of mechanically activated cellulose in pure hot water to produce glucose and 5-hydroxymethylfurfural. The catalysts were characterized (XRD, N2 adsorption, ICP-OES, UV–Vis DRS) and tested in cellulose processing at 453 K. The catalytic activity increased as follows: 0.5%Nb/ZrO2

The reduction of oxygen-containing compounds, which is employed to produce biofuels from plant feedstock, requires a great amount of reductant that is commonly represented by molecular hydrogen obtained from non-renewable fossils. Formic acid can also serve as the reductant or hydrogen source in the production of such fuels. It is shown that formic acid can be obtained from mechanically activated microcrystalline cellulose with high yields (66%) by the one-pot catalytic process of hydrolytic oxidation in the presence of Mo-V-P heteropoly acids (HPA) possessing bifunctional (acidic and oxidizing) catalytic properties. Mechanical activation has a crucial influence on the cellulose reactivity and formic acid yields. The highest yield of formic acid was obtained by using the cellulose activated in a planetary mill, when its crystal structure was mainly crushed. The temperature of 150–160 °C and the oxidizing atmosphere (20% O 2 and 80% N 2 ) are found to be the optimal reaction conditions. Pressure was shown to exert no effect on the observable kinetics of the process. A search for the optimal HPA composition demonstrates that a maximum reaction rate is observed in the presence of HPA that provides the most acidic reaction medium. A linear dependence of the reaction rate on the concentration of H + ions and a more complicated dependence on vanadium content were revealed.

This work addresses the supramolecular self-organization in the xerogels of formose reaction products. The UV-induced formose reaction was held in over-saturated formaldehyde solutions at 70∘C without a catalyst. The solutions of the obtained carbohydrates were dried on a glass slide, and the obtained xerogels demonstrated a prominent optical activity, while the initial solutions were optically inactive. The xerogels contained highly elongated crystalline elements of a helical structure as well as the isometric ones. Thus xerogel formation was accompanied by a spontaneous resolution of enantiomers and separation of different-shaped supramolecular structures. The thick helices were twisted of thinner ones, while the latter were twisted of elementary structures having a diameter much smaller than 400 nm. Similar structural hierarchy is typical of biological macromolecules (DNA, proteins, and cellulose). Summarizing the obtained results, we proposed a hypothetical mechanism explaining the amplification of the initial enantiomeric excess, as well as chiral and chemical purification of the substances which were essential for the evolution of Life to start.

Flax shive is the main waste (up to 70 wt %) in the production of flax fiber. It represents the lignified parts of the flax stem mainly in the form of small straws. Complex processing of such wastes is a significant problem due to the heterogeneity of the chemical structure of lignin. This article presents the results of reductive catalytic fractionation (RCF) of flax shive in ethanol and isopropanol at elevated temperatures (225&ndash, 250 &deg, C) in the presence of a bifunctional catalyst (Ru/C) and molecular hydrogen. This provides solvolytic depolymerization of lignin and hemicelluloses presented in flax shive. Catalytic hydrogenation effectively stabilizes the formed lignin intermediates and prevents repolymerization reactions producing the lignin fraction with a high degree of depolymerization. RCF of flax shive produces solid products with a high cellulose content and liquid products consisting mainly of monophenolic compounds. Furthermore, the effect of different characteristics (the ruthenium content, particle size, and support acidity) of the bifunctional catalysts containing ruthenium nanoparticles supported on mesoporous, graphite-like carbon material Sibunit&reg, 4 on the yield and composition of the products of hydrogenation of flax shive in sub- and super-critical ethanol has been studied. Bifunctional catalysts Ru/C used in the RCF of flax shive increase its conversion from 44 to 56 wt % and the yield of monophenols from 1.1 to 10.2 wt % (based on the weight of lignin in the sample). Using the best Ru/C catalyst containing 3% of Ru on oxidized at 400 &deg, C carbon support, the high degree of delignification (up to 79.0%), cellulose yield (up to 67.2 wt %), and monophenols yield (up to 9.5 wt %) have been obtained.

Sapropels of lake systems in Novosibirsk oblast were studied to develop a scientific basis for their rational use. Sapropels from lakes in Novosibirsk oblast have been classified based on the ash content, chemical composition, and genesis. Organic–mineral and mineral–organic calcium and mixed sapropels of macrophyte and macrophyte–plankton genesis have been shown to be predominant by far among sapropel deposits in lakes in Novosibirsk oblast.

Literature published mainly between 1995 and 2015 in the field of investigations aimed at finding promising new catalysts for the industrial processing of polysaccharide components of lignocellulose biomass, for new methods to achieve these processes, and for new ways of transforming polysaccharides into valuable chemicals and fuel is reviewed. In the first section, modern methods for activating lignocellulose biomass in order to separate main components and/or treat polysaccharide feedstock (cellulose, hemicelluloses) for further processing are considered. The second will deal with catalytic acidic transformations of these components into monosaccharides and furans. The third will focus on with the main focus on the production of 5-hydroxymethylfurfurol the application of biotechnological enzymatic methods for producing valuable chemicals such as ethanol, isobutanol, lactic acid.

The catalytic behavior of perovskite-like oxides LaBO3 (B = Cu, Fe, Co, Ni, Mn) prepared by the Pecini method were examined in wet peroxide oxidation of phenol as a model organic substrate. The study showed the activity of only LaCuO3 and LaFeO3 perovskite-like catalysts, Cu-containing catalysts being more active, though Fe-containing being more stable. The leaching test proved the heterogeneous nature of the catalyst action. The long-term experiments revealed the acceptable stability of the LaFeO3 catalyst. XRD studies of the spent samples demonstrated the stability of the perovskite-like structure of the catalysts during the reaction. The assumption about the nature of the active sites and the possible mechanism of the reaction was proposed based on of the XPS study.

The wet peroxide oxidation of phenol over the extruded 1.5%Cu/(80%H-ZSM-5 + 20%Al 2 O 3 ) catalysts of the different geometric forms and sizes (cylinders with diameters 1, 2, 3 mm, trefoils, spheres and monoliths with size of channels 1.0 × 1.0, 1.5 × 1.5 mm) was studied in a flow reactor. The geometric form and size of the catalyst granules exert a pronounced effect on the apparent kinetics of the process. The highest efficiency toward phenol destruction was observed for the catalysts with a greater geometric surface area (trefoils and monolith with high channel density). The conversions of phenol and TOC at flow rate 5 mL min −1 equal to 100 and ∼90% were achieved over these catalysts. Application of the spherical shape catalyst with lowest geometric surface gave only 80% conversion of phenol at the same reaction conditions. The proposed mathematical model of the process, accounting for internal and external diffusion limitations on the base of the pseudo-first order simplification of the apparent kinetic rates, provide reasonably accurate description of the experimental data and reproducing all important process regularities.

One-pot conversion of mechanically activated cellulose to sorbitol was investigated over bifunctional catalysts based on Ru (0.6, 1 and 3 wt.%) and cesium salts of heteropoly acids (HPA) Cs2.1H0.9PW12O40 and Cs3HSiW12O40 (Cs-PW and Cs-SiW, respectively). The maximal yield of sorbitol equal to 59 % and selectivity 94 % were achieved over the 1%Ru/Cs3HSiW12O40 catalyst. Physicochemical and catalytic data showed that the rate-determining step, i.e. the hydrolysis of cellulose, depended on the surface acidity of catalysts, whereas Ru content in catalyst affected both the hydrolysis and the hydrogenation steps. The kinetic parameters for one-pot conversion of cellulose were determined by mathematical modeling approach and were successfully used for the prediction of the yields of sorbitol and mannitol.

Colloidal catalysts for oxidation of water to dioxygen, which are stable on storage and under the reaction conditions, are synthesized based on Co

Background Renewable liquid biofuel production will reduce crude oil import of India. To displace the huge quantity of fossil fuels used for energy production, this research was focused on utilization of unexploited low-cost agricultural residues for biofuel production. Corncobs are a byproduct of corn processing industry, and till now it is not utilized for biofuel production, eventhough it has high lignocellulosic concent. In this study, combined hydrodynamic cavitation and enzymatic (HCE) method was evaluated as a pretreatment method of corncob for biofuel production. The most significant process parameters namely (i) enzyme loading (3–10 U g−1), (ii) biomass loading (2.5–5.0%), and (iii) duration (5–60 min) were optimized and their effects on combined HCE pretreatment of corncob was studied through response surface methodology for lignin reduction, hemicellulose reduction and cellulose increase. Results The highest lignin reduction (47.4%) was obtained in orifice plate 1 (OP1) under the optimized conditions namely biomass loading at 5%, enzyme loading at 6.5 U g−1 of biomass, and reaction duration of 60 min. The above tested independent variables had a significant effect on lignin reduction. The cavitational yield and energy consumption under the above-mentioned optimized conditions for OP1 was 3.56 × 10−5 g J−1 and 1.35 MJ kg−1, respectively. Conclusions It is evident from the study that HCE is an effective technology and requires less energy (1.35 MJ kg−1) than other biomass pretreatment methods. Electronic supplementary material The online version of this article (10.1186/s13068-018-1204-y) contains supplementary material, which is available to authorized users.

The great potential of the catalytic biorefinery makes it practical for the substitution of renewable plant biomass for fossil feedstocks in new and traditional technologies. The scientific and commercial interest in the biorefinery concept has grown rapidly in the XXI century. The present Chapter is an overview of prospective catalysts and catalytic processes for valorization of plant biomass. There are three parts in the Chapter. Part 1 is a brief description of the composition and properties of the three most important components of plant biomass (cellulose, hemicelluloses and lignin). Part 2 gives insights into thermochemical and liquid-phase (more details are given in Chapter 3) processes for lignocellulose decomposition to produce bio-products (biochar, bio-oil and biogas) and platform molecules that are capable of replacing fossil raw materials (coal, oil and natural gas). Special emphasis is placed on pyrolysis, liquefaction and gasification, which transform lignocellulose into bio-oil and synthesis gas, as the methods for thermochemical depolymerization. Liquid-phase depolymerization of polysaccharides combined with dehydration, reduction, hydrogenolysis and oxidation in one-pot processes, as well as aqueous-phase reforming and biomass delignification, are discussed. Part 3 describes transformations of the main biomass-derived semi-products (syngas, bio-oil, sugars, furfurals and levulinic acid) to fuels or chemicals. Ready-to-use and promising methods for catalytic and biotechnological upgrading of bio-products to fuels and chemicals are considered.

Solid acid catalysts with their advantages such as easy separation, reusability, and high activity have great potentialities in the efficient depolymerization of lignocellulose to valuable chemicals. This Chapter is an overview of the main types of solid acid catalysts for biomass depolymerization. Under consideration are ion-exchange resins, carbons, zeolites, oxides, and heteropoly acids. The main focus is on transformations of polysaccharides (cellulose and hemicelluloses). The carbon catalysts and ion-exchange resins seem to be the most promising catalysts for the depolymerization. They provide the highest yields of monomer products from plant polymers. On the other hand, zeolites and some oxides are extremely stable and applicable under very severe conditions. Some aspects of the mechanism of interaction between the solid lignocellulose substrate and solid acid catalysts are discussed. Efficient transformation of lignocellulose components is shown to need some preactivation procedures. The main types of auxiliary physical and chemical methods for pretreatment of lignocellulose to partly destroy the structure and separate the components of lignocellulose are considered.

The harnessing of biocatalysts from extreme environment hot spring niche for biomass conversion is significant and promising owing to the special characteristics of extremozymes attributed by intriguing biogeochemistry and extreme conditions of these environments. Hence, in the present study 38 bacterial isolates obtained from hot springs of Manikaran (~ 95 °C), Kalath (~ 50 °C) and Vasist (~ 65 °C) of Himachal Pradesh were screened for glycosyl hydrolases by in situ enrichment technique using lignocellulosic biomass (LCB). Based on their hydrolytic potential 5 isolates were selected and they were Bacillus tequilensis (VCB1, VCB2 and VSDB4), and B. licheniformis (KBFB2 and KBFB3). Cellulolytic activity assayed by growth under submerged fermentation showed that B. tequilensis VCB1 had maximum FPA activity (3.38 IU ml−1) in 48 h, while B. licheniformis KBFB3 excelled for endoglucanase (EGA of 4.81 IU ml−1 in 24 h) and cellobiase (0.71 IU ml−1 in 48 h) activities. Among all the thermophilic biocatalysts evaluated, highest exoglucanase (0.06 IU ml−1) activity was observed in B. tequilensis VSDB4 while endoglucanase of B. licheniformis KBFB3 showed optimum specific activity at pH 7 and 70 °C. Further, the presence of celS, celB and xlnB genes in the isolates suggest their possible role in biomass conversion. Protein profiling by SDS-PAGE analysis revealed that cellulase isoforms migrated with molecular masses of 75 kDa. The endoglucanase activity of promising strain B. licheniformis KBFB3 was enhanced in the presence of Ca2+, mercaptoethanol and sodium hypochlorite whereas moderately inhibited by Cu2+, Zn2+, urea, SDS and H2O2. The results of this study indicate scope for the possible development of novel biocatalysts with multifunctional thermostable glycosyl hydrolases from hot springs for efficient hydrolysis of the complex lignocellulosic biomass into simple sugars and other derived bioproducts leading to biomass valorization. Electronic supplementary material The online version of this article (10.1186/s13568-018-0690-4) contains supplementary material, which is available to authorized users.

The catalytic properties of 1 wt % Ru catalysts with the same mean Ru cluster size of 1.4–1.5 nm supported on herringbone-type carbon nanofibers with different N contents were compared for H2 production from formic acid decomposition. The Ru catalyst on the support with 6.8 wt % N gave a 1.5–2 times higher activity for the dehydrogenation reaction (CO2, H2) than the catalyst on the undoped support. The activity in the dehydration reaction (CO, H2O) was the same. As a result, the selectivity to H2 increased significantly from 83 to 92 % with N-doping, and the activation energies for both reactions were close (55–58 kJ mol−1). The improvement could be explained by the presence of Ru clusters stabilized by pyridinic N located on the open edges of the external surface of the carbon nanofibers. This N may activate formic acid by the formation of an adduct (>NH+HCOO−) followed by its dehydrogenation on the adjacent Ru clusters.

The peroxide oxidation of model substrates (formic acid and phenol) was studied in the presence of copper- and iron-containing catalysts (0.5 % Cu–ZSM-5-30 and 0.65 % Fe–ZSM-5-30). The aim was to develop optimal kinetic models for describing the kinetics of peroxide oxidation. The real kinetics of phenol and formic acid oxidation in the presence of these catalysts at varied reaction parameters (concentrations and temperature) was studied. The copper-containing catalysts were more active to formic acid oxidation than the iron-containing catalyst over all the temperature range studied. The rate of destruction of pollutants decreases with a decrease in the H2O2 concentration and the catalyst weight. The observed rate dependences on the initial substrate concentration appeared to be different for the substrate used. With formic acid, an increase of initial concentration leads to a slight increase in the reaction rate. In the case of phenol peroxide oxidation, the negative order with respect to the substrate concentration was observed. This may be explained by strong inhibition of the reaction rates by phenol and intermediates (hydroquinone, catechol, etc.) of its oxidation. The mathematical modeling of the kinetics was performed for various types of kinetic equations that correspond to different hypotheses on the kinetic reaction scheme. The selected kinetic models based on logical kinetic schemes allowed describing the peroxide oxidation of model substrates at an appropriate accuracy.

This study used geological, geochemical, and microbiological data to examine the Uzon oils and conditions within the Uzon caldera. The trace-element compositions of crude oils and solutions from boreholes and hydrothermal springs were determined by ICP-MS. The majority of hydrothermal manifestations within the Uzon caldera are controlled by three trends of faults. The major fault zone, trending nearly E–W, is located between Kikhpinych and Taunshits volcanoes. It acts as a magma conduit and hosts numerous oval-shaped hydrothermal vents. The Oil site is situated on the periphery of the hottest area of highest hydrothermal activity within the Eastern thermal field. On the Eh–pH diagram, most solutions of the Uzon caldera define distinct fields and trends which correlate with the stability fields for sulfur and iron. The Oil site is characterized by very wide variations in temperature and Eh–pH parameters of pore solutions. The geochemical signatures of the solutions at this site are broadly similar to those from other areas of the Uzon caldera, but differ in their sulfide ion and sulfate ion concentrations. These differences can be explained by mixing of deep chloride-sodium hydrothermal solutions and solutions produced during surface oxidation of sulfide-containing material. With respect to the average continental crust, the Uzon oil is enriched in S, As, and Hg. The crude oil and solutions have broadly similar concentrations of B, S, Cl, As, Se, Br, Cd, I, Hg, and Pb and highly variable concentrations of Ti, V, Cr, Co, Ni, Cu, Cd, Nb, and Sn. The community structure of archaeal assemblages in springs and test pits at the Eastern thermal field was analyzed by 16S rRNA library and pyrosequencing methods. It was found that the proportion of archaea in the microbial communities of the Uzon caldera ranges from 2 to over 70% of the total sequences identified. Crenarchaeota were found in large proportions in all samples except one. The majority of the sequences in four samples were affiliated with Euryarchaeota, which comprise methanogenic archaea, extreme halophiles, and some extreme thermophiles. The results of geological, mineralogical-geochemical, microbiological and physicochemical studies of oil seeps in the Uzon caldera reveal distinctive geochemical characteristics of crude oil and the complexity of oil formation.

The formation of the O O bond in the water oxidation catalyzed by the iron hydroxides was modeled with the Fe 4 O 4 (OH) 4 and Fe 2 O 2 (OH) 4 complexes by means of the density functional theory. Consideration of the local minima and transition states for various routes of the association of oxo- and hydroxo-centers reveals a determinative role of the oxyl radical center Fe III O − in facilitating this process. The preferable scenario comprises two steps: (1) the abstraction of the electron and proton from the initial complex leaving behind a ferryl FeO group, and (2) the incorporation of ferryl oxygen into the tetramer edge to form peroxo group.

More than 20,000 lakes with sapropel sediments are located in southern West Siberia. The work is aimed at an integrated geochemical study of ten sapropel lake systems: a geochemical description of the lake waters, hydrobiological analysis, and analysis of the sapropels (phase and chemical analyses of inorganic matter and elemental analysis of organic matter). The geochemical landscape and low-flow regime of the waters of Siberian small lakes favor massive growth of living organisms. The anaerobic medium at the water/sediment boundary promotes the burial of organic matter as terrigenous material builds up. Based on the results, the sapropels are classified by chemical and mineral compositions into organic, organic siliceous, organic carbonate, organic carbonate-siliceous, and carbonate-siliceous. The sapropels inherit the contents of elements in soils and parental rocks, but the presence of considerable amounts of organic matter in the sediment determines their lower contents with respect to those in the soils of water catchment areas (except U, Cd, Hg, Ca, Sr, and Mn). Biochemical formation of pyrite and calcite is observed in the lake bottom sediments. The calcite formation in the sapropel sediments of Lakes Barchin, Bergul’, Kankul’, and Itkul’ determines their high Ca, Sr, Mn, and Mg contents. Comparison of data on the anion composition of the waters and the organic and mineral compositions of the sapropels has shown that the formation of low-ash biogenic sapropel takes place in lakes whose waters contain a considerable amount of dissolved organic matter and in which HCO3− is a predominant anion. No effect of the cation composition of the waters (Na, Ca, and Mg) on the sapropel composition has been detected. Therefore, Lakes Kankul’, Kachkul’nya, Bergul’, Barchin, and Kambala are the sapropel lake systems with the highest potential.

Possible ways of abiotic catalytic synthesis of biologically significant aldopentoses (ribose, xylose, arabinose, lyxose) from elementary substrates, i.e., formaldehyde (FA) and glycolaldehyde (GA) in aqueous solutions are discussed. Conditions in which the process of synthesis of pentoses yields up to 65% relative to the initial concentration of GA: homogeneous borate catalyst NaOH + H3BO3, pH 9, [GA]0 5 mM, [FA]0 50–100 mM have been found.

The catalytic behavior of different Cu(Fe)/zeolite catalysts with the MFI morphology in wet peroxide oxidation of formic acid as a model organic substrate was thoroughly examined. The influence of the method for Cu2+ ions introduction into the zeolite matrix, Cu loading and the electron state of Cu on catalytic properties of zeolites, including their stability to leaching of Cu was studied. Cu-substituted ZSM-5 zeolites with the atomic ratio Si/Al = 30 and Cu content of 0.5–1.5, which were prepared by ion exchange, were shown most promising for wet peroxide oxidation. The impact of temperature, initial pH and concentrations of reagents on the catalytic performance of the catalyst with the optimal composition also was studied. The characterization of fresh and spent catalysts using UV–vis DR and ESR spectroscopic techniques led to suppose that the high efficiency of Cu-ZSM-5 to redox reactions in aqueous media is provided by nanostructured square-planar copper oxide clusters localized in the zeolite channels.

Aerobic oxidation of glucose in the presence of Au/Al 2 O 3 catalysts with different dispersion of supported gold and Au/C catalysts containing highly dispersed gold nanoparticles was studied at varied glucose:Au molar ratios. The studies were focused on determining the contribution of the mass-transfer processes to the overall reaction kinetics in different regimes. The Au/Al 2 O 3 catalysts were more active than the Au/C catalysts at high glucose:Au molar ratios. Among the alumina-supported catalysts with different metal dispersion, the highest TOF at high glucose:Au molar ratios was characteristic of the Au/Al 2 O 3 catalysts bearing metal particles of 1–5 nm in size. Under these conditions, the high effectiveness factor of the Au/Al 2 O 3 catalysts (>95%) was observed at a uniform gold distribution through the support granules. For the Au/C catalysts with the non-uniform distribution of gold nanoparticles through the catalyst grains, the apparent reaction rate was affected by internal diffusion (the effectiveness factor of a catalyst grain is ca. 70%), while the interface gas–liquid–solid oxygen transfer influenced the overall reaction kinetics as well. At a low glucose:Au molar ratio the reaction rate was limited by oxygen dissolution in the aqueous phase. In this mass transfer regime the rate of glucose oxidation over the carbon-supported catalysts exceeds the reaction rate over the alumina-supported catalyst, which is attributed to a higher adhesion of the hydrophobic carbon support to the gas–liquid interface facilitating the oxygen mass transfer towards catalytic sites.

This article presents the first systematic study concerning the effect of the oxidative treatment conditions on the surface chemical composition and the catalytic properties in the deep wet oxidation of organic ecotoxicants of a Sibunit type carbon material (S4) which was earlier identified as promising for the oxidative treatment of industrial wastewaters. The influence of the surface chemistry of the carbon materials oxidized under different conditions on the catalytic performances in the wet air oxidation of phenol of the bare carbon materials as well as the ruthenium-containing catalysts (3 wt % Ru) supported on the oxidized carbon samples was studied. The catalytic activity of the bare carbon samples appeared to be moderate and either (i) increased with the total number of carbonyl and phenolic surface groups or (ii) decreased with the total concentration of surface carboxylic and lactonic species. However, the catalytic performances of the Ru-containing catalysts were significantly higher. Based on our results, an optimum pretreatment of the carbon support could be identified to obtain the most stable and active Sibunit-supported ruthenium catalysts in the wet air oxidation of phenols.

Numerous bitter lakes, largely closed and shallow, are concentrated in a small area of the South of Western Siberia (Kulunda and Barabinsk steppes). Most lakes are marked by the development of thick black or grayish blue silt organogenic sediments formed due to the dying-off of local halophilic organisms. Salt lakes are of great interest for scientists. The investigation was conducted in the context of complex biological and biochemical studies aimed at identifying regularities in the redistribution of elements between components of a salt-lake system by SR-XRF (Synchrotron Radiation X-ray Fluorescence).

In this study, a combination of catalytic and biotechnological processes was proposed for the first time for application in a cellulose biorefinery for the production of 5-hydroxymethylfurfural (5-HMF) and bioethanol. Hydrolytic dehydration of the mechanically activated microcrystalline cellulose over a carbon-based mesoporous Sibunt-4 catalyst resulted in moderate yields of glucose and 5-HMF (21.1-25.1 and 6.6-9.4 %). 5-HMF was extracted from the resulting mixture with isobutanol and subjected to ethanol fermentation. A number of yeast strains were isolated that also revealed high thermotolerance (up to 50 °C) and resistance to inhibitors found in the hydrolysates. The strains Kluyveromyces marxianus C1 and Ogataea polymorpha CBS4732 were capable of producing ethanol from processed catalytic hydrolysates of cellulose at 42 °C, with yields of 72.0±5.7 and 75.2±4.3 % from the maximum theoretical yield of ethanol, respectively.