- Improved xylitol production from d-arabitol by enhancing the coenzyme regeneration efficiency of the pentose phosphate pathway in Gluconobacter oxydans
-
Gluconobacter oxydans is used to produce xylitol from d-arabitol. This study aims to improve xylitol production by increasing the coenzyme regeneration efficiency of the pentose phosphate pathway in G. oxydans. Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) were overexpressed in G. oxydans. Real-time PCR and enzyme activity assays revealed that G6PDH/6PGDH activity and coenzyme regeneration efficiency increased in the recombinant G. oxydans strains. Approximately 29.3 g/L xylitol was obtained, with a yield of 73.2%, from 40 g/L d-arabitol in the batch biotransformation with the G. oxydans PZ strain. Moreover, the xylitol productivity (0.62 g/L/h) was 3.26-fold of the wild type strain (0.19 g/L/h). In repetitive batch biotransformation, the G. oxydans PZ cells were used for five cycles without incurring a significant loss in productivity. These results indicate that the recombinant G. oxydans PZ strain is economically feasible for xylitol production in industrial bioconversion.
- Li, Sha,Zhang, Jinliang,Xu, Hong,Feng, Xiaohai
-
-
Read Online
- Synthesis of xylitol by reduction of xylulose with the combination of hydrogenase and xylulose reductase
-
Xylitol synthesis by reduction of xylulose was performed by the combination of NADH regeneration system and xylulose reductase. The conversion of xylulose to xylitol was 98% after 34 h and the turnover number of NAD was 1017.
- Hasumi, Fumihiko,Teshima, Chitoku,Okura, Ichiro
-
-
Read Online
- Novel enzymatic method for the production of xylitol from D-arabitol by Gluconobacter oxydans.
-
Microorganisms capable of producing xylitol from D-arabitol were screened for. Of the 420 strains tested, three bacteria, belonging to the genera Acetobacter and Gluconobacter, produced xylitol from D-arabitol when intact cells were used as the enzyme source. Among them, Gluconobacter oxydans ATCC 621 produced 29.2 g/l xylitol from 52.4 g/l D-arabitol after incubation for 27 h. The production of xylitol was increased by the addition of 5% (v/v) ethanol and 5 g/l D-glucose to the reaction mixture. Under these conditions, 51.4 g/l xylitol was obtained from 52.4 g/l D-arabitol, a yield of 98%, after incubation for 27 h. This conversion consisted of two successive reactions, conversion of D-arabitol to D-xylulose by a membrane-bound D-arabitol dehydrogenase, and conversion of D-xylulose to xylitol by a soluble NAD-dependent xylitol dehydrogenase. Use of disruptants of the membrane-bound alcohol dehydrogenase genes suggested that NADH was generated via NAD-dependent soluble alcohol dehydrogenase.
- Suzuki, Shun-ichi,Sugiyama, Masakazu,Mihara, Yasuhiro,Hashiguchi, Ken-ichi,Yokozeki, Kenzo
-
-
Read Online
- Poly (styrene-co-divinylbenzene) amine functionalized polymer supported ruthenium nanoparticles catalyst active in hydrogenation of xylose
-
Poly (styrene-co-divinylbenzene) amine functionalized polymer supported ruthenium nanoparticles catalyst is evaluated first time in selective hydrogenation of xylose to xylitol. The catalyst Ru/PSN is characterized by different techniques such as X-ray powder diffraction, transmission electron microscopy and CO chemisorption. To develop our understanding for the activity of catalyst Ru/PSN, xylose hydrogenation experiments were carried out using catalyst of Ru/PSN with different ruthenium loading (from 1.0% to 3.0%), at different temperatures (from 100 to 140 C) and hydrogen pressures (from 30 to 55 bar). For deactivation test, the catalyst of Ru/PSN recovered from the product solution was reused up to the four times.
- Mishra, Dinesh Kumar,Dabbawala, Aasif Asharaf,Hwang, Jin- Soo
-
-
Read Online
- Catalytic hydrogenation of xylose to xylitol using ruthenium catalyst on NiO modified TiO2 support
-
The activity of Ru catalyst on a new class of NiO modified TiO2 support, Ru/(NiO-TiO2), was studied in the liquid phase catalytic hydrogenation of xylose to xylitol. The TiO2 support was modified by simple impregnation method using nickel chloride precursor and subsequent oxidation. Various catalysts with different targeted compositions of Ru (1.0 and 5.0 wt%) and NiO (1.0, 5.0 and 10 wt%) in NiO-TiO2 were prepared. These catalysts were characterized by using energy dispersive X-ray analysis (EDX/EDS), temperature-programmed reduction (TPR), inductively coupled plasma (ICP) mass spectrometry, transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and CO chemisorption. The novel catalysts are evaluated for selective hydrogenation of xylose and the results compared with those obtained from conventional Raney Ni, Ru/C and Ru/TiO2 catalysts carried out under identical reaction conditions. The effect of NiO additive in the catalyst Ru/(NiO-TiO2), clearly found to enhance the conversion, yield and selectivity to xylitol. Furthermore, the order of catalytic activity may be given as Ru (1.0%)/NiO (5.0%)-TiO2 > Ru (1.0%)/TiO2 > Ru (1.0%)/C> Raney Ni. The effects of Ru and NiO loading, xylose concentration (2.5, 15 and 30 wt%) and temperature (100, 120 and 140°C) were studied. Although at higher temp 140 °C, the conversion of xylose was increased to optimum level, xylose to xylitol selectivity decreased due to formation of by-products.
- Yadav, Mithilesh,Mishra, Dinesh Kumar,Hwang, Jin-Soo
-
-
Read Online
- Efficient D-Xylose Hydrogenation to D-Xylitol over a Hydrotalcite-Supported Nickel Phosphide Nanoparticle Catalyst
-
The hydrogenation of D-xylose is an industrially reliable method for preparing D-xylitol, which is a commonly consumed chemical. Herein, we report the highly efficient and selective hydrogenation of D-xylose to D-xylitol in water over a hydrotalcite (HT: Mg6Al2CO3(OH)16 ? 4(H2O))-supported nickel phosphide nanoparticle catalyst (nano-Ni2P/HT). The HT support drastically increased the catalytic activity of the nano-Ni2P, enabling D-xylitol synthesis under mild reaction conditions. Notably, the selective hydrogenation of D-xylose to D-xylitol proceeded even under 1 bar of H2 or at room temperature for the first time. The nano-Ni2P/HT catalyst also exhibited the highest activity among previously reported non-noble metal catalysts, with a turnover number of 960. Moreover, the nano-Ni2P/HT catalyst was reusable and applicable to a concentrated D-xylose solution (50 wt %), demonstrating its high potential for the industrial production of D-xylitol.
- Yamaguchi, Sho,Mizugaki, Tomoo,Mitsudome, Takato
-
-
Read Online
- Selective Hydrogenation of Xylose to Xylitol over Co/SiO2 Catalysts
-
Xylose can be selectively converted to xylitol in water, with an optimized yield of 98 %, in the presence of a simple silica supported monometallic cobalt – Co/SiO2 – catalyst. This catalyst displays initial outstanding catalytic properties in a proper solvent, the best results being obtained in pure water. Recyclability studies show a moderate deactivation of the catalyst, while selectivity to xylitol remains almost unchanged after 4 cycles, confirming that this catalyst formulation is very promising for the xylitol production process.
- Audemar, Ma?té,Ramdani, Wahiba,Junhui, Tang,Raluca Ifrim, Andreea,Ungureanu, Adrian,Jér?me, Fran?ois,Royer, Sébastien,de Oliveira Vigier, Karine
-
-
Read Online
- The Hofer-Moest decarboxylation of d-glucuronic acid and d-glucuronosides
-
Research was undertaken to effect the oxidative decarboxylation of glycuronosides. Experiments with free d-glucuronic acid and aldonic acids were also executed. Both anodic decarboxylation and variants of the Ruff degradation reaction were investigated. Anodic decarboxylation was found to be the only successful method for the decarboxylation of glucuronosides. It was, therefore, proposed that glycuronosides can only undergo a one-electron oxidation to form an acyloxy radical, which decomposes to form carbon dioxide and a C-5 radical, that is, a Hofer-Moest decarboxylation. The radical is subsequently oxidized to a cation by means of a second one-electron oxidation. The cation undergoes nucleophilic attack from the solvent (water), whose product (a hemiacetal) undergoes a spontaneous hydrolysis to yield a dialdose (xylo-pentodialdose from d-glucuronosides).
- Stapley, Jonathan A.,BeMiller, James N.
-
-
Read Online
- Transaldolase/glucose-6-phosphate isomerase bifunctional enzyme and ribulokinase as factors to increase xylitol production from D-arabitol in Gluconobacter oxydans
-
Xylitol production from D-arabitol by the membrane and soluble fractions of Gluconobacter oxydans was investigated. Two proteins in the soluble fraction were found to have the ability to increase xylitol production. Both of these xylitol-increasing factor
- Sugiyama, Masakazu,Suzuki, Shun-Ichi,Tonouchi, Naoto,Yokozeki, Kenzo
-
-
Read Online
- One-pot selective conversion of hemicellulose (Xylan) to xylitol under mild conditions
-
Something from nothing: Hemicellulose is selectively converted into valuable xylitol via a mild hydrogen transfer reaction, with a xylitol yield above 80%. Instead of using high-pressure H2, isopropanol is used as hydrogen source in the presence of a Ru/C catalyst. Furthermore, a selective step-by-step conversion of hemicellulose and cellulose to different polyols in a one-pot process is described. Copyright
- Yi, Guangshun,Zhang, Yugen
-
-
Read Online
- Spectroscopic characterization and cytotoxicity assessment towards human colon cancer cell lines of acylated cycloartane glycosides from Astragalus boeticus L.
-
In several European countries, especially in Sweden, the seeds of the species Astragalus boeticus L. were widely used as coffee substitutes during the 19th century. Nonetheless, data regarding the phytochemistry and the pharmacological properties of this species are currently extremely limited. Conversely, other species belonging to the Astragalus genus have already been extensively investigated, as they were used for millennia for treating various diseases, including cancer. The current work was addressed to characterize cycloartane glycosides from A. boeticus, and to evaluate their cytotoxicity towards human colorectal cancer (CRC) cell lines. The isolation of the metabolites was performed by using different chromatographic techniques, while their chemical structures were elucidated by nuclear magnetic resonance (NMR) (1D and 2D techniques) and electrospray-ionization quadrupole time-of-flight (ESI-QTOF) mass spectrometry. The cytotoxic assessment was performed in vitro by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays in Caco-2, HT-29 and HCT-116 CRC cells. As a result, the targeted phytochemical study of A. boeticus enabled the isolation of three new cycloartane glycosides, 6-O-acetyl-3-O-(4-O-malonyl)-β-d-xylopyranosylcycloastragenol (1), 3-O-(4-O-malonyl)-β-d-xylopyranosylcycloastragenol (2), 6-O-acetyl-25-O-β-d-glucopyranosyl- 3-O-β-d-xylopyranosylcycloastragenol (3) along with two known compounds, 6-O-acetyl-3-O-β-d-xylopyranosylcycloastragenol (4) and 3-O-β-d-xylopyranosylcycloastragenol (5). Importantly, this work demonstrated that the acetylated cycloartane glycosides 1 and 4 might preferentially inhibit cell growth in the CRC cell model resistant to epidermal growth factor receptor (EGFR) inhibitors.
- Graziani, Vittoria,Esposito, Assunta,Scognamiglio, Monica,Chambery, Angela,Russo, Rosita,Ciardiello, Fortunato,Troiani, Teresa,Potenza, Nicoletta,Fiorentino, Antonio,D'Abrosca, Brigida
-
-
Read Online
- Ru/TiO2-catalysed hydrogenation of xylose: The role of the crystal structure of the support
-
Effective dispersion of the active species over the support almost always guarantees high catalytic efficiency. To achieve this high dispersion, a favourable interaction of the active species with the support is crucial. We show here that the crystal structure of the titania support determines the interaction and consequently the nature of ruthenium particles deposited on the support. Similar crystal structures of RuO2 and rutile titania result in a good lattice matching and ensure a better interaction during the heating steps of catalyst synthesis. This helps maintain the initial good dispersion of the active species on the support also in the subsequent reduction step, leading to better activity and selectivity. This highlights the importance of understanding the physico-chemical processes during various catalyst preparation steps, because the final catalyst performance often depends on the type of intermediate structures formed during the preparation.
- Hernandez-Mejia, Carlos,Gnanakumar, Edwin S.,Olivos-Suarez, Alma,Gascon, Jorge,Greer, Heather F.,Zhou, Wuzong,Rothenberg, Gadi,Raveendran Shiju
-
-
Read Online
- A unique xylose reductase from Thermomyces lanuginosus: Effect of lignocellulosic substrates and inhibitors and applicability in lignocellulosic bioconversion
-
In this study, the xylose reductase gene (XRTL) from Thermomyces lanuginosus SSBP was expressed in Pichia pastoris GS115 and Saccharomyces cerevisiae Y294. The purified 39.2 kDa monomeric enzyme was optimally active at pH 6.5 and 50 °C and showed activity over a wide range of temperatures (30–70 °C) and pH (4.0–9.0), with a half-life of 1386 min at 50 °C. The enzyme preferred NADPH as cofactor and showed broad substrate specificity. The enzyme was inhibited by Cu2+, Fe2+ and Zn2+, while ferulic acid was found to be the most potent lignocellulosic inhibitor. Recombinant S. cerevisiae with the XRTL gene showed 34% higher xylitol production than the control strain. XRTL can therefore be used in a cell-free xylitol production process or as part of a pathway for utilization of xylose from lignocellulosic waste.
- Zhang, Meng,Puri, Adarsh Kumar,Wang, Zhengxiang,Singh, Suren,Permaul, Kugen
-
-
Read Online
- Ce promoted Cu/γ-Al2O3 catalysts for the enhanced selectivity of 1,2-propanediol from catalytic hydrogenolysis of glucose
-
Ce promoted Cu/γ-Al2O3 catalysts were prepared with varying amounts of Cu (x = 0–10 wt%) and Ce (y = 0–15 wt%). The prepared catalysts were characterized and tested for the conversion of aqueous glucose (5 wt%) to 1,2-propanediol in a batch reactor. 10%Ce-8%Cu/γ-Al2O3 showed the complete conversion of glucose with 62.7% selectivity of 1,2-propanediol and total glycols (1,2-propanediol, ethylene glycol & 1,2-butanediol) of 81% at milder reaction conditions. Cu facilitated the hydrogenation activity and Ce loading optimize the acid/base sites of Cu/γ-Al2O3 which obtain high selectivity of 1, 2-propanediol. Catalyst reusability is reported.
- Balachandran Kirali, Arun Arunima,Marimuthu, Banu,Sreekantan, Sreejith
-
-
- Efficient Synthesis of Sugar Alcohols over a Synergistic and Sustainable Catalyst
-
A series of catalysts were prepared for sugar alcohols production to overcome the deficiencies of the previous reported catalysts, such as low yield of sugar alcohols, single function, instability, and controversial role of active sites. The role of each metal and their synergistic-cooperation was discussed in detail with a combination of conditional experiments and characterizations. The results indicated that bifunctional Ni6.66Fe1Al1.55 catalyst has unique structure with superparamagnetism and excellent activity. The (111) and (200) planes of metallic Ni are the hydrogenation active phases and preferentially exposed on Ni-Al-Ox spinel. The desired arabitol or mannitol was obtained by tuning the ratio of Br?nsted and Lewis acid sites. The recycling tests indicated that the unique structure of the prepared Ni-based catalyst can suppress leaching and poisoning, which has high textural stability and activity.
- Lin, Lu,Qiu, Jiarong,Sun, Yong,Tang, Xing,Zeng, Xianhai,Zhang, Liangqing
-
p. 2467 - 2476
(2021/07/16)
-
- Elucidating the effect of solid base on the hydrogenation of C5 and C6 sugars over Pt–Sn bimetallic catalyst at room temperature
-
Conversion of sugars into sugar alcohols at room temperature with exceedingly high yields are achieved over Pt–Sn/γ-Al2O3 catalyst in the presence of calcined hydrotalcite. pH of the reaction mixture significantly affects the conversion and selectivity for sugar alcohols. Selection of a suitable base is the key to achieve optimum yields. Various solid bases in combination with Pt–Sn/γ-Al2O3 catalysts were evaluated for hydrogenation of sugars. Amongst all combinations, the mixture (1:1 wt/wt) of Pt–Sn/γ-Al2O3 and calcined hydrotalcite showed the best results. Hydrotalcite helps to make the pH of reaction mixture alkaline at which sugar molecules undergo ring opening. The sugar molecule in open chain form has carbonyl group which can be polarized by Sn in Pt–Sn/γ-Al2O3 and Pt facilitates the hydrogenation. In the current work, effect of both; solid base and Sn as a promoter has been studied to improve the yields of sugar alcohols from various C5 and C6 sugars at very mild reaction conditions.
- Tathod, Anup P.,Dhepe, Paresh L.
-
supporting information
(2021/05/19)
-
- Unexpected reactivity related to support effects during xylose hydrogenation over ruthenium catalysts
-
Xylose is a major component of hemicelluloses. In this paper, its hydrogenation to xylitol in aqueous medium was investigated with two Ru/TiO2catalysts prepared with two commercial TiO2supports. A strong impact of the support on catalytic performance was evidenced. Ru/TiO2-R led to fast and selective conversion of xylose (100% conversion in 2 h at 120 °C with 99% selectivity) whereas Ru/TiO2-A gave a slower and much less selective transformation (58% conversion in 4 h at 120 °C with 17% selectivity) with the formation of several by-products. Detailed characterization of the catalysts with ICP, XRD, FTIR, TEM, H2chemisorption, N2porosimetry, TPR and acid-base titration was performed to elucidate the role of each support. TiO2-R has a small specific surface area with large ruthenium nanoparticles in weak interaction with the TiO2support and no acidity, whereas TiO2-A is a mesoporous material with a large specific surface area that is mildly acidic, and bears small ruthenium particles in strong interaction with the TiO2support. The former was very active and selective for xylose hydrogenation to xylitol whereas the latter was less active and poorly selective. Moreover, careful analysis of the reaction products also revealed that anatase TiO2can catalyze undesired side-reactions such as xylose isomerisation to various pentoses, and therefore the corresponding unexpected polyols (arabitol, ribitol) were produced during xylose conversion by hydrogenation. In a first kinetic approach, a simplified kinetic model was built to compare quantitatively intrinsic reaction rates of both catalysts. The kinetic constant for hydrogenation was 20 times higher for Ru/TiO2-R at 120 °C.
- Fongarland, Pascal,Freitas, Victoria D. S.,Paez, Ana,Philippe, Régis,Veyre, Laurent,Vilcocq, Léa
-
p. 39387 - 39398
(2021/12/27)
-
- Photocatalytic Conversion of Xylose to Xylitol over Copper Doped Zinc Oxide Catalyst
-
Abstract: In the present investigation, photocatalytic conversion of xylose by Copper (Cu) doped Zinc oxide (ZnO) was investigated under Ultraviolet Light emitting diode (UVA-LED) illumination. Photocatalysts were synthesized successfully by chemical prec
- Rohini,Hebbar, H. Umesh
-
p. 2583 - 2594
(2021/02/05)
-
- Modulating Electrostatic Interactions in Ion Pair Intermediates To Alter Site Selectivity in the C?O Deoxygenation of Sugars
-
Controlling which products one can access from the predefined biomass-derived sugars is challenging. Changing from CH2Cl2 to the greener alternative toluene alters which C?O bonds in a sugar are cleaved by the tris(pentafluorophenyl)borane/HSiR3 catalyst system. This increases the diversity of high-value products that can be obtained through one-step, high-yielding, catalytic transformations of the mono-, di-, and oligosaccharides. Computational methods helped identify this non-intuitive outcome in low dielectric solvents to non-isotropic electrostatic enhancements in the key ion pair intermediates, which influence the reaction coordinate in the reactivity-/selectivity-determining step. Molecular-level models for these effects have far-reaching consequences in stereoselective ion pair catalysis.
- Bowers, Bekah E.,Gagné, Michel R.,Lowe, Jared M.,Seo, Youngran
-
supporting information
p. 17297 - 17300
(2020/07/30)
-
- Harnessing the reactivity of poly(methylhydrosiloxane) for the reduction and cyclization of biomass to high-value products
-
Poly(methylhydrosiloxane) (PMHS) has been examined for its ability to reduce and subsequently cyclize carbohydrate substrates using catalytic tris(pentafluorophenyl)borane (BCF). The work herein is the first reported example of the direct conversion of monosaccharides to 1,4-anhydro and 2,5-anhydro products utilizing a hydrosiloxane reducing agent. PMHS is produced from waste products of the silicone industry, making it a green alternative to traditional hydrosilane reducing agents. This work thus contributes to the goal of utilizing renewable feedstocks in the production of fine-chemicals.
- Hein, Nicholas M.,Seo, Youngran,Lee, Stephen J.,Gagné, Michel R.
-
supporting information
p. 2662 - 2669
(2019/06/13)
-
- Controlling Sugar Deoxygenation Products from Biomass by Choice of Fluoroarylborane Catalyst
-
The feedstocks from biomass are defined and limited by nature, but through the choice of catalyst, one may change the deoxygenation outcome. We report divergent but selective deoxygenation of sugars with triethylsilane (TESH) and two fluoroarylborane catalysts, B(C6F5)3 and B(3,5-CF3)2C6H3)3 (BAr3,5-CF3). To illustrate, persilylated 2-deoxyglucose shows exocyclic C-O bond cleavage/reduction with the less sterically congested BAr3,5-CF3, whereas endocyclic C-O bond cleavage/reduction predominates with the more Lewis acidic B(C6F5)3. Chiral furans and linear polyols can be selectively synthesized depending on the catalysts. Mechanistic studies demonstrate that the resting states of these catalysts are different.
- Seo, Youngran,Lowe, Jared M.,Gagné, Michel R.
-
p. 6648 - 6652
(2019/08/26)
-
- Effect of Cu addition to carbon-supported Ru catalysts on hydrogenation of alginic acid into sugar alcohols
-
The objective of this study was to investigate the effect of Cu addition to carbon supported Ru catalysts on the hydrogenation of macroalgae-derived alginic acid into sugar alcohols, mainly sorbitol and mannitol. Both geometric and electronic effects were determined based on results of H2-TPR, H2- or CO-chemisorption, and XPS analyses after Cu was added to Ru. The addition of Cu to Ru caused blocking of active Ru surface and electron transfer between Ru and Cu. The intimate interaction between Ru and Cu formed RuCu bimetallic clusters which expedited hydrogen spillover from Ru to Cu. The highest yield of target sugar alcohols of 47.4% was obtained when 5 wt% of Ru and 1 wt% of Cu supported on nitric acid-treated activated carbon reacted at 180 °C for 2 h. The RuCu bimetallic catalyst exhibited deactivation upon repeated reactions due to the carbon deposition on the catalyst.
- Ban, Chunghyeon,Yang, Seungdo,Kim, Hyungjoo,Kim, Do Heui
-
-
- Method for preparing sugar alcohol and coproducing white carbon black
-
The invention relates to a method for preparing sugar alcohol and coproducing white carbon black. The method comprises the following steps: mixing raw sugar and a water-soluble strong alkali solution;adding silicon and a catalyst; removing oxygen and stirring and reacting at 100 to 200 DEG C under a sealed state; filtering to obtain filtrate C and filtering residue D; adding acid into the filtrate C and regulating the pH (Potential of Hydrogen); stirring and reacting, and filtering to obtain filtrate E and a solid F; drying the solid F to obtain the white carbon black; carrying out electrodialysis desalination on the filtrate E to obtain a sugar alcohol solution G; concentrating, spraying and drying the sugar alcohol solution G to obtain the sugar alcohol. According to the method providedby the invention, hydrogen gas generated through reaction of silicon and strong alkali is used as a reducing agent, and hydrogen gas does not need to be additionally introduced or other reducing agents do not need to be additionally added; unreacted substances and products can be repeatedly utilized and pollution caused by three wastes is not caused; the purity of the prepared sugar alcohol can reach 90 percent or more and the white carbon black can reach HG/T 3061-2009 A type standards.
- -
-
Paragraph 0062-0070; 0080-0088
(2018/06/04)
-
- Selective microbial production of xylitol from biomass based sugar stream with enriched pentose component
-
The present invention utilizes yeast Candida tropicalis (NRRL 12968) for xylitol production, as an alternative and unexplored strain with high bioconversion rate and stability at higher initial xylose concentration. Different parameters are optimized for batch fermentation of xylose to xylitol such as initial xylose concentration, aeration (vvm), agitation (rpm), percent inoculum addition, and oxygen transfer rate. Maximum xylitol yield of 0.7 g/g of xylose is obtained with 3.33% inoculum, 250 g/l of initial xylose concentration, 0.2 vvm of aeration rate, and two stage agitation strategy comprising of 500 rpm for 0-24 hrs and 400 rpm for 24-72 hrs at not more than 72 hrs of fermentation time. The present invention coins a novel process mode of fermentation where the batch process is extended with continuous fermentation at optimum dilution rate of 0.02/hr with effective residence time of 52 hrs. Productivity of ‘batch followed by continuous’ process is 2.5 gm/lit/hr which is 1.34 times higher than batch and/or continuous process alone.
- -
-
-
- Hydrogenolysis of sorbitol into valuable C3-C2 alcohols at low H2 pressure promoted by the heterogeneous Pd/Fe3O4 catalyst
-
The hydrogenolysis of sorbitol and various C5-C3 polyols (xylitol; erythritol; 1,2- 1,4- and 2,3-butandiol; 1,2-propandiol; glycerol) have been investigated at low molecular hydrogen pressure (5 bar) by using Pd/Fe3O4, as heterogeneous catalyst and water as the reaction medium. Catalytic experiments show that the carbon chain of polyols is initially shortened through dehydrogenation/decarbonylation and dehydrogenation/retro-aldol mechanisms followed by a series of cascade reactions that include dehydrogenation/decarbonylation and dehydration/hydrogenation processes. At 240 °C, sorbitol is fully converted into lower alcohols with ethanol being the main reaction product in liquid phase.
- Gumina, Bianca,Mauriello, Francesco,Pietropaolo, Rosario,Galvagno, Signorino,Espro, Claudia
-
p. 152 - 160
(2018/02/17)
-
- Acid catalysis dominated suppression of xylose hydrogenation with increasing yield of 1,2-pentanediol in the acid-metal dual catalyst system
-
One-pot conversion of xylose to 1,2-pentanediol was investigated in a dual catalyst system composed of Ru/C and niobium phosphate as hydrogenation and acid catalysts, respectively. A series of niobium phosphate catalysts well-characterized by XRD, N2 physisorption, FT-IR, NH3-TPD, Py-IR and XPS were tested regarding the effect of their acid properties on product selectivity for the studied process. A systematic study was reported on the effect of reaction conditions. The combined yield of 21–27% to 1,2-pentanediol and its precursor 1-hydroxyl-2-pentanone was accomplished at 423 K under 3.0 Mpa hydrogen pressure in water-γ-valerolactone/cyclohexane biphasic system. At optimized conditions, the correlation between the product yield and the surface Lewis/Br?nsted ratio were analyzed. The results revealed that the lower apparent activation energy of xylose dehydration reaction catalyzed by Lewis acid site accounted for the high product selectivity for sugar intermediate and furfural hydrogenation processes, especially for the combined selectivity to 1,2-pentanediol and 1-hydroxyl-2-pentanone. This study lays the grounds for further design of improved solid acid catalysts with high selectivity of 1, 2-pentanediol.
- Wang, Nailiang,Chen, Zhipeng,Liu, Licheng
-
-
- Ordered Mesoporous NiCeAl Containing Catalysts for Hydrogenolysis of Sorbitol to Glycols
-
Cellulose-derived sorbitol is emerging as a feasible and renewable feedstock for the production of value-added chemicals. Highly active and stable catalyst is essential for sorbitol hydrogenolysis. Ordered mesoporous M–xNiyCeAl catalysts with different loadings of nickel and cerium species were successfully synthesized via one-pot evaporation-induced self-assembly strategy (EISA) and their catalytic performance were tested in the hydrogenolysis of sorbitol. The physical chemical properties for the catalysts were characterized by XRD, N2 physisorption, H2-TPR, H2 impulse chemisorption, ICP and TEM techniques. The results showed that the ordered mesopores with uniform pore sizes can be obtained and the Ni nanoparticles around 6 nm in size were homogeneously dispersed in the mesopore channels. A little amount of cerium species introduced would be beneficial to their textural properties resulting in higher Ni dispersion, metal area and smaller size of Ni nanoparticles. The M–10Ni2CeAl catalyst with Ni and Ce loading of 10.9 and 6.3 wt % shows better catalytic performance than other catalysts, and the yield of 1,2-PG and EG can reach 56.9% at 493 K and 6 MPa pressure for 8 h after repeating reactions for 12 times without obvious deterioration of physical and chemical properties. Ordered mesoporous M–NiCeAl catalysts are active and stable in sorbitol hydrogenolysis.
- Zhou, Zhiwei,Zhang, Jiaqi,Qin, Juan,Li, Dong,Wu, Wenliang
-
p. 456 - 465
(2018/03/21)
-
- AN ECO-FRIENDLY PROCESS FOR HYDROGENATION OR/AND HYDRODEOXYGENATION OF ORGANIC COMPOUND USING HYDROUS RUTHENIUM OXIDE CATALYST
-
The invention discloses aneco-friendly process for hydrogenation (alkenealkene, carbonyl compound and aromatic) and hydrodeoxygenation (methoxy phenols) of organic compound using hydrous ruthenium oxide (HRO) and its supported form as a recyclable heterogeneous catalyst in aqueous medium with good yield of desired compounds (70-100%) under mild reaction conditions. The invention also discloses hydrogenation of organic compound such as alkene, carbonyl compound and substituted aromatic and also for the processes that involve hydrodeoxygenation, for example, lignin derived aromatic (methoxy phenols).
- -
-
Page/Page column 13; 14; 20; 21; 26
(2017/08/01)
-
- Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
-
Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
- Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
-
supporting information
p. 13757 - 13761
(2017/10/09)
-
- Boronic acid recognition of non-interacting carbohydrates for biomedical applications: Increasing fluorescence signals of minimally interacting aldoses and sucralose
-
To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed
- Resendez, Angel,Halim, Md Abdul,Singh, Jasmeet,Webb, Dominic-Luc,Singaram, Bakthan
-
p. 9727 - 9733
(2017/11/30)
-
- A using a supported metal catalyst method for preparing alcohols (by machine translation)
-
The invention provides a method for using a supported metal catalyst for producing alcohol, comprising the following steps: carbonyl-containing compounds in the supported metal catalyst under the catalytic action of, and H2 To carry out the reduction reaction, to obtain the alcohol compound; the supported metal catalyst includes: catalyst carrier, loaded on the catalyst carrier and the metal; the metal for the 8th group metal in one or more of; the catalyst carrier is zirconium oxide, lanthanide metal oxide, lanthanide metal oxide-modified zirconia, 4th cycle transition metal oxide modified zirconia, 5th cycle transition metal oxide modified zirconia, alkaline earth metal oxide modified zirconium oxide or aluminum oxide modified zirconia. This invention adopts the above-mentioned particular catalyst for producing alcohol, has high conversion rate, good selectivity, mild reaction conditions, simple device and the like, it has good industrial application prospect. (by machine translation)
- -
-
Paragraph 0056-0061
(2017/09/01)
-
- Preparation method of gamma-acetyl n-propanol
-
The invention discloses a preparation method of gamma-acetyl n-propanol. The method includes the steps of (1) adding the hydrolysate of plant fiber or xylose and other raw materials into a reaction still, adding a two-phase reactive solvent and a catalyst, inletting hydrogen, and heating the reaction still to react for several hours; (2) carrying out standing, liquid separation and then solid-liquid separation on reaction materials in the reaction still, obtaining water phase, oil phase and the catalyst, and recycling the catalyst for reutilization; (3) concentrating water phase products, extracting 1, 4-pentanediol in the oil phase, mixing with the concentrated solution, and carrying out further separation to obtain a crude product of 1, 4-pentanediol; (4) pumping the crude product of 1, 4-pentanediol obtained from the water phase and the oil phase in step (3) to a fixed bed reactor, carrying out dehydrogenation to produce gamma-acetyl n-propanol under the action of a catalytic dehydrogenation catalyst or an oxydehydrogenation catalyst. According to the preparation method, raw materials have extensive sources, the production cost is low, no inorganic acid system is used, and the reaction process is environment-friendly.
- -
-
Paragraph 0036; 0037
(2017/12/09)
-
- CTAB-assisted sol-microwave method for fast synthesis of mesoporous TiO2 photocatalysts for photocatalytic conversion of glucose to value-added sugars
-
Fabrication technique is an important factor for development of catalysts. Titanium dioxide (TiO2) is one of efficient photocatalysts. In this work, we firstly report the fabrication of TiO2 nanoparticles by sol-microwave method with cetyltrimethylammonium bromide (CTAB) surfactant. Absence of surfactant, microwave treatment significantly reduced the cluster sizes of TiO2, but high aggregations of TiO2 particles were observed. CTAB has great impact on morphology, cluster size and mesoporous structure of TiO2. Therefore, surface area of TiO2 synthesized by sol-microwave method with 0.108 M CTAB increased from 15.97 to 37.60 m2/g. Photocatalytic activity of TiO2 was tested via the glucose conversion to produce value-added chemicals (gluconic acid, xylitol, arabinose and formic acid). It was found that surface area, mesoporous structure and pore size of TiO2 are crucial properties for glucose conversion and product distribution. From the reaction test, 0.108 M CTAB/MW-TiO2 achieved the highest glucose conversion (62.28%).
- Payormhorm, Jiraporn,Chuangchote, Surawut,Laosiripojana, Navadol
-
p. 546 - 555
(2017/09/01)
-
- A one-pot method for the enhanced production of xylitol directly from hemicellulose (corncob xylan)
-
An efficient one-pot reaction system for converting hemicellulose (corncob xylan) into xylitol was developed by using a heterogeneous catalyst and water as solvent, without the presence of any acids. A xylitol yield of 46.3% was achieved after 45 min of reaction using Ru/CNT as catalyst, which showed excellent stability after repeated use. Since the conversion of hemicellulose consists of xylan hydrolysis to xylose followed by the subsequent hydrogenation to xylitol, the two steps were then evaluated separately. The effect of the presence of cellulose on the conversion of xylan and distribution of products was also studied and the yield of xylitol was increased up to around 60% in less than 1 h of reaction. Furthermore, a yield of sorbitol over 80% could also be attained in just 2 h of reaction. Being this result one of the best ever reported for the direct conversion of cellulose and hemicellulose using an environmentally friendly approach, the proposed method shows great potential for the optimization of the catalytic production of xylitol and sorbitol.
- Ribeiro, Lucília S.,Delgado, Juan J.,De Melo órf?o, José J.,Ribeiro Pereira, Manuel Fernando
-
p. 95320 - 95327
(2016/10/21)
-
- Kinetic insight into the effect of the catalytic functions on selective conversion of cellulose to polyols on carbon-supported WO3 and Ru catalysts
-
Efficient conversion of cellulose, the most abundant biomass on Earth, to chemicals in high yields remains a formidable challenge. Here, we report the marked change in the distribution of polyol products in the cellulose reaction on Ru/C and WO3/C, strongly depending on the competitive reactions of the glucose intermediate. WO3 crystallites not only promote, as a solid acid, the efficient hydrolysis of cellulose to glucose, but also catalyze the selective cleavage of the C-C bonds in glucose and other C6 sugar intermediates, leading to the formation of ethylene glycol and propylene glycol, in competition with the sugar hydrogenation to the corresponding C6 polyols (e.g. sorbitol) on Ru/C. The basic C support, behaving similar to other solid bases (i.e. MgO), catalyzes the isomerization of glucose into fructose, leading to the favored formation of propylene glycol instead of ethylene glycol. Such strong dependence of the product distribution on the catalytic functions is clarified by the kinetic analysis of the three competitive reactions of glucose, including its hydrogenation, isomerization and C-C bond cleavage. Importantly, such kinetic analysis can predict the maximum selectivity ratio of propylene glycol to ethylene glycol, which is 2.5, for example, at 478 K under the reaction conditions in this work, corresponding to a maximum yield of propylene glycol of ～71%. These understandings shed new insights into the selective conversion of cellulose, which provides guidance for the rational design of catalyst functions and tuning of reaction parameters towards the controllable synthesis of specific products from cellulose.
- Liu, Yue,Liu, Haichao
-
-
- Catalytic oxidation of cellobiose over TiO2 supported gold-based bimetallic nanoparticles
-
A series of Au-M (M = Cu, Co, Ru and Pd) bimetallic catalysts were supported on TiO2via a deposition-precipitation (DP) method, using urea as a precipitating agent. The resulting catalysts were employed in the catalytic oxidation of cellobiose to gluconic acid and the properties of these catalysts were carefully examined using various characterization techniques. Cu-Au/TiO2 and Ru-Au/TiO2 catalysts demonstrated excellent catalytic activities in the oxidation of cellobiose to gluconic acid, though with contrasting reaction mechanisms. Complete conversion of cellobiose (100%) with a gluconic acid selectivity of 88.5% at 145 °C within 3 h was observed for reactions performed over Cu-Au/TiO2; whereas, a conversion of 98.3% with a gluconic acid selectivity of 86. 9% at 145°C within 9 h was observed for reactions performed over Ru-Au/TiO2. A reaction pathway was proposed based on the distribution of reaction products and kinetic data. It is suggested that cellobiose is converted to cellobionic acid (4-O-beta-d-glucopyranosyl-d-gluconic acid) and then gluconic acid is formed through the cleavage of the β-1,4 glycosidic bond in cellobionic acid over Cu-Au/TiO2 catalysts. On the other hand, for reactions over the Ru-Au/TiO2 catalyst, glucose was observed as the reaction intermediate and gluconic acid was formed as a result of glucose oxidation. For reactions over Co-Au/TiO2 and Pd-Au/TiO2 catalysts, fructose was observed as the reaction intermediate, along with small amounts of glucose. Co and Pd remarkably promoted the successive retro-aldol condensation reactions of fructose to glycolic acid, instead of the selective oxidation to gluconic acid. This journal is
- Amaniampong, Prince Nana,Jia, Xinli,Wang, Bo,Mushrif, Samir H.,Borgna, Armando,Yang, Yanhui
-
p. 2393 - 2405
(2015/04/14)
-
- Production of xylitol from glucose by a recombinant strain
-
The present invention relates to a recombinant microbial host for the production of xylitol, the recombinant microbial host containing a nucleic acid sequence encoding a NAD+-specific D-arabitol 4-oxidoreductase (EC 1.1.1.11) using D-arabitol as substrate and producing D-xylulose as product, and a nucleic acid sequence encoding a NADPH-specific xylitol dehydrogenase using D-xylulose as substrate and producing xylitol as product.
- -
-
Paragraph 0091-0106
(2016/01/11)
-
- Manganese oxide-stabilized zirconia catalyst support materials
-
The present disclosure relates generally to catalyst support materials, catalysts and methods for using them, such as methods for converting sugars, sugar alcohols, glycerol, and bio-renewable organic acids to commercially-valuable chemicals and intermediates. One aspect of the invention is catalyst support material including ZrO2 and one or more oxides of manganese (MnOx), the catalyst support material being at least about 50 wt % ZrO2 and MnOx. In certain embodiments, the weight ratio of ZrO2 to MnOx is within the range of about 1:1 to about 30:1; and/or the catalyst support material is substantially free of any binder, extrusion aid or additional stabilizing agent.
- -
-
Page/Page column 26; 27
(2015/11/10)
-
- Selective terminal C-C scission of C5-carbohydrates
-
The selective catalytic production of C4-tetritols (erythritol and threitol) from C5-sugars is an attractive route for the conversion of non-digestible sugars to C4-building blocks from agro residues. Here we show that an unprecedented high selectivity of 20-25% C4-tertritols can be achieved under mild conditions (138 °C, 6 bar H2, and 24 h) in the aqueous conversion of xylose over a 5 wt% Ru/C catalyst. A mechanistic study revealed that the dominant reaction mechanism for C5-sugar conversion involves a formal decarbonylation step leading to the initial formation of the desired C4-tetritols. Subsequently the formed C4-tetritols undergo further terminal C-C scissions to glycerol and ethylene glycol. Remarkably, potentially competing reactions like internal C-C chain scission (fragmentation) or hydrodeoxygenation (HDO) do not occur to any significant extent under the applied conditions.
- Van Der Klis, Frits,Gootjes, Linda,Van Haveren, Jacco,Van Es, Daan S.,Bitter, Johannes H.
-
p. 3900 - 3909
(2015/07/15)
-
- Conversion of glucose and sorbitol in the presence of Ru/C and Pt/C catalysts
-
The conversion of glucose and sorbitol in the presence of Ru and Pt catalysts supported on carbon was carried out at different pressure and temperature conditions, using a batch and a semi-batch reactor. Attempts were made to improve the selectivity of glycols and alcohols (ethanol), introducing a promoter and inhibiter of the hydrogenolysis in the reactant mixture. On the basis of these results, which confirm the higher activity of Ru with respect to Pt, and the important role of an inhibitor like sulphur, the mechanism driving these reactions and the promising thermocatalytic conditions are clearer. This journal is
- Tronci, Stefania,Pittau, Barbara
-
p. 23086 - 23093
(2015/06/02)
-
- Continuous transfer hydrogenation of sugars to alditols with bioderived donors over Cu-Ni-Al catalysts
-
The transfer hydrogenation of sugars to alditols with biobased alcohol donors was studied over hydrotalcite-derived Cu6-xNixAl2 catalysts prepared by coprecipitation at different pH and featuring variable Cu/Ni ratios. Their evaluation, after in situ activation in pure H2 at 773 K, in the ethanol-assisted upgrading of glucose in a continuous-flow fixed-bed reactor identified the solid synthesized at pH 9-10 and with Cu/Ni=1 as the best performer. Based on textural, structural, and redox analyses, this is related to an enhanced intermetallic interaction. Upon screening alternative donors, a sorbitol yield as high as 67 % was achieved with 1,4-butanediol. The catalytic system displayed a stable behavior during 48 h on stream and proved suitable to hydrogenate also fructose, mannose, xylose, and arabinose to the corresponding polyols (yields up to 65 %), thus standing as a more sustainable and economical alternative to Ru-based catalysts for sugar reductive upgrading. Finding the right partner: Hydrotalcite-derived Cu-Ni-Al materials efficiently catalyze the continuous transfer hydrogenation of C6 and C5 sugars with biobased alcohols as hydrogen donors with yields of up to 67 %. This technology comprises a safer and cheaper alternative to direct hydrogenation over Ru catalysts.
- Scholz, David,Aellig, Christof,Mondelli, Cecilia,Pérez-Ramírez, Javier
-
p. 1551 - 1558
(2015/05/27)
-
- Characterization of the chemical diversity of glycosylated mycosporine-like amino acids in the terrestrial cyanobacterium Nostoc commune
-
Mycosporine-like amino acids (MAAs) are UV-absorbing pigments, and structurally unique glycosylated MAAs are found in the terrestrial cyanobacterium Nostoc commune. In this study, we examined two genotypes of N. commune colonies with different water extract UV-absorption spectra. We found structurally distinct MAAs in each genotype. The water extract from genotype A showed a UV-absorbing spectrum with an absorption maximum at 335 nm. The extract contained the following compounds: 7-O-(β-arabinopyranosyl)-porphyra-334 (478 Da), pentose-bound shinorine (464 Da), hexose-bound porphyra-334 (508 Da) and porphyra-334 (346 Da). The water extract from genotype B showed a characteristic UV-absorbing spectrum with double absorption maxima at 312 and 340 nm. The extract contained hybrid MAAs (1050 Da and 880 Da) with two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen linked to 2-O-(β-xylopyranosyl)-β-galactopyranoside. A novel 273-Da MAA with an absorption maximum at 310 nm was also identified in genotype B. The MAA consisted of a 3-aminocyclohexen-1-one linked to a γ-aminobutyric acid chain. These MAAs had potent radical scavenging activities in vitro and the results confirmed that the MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. The two genotypes of N. commune exclusively produced their own characteristic glycosylated MAAs, which supports that MAA composition could be a chemotaxonomic marker for the classification of N. commune.
- Nazifi, Ehsan,Wada, Naoki,Asano, Tomoya,Nishiuchi, Takumi,Iwamuro, Yoshiaki,Chinaka, Satoshi,Matsugo, Seiichi,Sakamoto, Toshio
-
p. 154 - 168
(2015/02/18)
-
- Solid base supported metal catalysts for the oxidation and hydrogenation of sugars
-
Pt impregnated on γ-Al2O3 (acidic support) and hydrotalcite (basic support) catalysts were synthesized, characterized and used in the oxidation and hydrogenation reactions of C5 and C6 sugars. In the absence of homogeneous base, 83% yield for gluconic acid; an oxidation product of glucose can be achieved over Pt/hydrotalcite (HT) catalyst at 50 °C under atmospheric oxygen pressure. Similarly, 57% yield for xylonic acid, an oxidation product of xylose is also possible over Pt/HT catalyst. Hydrogenation of glucose conducted using Pt/γ-Al2O3 + HT catalytic system showed 68% sugar alcohols (sorbitol + mannitol) formation. The 82% yield for C5 sugar alcohols (xylitol + arabitol) was obtained by subjecting xylose to hydrogenation over Pt/γ-Al2O3 + HT at 60 °C. UV analysis helped to establish the fact that under alkaline conditions sugars prefer to remain in open chain form in the solution and thus exposes CHO group which further undergoes oxidation and hydrogenation reactions to yield acids and alcohols.
- Tathod, Anup,Kane, Tanushree,Sanil,Dhepe, Paresh L.
-
-
- Some important catalytic challenges in the bioethanol integrated biorefinery
-
The concept of integrated biorefinery is presented and discussed. Integrated biorefineries demand the use of innovation, or rather, new chemical routes must be introduced in order to add value to intermediates and residues. The concept of integrated biorefinery is then applied to an ethanol producing facility and a flow sheet of the main catalytic routes to promote modifications of residues is proposed. CO2 and bagasse are considered the most promising residues to undergo catalytic transformations. Hydrogenation of CO2 to produce syngas/methanol is an interesting alternative to add value to this molecule. Nickel supported on a mixed oxide NiCeZr is presented as an excellent catalyst to produce syngas out of CO2. Furthermore, the potential use of two main components of bagasse, lignin and hemicellulose, is discussed, lignin being deployed as a feedstock to produce activated carbons and acidic sulfonated carbons, Acid sulfonated carbons are shown to be excellent catalysts for hydrolysis/dehydration of biomass derivatives such as polysaccharides and polyols. Moreover, activated carbons may also play an important role as outstanding supports for metal-supported catalysts, which may be used in the hydrogenation of sugars.
- Sousa-Aguiar, Eduardo Falabella,Appel, Lucia Gorenstin,Zonetti, Priscila Costa,Fraga, Adriano Do Couto,Bicudo, Alex Azevedo,Fonseca, Isabel
-
-
- Molecular analysis of NAD+-dependent xylitol dehydrogenase from the zygomycetous fungus Rhizomucor pusillus and reversal of the coenzyme preference
-
The zygomycetous fungus Rhizomucor pusillus NBRC 4578 is able to ferment not only D-glucose but also D-xylose into ethanol. Xylitol dehydrogenase from R. pusillus NBRC 4578 (RpXDH), which catalyzes the second step of D-xylose metabolism, was purified, and its enzymatic properties were characterized. The purified RpXDH preferred NAD+ as its coenzyme and showed substrate specificity for xylitol, D-sorbitol, and ribitol. cDNA cloning of xyl2 gene encoding RpXDH revealed that the gene included a coding sequence of 1,092 bp with a molecular mass of 39,185 kDa. Expression of the xyl2 in R. pusillus NBRC 4578 was induced by D-xylose, and the expression levels were increased with accumulation of xylitol. The xyl2 gene was expressed in Escherichia coli, and coenzyme preference of the recombinant RpXDH was reversed from NAD+ to NADP+ in the double mutant D205A/I206R by site-directed mutagenesis.
- Yamasaki-Yashiki, Shino,Komeda, Hidenobu,Hoshino, Kazuhiro,Asano, Yasuhisa
-
p. 1943 - 1953
(2015/08/18)
-
- Towards efficient synthesis of sugar alcohols from mono- and poly-saccharides: Role of metals, supports & promoters
-
Biomass derived sugar alcohols (xylitol, arabitol) find numerous uses in the food, oral hygiene and pharmaceutical industries. Their direct synthesis from poly-saccharides, however, still remains an immense challenge. In this study, we demonstrate in detail the effects of metals, supports and promoters in enhancing the yields of sugar alcohols from mono- and poly-saccharides. We undertook synthesis of bimetallic catalysts, M-M′/S (M, metal = Pt, Ru; M′, promoter = Sn, Ga, Fe; S, support = γ-Al2O3 (AL), SiO2-Al2O3 (SA), carbon (C)) with varying metal loadings (Pt/Ru = 2, 3.5 wt%; Sn = 0.22, 0.43, 0.87, 1.5, 3.5 wt%; Ga/Fe = 0.25 wt%) by a co-impregnation method. The catalytic activities of these catalysts were evaluated in the synthesis of sugar alcohols from xylose (mono-saccharide) and hemicellulose (xylan, poly-saccharide) at 130-190 °C. Among all of the bimetallic catalysts, the Pt(3.5)Sn(0.43)/AL catalyst (50%) showed 2.8 times improvement in the yield of sugar alcohols compared to a monometallic Pt(3.5)/AL catalyst (18%). Similarly, in the xylose reaction a 2.4 times enhancement in the yield of sugar alcohols over Pt(3.5)Sn(0.43)/AL (79%) was observed compared to the 33% yield obtained with Pt(3.5)/AL. By conducting several experiments it is confirmed that the residual Cl-, which remained on the catalyst even after calcinations and reductions carried out at 400 °C, does not play any role in catalysis. The stability of the Pt(3.5)Sn(0.43)/AL catalyst confirmed by XRD and ICP analysis was responsible for achieving reproducible activity in at least 5 consecutive runs. Formation of electron deficient Sn confirmed by XPS analysis helped to polarize the carbonyl group, which in turn enhanced the sugar alcohols' yields. Formation of PtSn and Pt3Sn species was observed when Sn loading was more than 0.87%.
- Tathod, Anup P.,Dhepe, Paresh L.
-
p. 4944 - 4954
(2015/01/08)
-
- New 9,19-cycloartenol glycosides isolated from the roots of Cimicifuga simplex and their anti-inflammatory effects
-
Two new cycloartenol triterpene saponins, 3β,16α-dihydroxy-12-acetoxy-16,22-cyclo-23-ketone-24R,25-epoxy-cycloartane-3-O-β-d-galactopyranoside (1), 3β,16α-dihydroxy-12-acetoxy-16,22-cyclo-23-ketone-24R,25-epoxy-cycloartane-7-ene-3-O-β-d-xylopyranoside (2), were isolated from the ethyl acetate soluble fraction of the roots of Cimicifuga simplex Wormsk. Their structures were established by detailed spectroscopic analysis, including extensive 2D NMR data. Their anti-proinflammatory activities were also carried out by LPS-stimulated IL-6, IL-23 and TNF-α genes expression in RAW cells in vitro using Q-PCR method.
- Su, Yang,Wu, Lun,Wang, Qiuhong,Yang, Bingyou,Kuang, Haixue
-
supporting information
p. 5688 - 5691
(2015/01/08)
-
- Selective conversion of microcrystalline cellulose into hexitols over a Ru/[Bmim]3PW12O40 catalyst under mild conditions
-
A catalyst consisting of dispersed Ru on an ionic liquid (BmimPF 6)-heteropolyacid (H3PW12O40· nH2O) hybrid as a support, i.e. Ru/[Bmim]3PW 12O40, has been successfully synthesized. The catalyst, which combines the Ru sites for hydrogenation and both Lewis and Br?nsted acidic sites for hydrolysis, exhibits a superior catalytic performance for selective conversion of the microcrystalline cellulose to hexitols over the catalyst of mixing [Bmim]3PW12O40 and Ru/C. On the Ru/[Bmim]3PW12O40 catalyst, a sorbitol selectivity of 70.3% with a microcrystalline cellulose conversion of 63.7% was achieved in 24 h at 433 K and 5 MPa H2. The superior catalytic performance of Ru/[Bmim]3PW12O40 has been characterized using the hydrogenolysis of cellobiose as a probe reaction and was attributed to the Br?nsted acid sites generated from hydrogen spillover from the Ru sites to the O sites of the support. In situ generation of the Br?nsted acidic sites through hydrogen spillover has been confirmed by FT-IR characterization of pyridine adsorption. Furthermore, pH changes after treating the catalyst in H2 demonstrated that dissolution of the protons generated on the oxygen sites as a result of hydrogen spillover acidifies the liquid product. These Br?nsted acids work synergistically with the supported Ru and contribute to the enhanced hydrogenolysis activity.
- Xie, Xianna,Han, Jinyu,Wang, Hua,Zhu, Xinli,Liu, Xiao,Niu, Yufei,Song, Zhiqiang,Ge, Qingfeng
-
-
- Direct conversion of cellulose into acetol on bimetallic Ni-SnO x/Al2O3 catalysts
-
The direct conversion of cellulose into acetol was studied on SnO x-modified Ni/Al2O3 catalysts with different Sn/Ni atomic ratios in the range of 0-2.0. The selectivity to acetol strongly depended on the Sn/Ni ratios, which reached the highest value of 53.9% at the ratio of 0.5, compared at similar cellulose conversions (～20%). On Ni-SnOx/Al2O3 (Sn/Ni = 0.5), cellulose, glucose and fructose converted to acetol in high yields of approximately 35%, 53% and 73%, respectively, at 210 °C and 6 MPa H2. The effects of the Sn/Ni ratios on the acetol selectivity appear to be related to their effects on the hydrogenation activity of the Ni-SnOx/Al2O3 catalysts that decreased with increase of the Sn/Ni ratios, and to the relative rate between the hydrogenation of C6 sugar intermediates (e.g. glucose and fructose) and their degradation intermediates (e.g. glyceraldeyde and dihydroxyacetone) involved in the cellulose reaction on the Ni particles and the isomerization of glucose to fructose and their CC bond cleavage by retro-aldol condensation on the SnOx domains. Comparison of SnO x with CeOx, ZnOx and AlOx supported on Al2O3 with different basicity suggested that the larger concentration of stronger basic sites on SnOx facilitated the isomerizaiton of glucose to fructose and its subsequent CC bond cleavage. These results and their understanding provide guidance for improving the acetol production from cellulose by tuning the catalytic functions required for the involved reactions of hydrogenation on the metal surfaces, and isomerization and CC bond cleavage on the basic sites.
- Deng, Tianyin,Liu, Haichao
-
-
- Water-soluble polysaccharides from finger citron fruits (Citrus medica L. var. sarcodactylis)
-
Four water-soluble polysaccharides, FCp-1, FCp-2, FCp-3, and FCp-4 were obtained from finger citron fruits (Citrus medica L. var. sarcodactylis) by hot-water extraction and ethanol precipitation, followed by routine separation procedure. Based on the calibration curve, molecular weights of them were estimated to be 113.9, 32.6, 140.3, and 177.1 kDa respectively. The acid hydrolysis, methylation, IR, GC-MS, and NMR experiments were used for composition analysis. FCp-1 was a heteropolysaccharide composed of arabinose, galactose, glucose, rhamnose, and xylose, with a molar ratio of 3.0:7.0:4.1:1.0:1.5. FCp-2 and FCp-4 were →4)-α-d-GalpA(1→ linking galacturonan differ in molecular weights. FCp-3 was a →6)-α-d-Glcp(1→ linking glucan. According to the results of in vitro assays, FCp-3 showed significantly and moderately enhancing capacities toward the proliferation of splenocytes and thymocytes respectively. Thus, FCp-3 or analogs may have further use as immunomodulatory agents.
- He, Zhengchun,Liang, Fengjie,Zhang, Yuyang,Pan, Yuanjiang
-
p. 100 - 104
(2014/04/03)
-
- Conversion of sugars to ethylene glycol with nickel tungsten carbide in a fed-batch reactor: High productivity and reaction network elucidation
-
Bifunctional nickel tungsten carbide catalysis was used for the conversion of aqueous sugar solutions into short-chain polyols such as ethylene glycol. It is shown that very concentrated sugar solutions, viz. up to 0.2 kg L -1, can be converted without loss of ethylene glycol selectivity by gradually feeding the sugar solution. Detailed investigation of the reaction network shows that, under the applied reaction conditions, glucose is converted via a retro-aldol reaction into glycol aldehyde, which is further transformed into ethylene glycol by hydrogenation. The main byproducts are sorbitol, erythritol, glycerol and 1,2-propanediol. They are formed through a series of unwanted side reactions including hydrogenation, isomerisation, hydrogenolysis and dehydration. Hydrogenolysis of sorbitol is only a minor source of ethylene glycol. To assess the relevance of the fed-batch system in biomass conversions, both the influence of the catalyst composition and the reactor setup parameters like temperature, pressure and glucose addition rate were optimized, culminating in ethylene glycol yields up to 66% and separately, volume productivities of nearly 300 gEG L-1 h-1.
- Ooms, Roselinde,Dusselier, Michiel,Geboers, Jan A.,Op De Beeck, Beau,Verhaeven, Rick,Gobechiya, Elena,Martens, Johan A.,Redl, Andreas,Sels, Bert F.
-
p. 695 - 707
(2014/02/14)
-
- Aqueous-phase hydrogenation and hydrodeoxygenation of biomass-derived oxygenates with bimetallic catalysts
-
The reaction rate on a per site basis for aqueous-phase hydrogenation (APH) of propanal, xylose, and furfural was measured over various alumina-supported bimetallic catalysts (Pd-Ni, Pd-Co, Pd-Fe, Ru-Ni, Ru-Co, Ru-Fe, Pt-Ni, Pt-Co, and Pt-Fe) using a high-throughput reactor (HTR). The results in this paper demonstrate that the activity of bimetallic catalysts for hydrogenation of a carbonyl group can be 110 times higher than monometallic catalysts. The addition of Fe to a Pd catalyst increased the activity for hydrogenation of propanal, xylose, and furfural. The Pd1Fe3 catalyst had the highest reaction rate for APH of propanal among all catalysts tested in the HTR. The addition of Fe to the Pd catalyst increased the reaction rate for xylose hydrogenation by a factor of 51, compared to the monometallic Pd catalyst. However, no bimetallic catalyst tested in this study was more active than the monometallic Ru catalyst for hydrogenation of xylose. The Pd1Fe 3 catalyst had the highest reaction rate for APH of furfural, which was 9 times higher than the rate of the Pd catalyst. The Pd1Fe 3/Zr-P, a bimetallic bifunctional catalyst, was 14 times more active on a per site basis than a Pd/Zr-P catalyst for aqueous-phase hydrodeoxygenation (HDO) of sorbitol in a continuous flow reactor. The addition of Fe to the Pd catalyst increased the rate of C-C cleavage reactions and promoted the conversion of sorbitan and isosorbide in HDO of sorbitol. Pd1Fe 3/Zr-P also had a higher yield of gasoline-range products than the Pd/Zr-P catalyst.
- Lee, Jechan,Kim, Yong Tae,Huber, George W.
-
supporting information
p. 708 - 718
(2014/02/14)
-
- Crude Reaction Product Comprising Dianhydro Sugar Alcohol and Method for Preparing the Same
-
A crude reaction product includes: (A) about 90 to 100% by weight of a dianhydro sugar alcohol in a solid form and (B) about 0 to about 10% by weight of a reaction byproduct in a solid form. The reaction product is prepared by the steps of (a) preparing a monoanhydro sugar alcohol by reacting a sugar alcohol in the presence of a first cyclization catalyst and (b) preparing a dianhydro sugar alcohol by reacting the monoanhydro sugar alcohol in the presence of a second catalyst.
- -
-
Paragraph 0061; 0062; 0063; 0065
(2014/02/15)
-
- Xylanase XYN IV from Trichoderma reesei showing exo- and endo-xylanase activity
-
A minor xylanase, named XYN IV, was purified from the cellulolytic system of the fungus Trichoderma reesei Rut C30. The enzyme was discovered on the basis of its ability to attack aldotetraohexenuronic acid (HexA-2Xyl-4Xyl-4Xyl, HexA3Xyl3), releasing the reducing-end xylose residue. XYN IV exhibited catalytic properties incompatible with previously described endo-β-1,4-xylanases of this fungus, XYN I, XYN II and XYN III, and the xylan-hydrolyzing endo-β-1,4-glucanase EG I. XYN IV was able to degrade several different β-1,4-xylans, but was inactive on β-1,4-mannans and β-1,4-glucans. It showed both exo-and endo-xylanase activity. Rhodymenan, a linear soluble β-1,3-β-1,4-xylan, was as the best substrate. Linear xylooligosaccharides were attacked exclusively at the first glycosidic linkage from the reducing end. The gene xyn4, encoding XYN IV, was also isolated. It showed clear homology with xylanases classified in glycoside hydrolase family 30, which also includes glucanases and mannanases. The xyn4 gene was expressed slightly when grown on xylose and xylitol, clearly on arabinose, arabitol, sophorose, xylobiose, xylan and cellulose, but not on glucose or sorbitol, resembling induction of other xylanolytic enzymes from T. reesei. A recombinant enzyme prepared in a Pichia pastoris expression system exhibited identical catalytic properties to the enzyme isolated from the T. reesei culture medium. The physiological role of this unique enzyme remains unknown, but it may involve liberation of xylose from the reducing end of branched oligosaccharides that are resistant toward β-xylosidase and other types of endoxylanases. In terms of its catalytic properties, XYN IV differs from bacterial GH family 30 glucuronoxylanases that recognize 4-O-methyl-d-glucuronic acid (MeGlcA) substituents as substrate specificity determinants. 2012 The Authors Journal compilation
- Tenkanen, Maija,Vrsanska, Maria,Siika-Aho, Matti,Wong, Dominic W.,Puchart, Vladimir,Penttilae, Merja,Saloheimo, Markku,Biely, Peter
-
p. 285 - 301
(2013/03/28)
-
- Xylans are a valuable alternative resource: Production of d-xylose, d-lyxose and furfural under microwave irradiation
-
The influence of microwave irradiation on hydrolysis of xylan and simultaneous epimerization of the d-xylose to d-lyxose has been studied. An acidic solution of xylan was treated with catalytic amount of sodium molybdate and the composition of the reaction mixture was analyzed. Short reaction times of hydrolysis and subsequent epimerization reaction provided an equilibrium reaction mixture of d-xylose and d-lyxose (1.6:1) without significant formation of undesirable side products. Obtained pentoses can be reduced to the corresponding alditols (d-xylitol and d-lyxitol) in very good yields (88% and 85%) or can be further dehydrated to furfural (53%). Combined use of Mo(VI) catalyst and microwave irradiation allows better conversions and substantial reduction of reaction times (400-fold) compared to that obtained by conventional heating. Studied stereospecific transformation of xylan proceeds with high selectivity, short reaction times and very good yields that makes this approach attractive also for preparative purposes.
- Hricovíniová, Zuzana
-
p. 1416 - 1421
(2013/10/08)
-
- Ruthenium nanoparticles supported on zeolite y as an efficient catalyst for selective hydrogenation of xylose to xylitol
-
Zeolite Y (HYZ) supported ruthenium (Ru) nanoparticles catalysts are prepared by simple impregnation method and characterized by using different techniques such as TEM, TEM-EDX, SEM, XRD, FT-IR, surface area analysis and CO chemisorption. HYZ (different ratio of Si/Al) supported ruthenium catalysts are evaluated in hydrogenation of xylose to xylitol under green aqueous phase system. The reaction conditions are optimized by varying the stirring rate, ruthenium percent loading, xylose concentration, hydrogen partial pressure, reaction temperature and amount of catalyst to achieve the maximum conversion of xylose and selectivity to hydrogenated product xylitol. The activity of Ru/HYZ is also compared with that of conventional Ru/C catalyst at optimum reaction condition (120 C and 5.5 MPa pressure of H2 in 2 h). The reusability test of catalyst is carried out four times by recovering the catalyst from product solution.
- Mishra, Dinesh Kumar,Dabbawala, Aasif Asharaf,Hwang, Jin-Soo
-
-
