Conversion Of Monosaccharides Research Articles

Green biorefinery - the ultra-high hydrolysis rate and behavior of Populus tomentosa hemicellulose autohydrolysis under moderate subcritical water conditions.

A high monosaccharide conversion rate of hemicellulose in a green solvent and under moderate reaction conditions for industrialization is one of the most important keys in a lignocellulosic biorefinery. The behavior of Populus tomentosa hemicellulose polysaccharides, crystallinity and the furfural formation in the autohydrolysis process under moderate subcritical water conditions (160–180 °C, 0.618–1.002 MPa) were studied. The results have shown that the hemicellulose was converted to corresponding monosaccharides at an ultra-high hydrolysis rate. Factor analysis indicates that the temperature is the most important factor affecting hemicellulose autohydrolysis. When the autohydrolysis temperature increased from 160 to 180 °C for 2 h, the hydrolysis rate of xylose, rhamnose, galactose, mannose, and glucose from hemicellulose increased from 70% to 91%, 71% to 100%, 82% to 95%, 42% to 58%, and 34% to 37%, respectively. Arabinose was completely dissolved in 30 min. The xylose, rhamnose, galactose, and arabinose from hemicellulose could be almost completely removed under the conditions. The hemicellulose removal rate obtained herein exceeded the values reported for most acid, alkali, ionic liquid, or deep eutectic solvent treatments. It is notable that almost all glucose in hemicellulose was dissolved and the glucose in cellulose was partially hydrolyzed. An analysis of the sugar composition and the crystallinity change in the process at 180 °C demonstrate that hydrolysis reaction started to shift from amorphous regions to crystalline regions, due to the partial hydrolysis of crystalline cellulose after 90 min at 180 °C. Overall, these results show that the moderate subcritical water autohydrolysis of hemicellulose in Populus tomentosa may be a potential bio-refinery process.

Conversion of recalcitrant cellulose to alkyl levulinates and levulinic acid via oxidation pretreatment combined with alcoholysis over Al2(SO4)3

Conversion of cellulose to chemicals is an economic and environmental route for biomass utilization. In this work, efficient conversion of cellulose to alkyl levulinates and levulinic acid was realized by oxidation pretreatment combined with alcoholysis over Al2(SO4)3 catalyst. Proper pre-oxidation conditions including oxidation temperature and time are important. By pre-oxidation, part of hydroxymethyl groups on cellulose was converted to carboxyl groups which provide the Bronsted acid sites near the glycosidic bonds to improve the depolymerization of cellulose to monosaccharide. Al2(SO4)3·18H2O can play both Bronsted and Lewis acid roles in methanol and catalyze the conversion of monosaccharide to alkyl levulinates and levulinic acid. After pre-oxidation at optimized conditions, cellulose can be converted into methyl levulinate and levulinic acid over Al2(SO4)3 in methanol efficiently, and total yield of methyl levulinate and levulinic acid can reach 66.8% at 180 °C for 3 h. Furthermore, the simple and cheap Al2(SO4)3 catalyst is recyclable which is important for the practical application.

Kinetic variations in acid-catalyzed monosaccharide conversion

Kinetic models for the conversion of abundant carbohydrates have often remained controversial. Direct spectroscopic observations show that conversion of ketoses by Lewis acidic salts follows an exponential time course, while the corresponding conversion of aldoses follows a second order kinetics in various solvents and using various metal chloride catalysts. Brønsted acid catalyzed conversion of glucose and fructose displays two kinetic regimes due to the competition between the kinetically favored formation of anhydrosugars and the thermodynamically favored formation of furanics. Thus, slow kinetic phases occur towards the end of glucose conversion by Lewis and Brønsted acidic catalysis, albeit for different reasons.

Conversion of monosaccharides into levulinic acid/esters: impacts of metal sulfate addition and the reaction medium

AbstractBACKGROUNDInorganic salts could be used as catalysts for the effective conversion of sugars. In this study, the impacts of various metal sulfates (Na2SO4, K2SO4, MnSO4, CoSO4, NiSO4, ZnSO4, CuSO4, Fe2(SO4)3, La2(SO4)3 and Ce(SO4)2) on the conversion of glucose/fructose to levulinic acid in varied reaction media were evaluated.RESULTSThe sulfates strongly chelated with the sugars, preventing their dehydration reactions in the presence of sulfuric acid and leading to polymerization of the sugars. The sulfates themselves showed varied activity and selectivity for the conversion of the sugars to levulinic acid/esters or 5‐hydroxymethylfurfural (HMF), depending on the coordination with the reaction medium. K2SO4 or Na2SO4 could catalyze the production of HMF from glucose/fructose in water, while in DMSO the yield of HMF was substantially higher. In THF, nevertheless, almost no HMF was formed, while other sulfates such as NiSO4 in THF could effectively catalyze the conversion of fructose to HMF. In alcohols, Fe2(SO4)3 was the most effective sulfate for the conversion of the sugars to levulinic acid/esters, and the alcohols could effectively suppress the polymerization of the sugars.CONCLUSIONThe distinct catalytic performances of the sulfates in the varied reaction media originated from their different coordination or chelation with the sugars and the reaction medium. © 2019 Society of Chemical Industry

Thermo conversion of monosaccharides of biomass to oligosaccharides via mild conditions

Abstract A novel and green approach for production of oligosaccharides (Cello-oligosaccharides and Xylo-oligosaccharides) from monosaccharides (glucose and xylose) by thermoconversion in nitrogen atmosphere under mild conditions (300–700℃, 5–180 s) was investigated. The exploration of optimal conditions was used to evaluate the conversion process which showed that the conversion procedure was similarly under varied reaction temperatures, and it can be summarized into three stages, i.e. initial stage, formation of oligosaccharide stage and active reaction stage. The by-products in different stages were also analyzed and characterized in this work. The maximal oligosaccharides yield was about 40%, and the air was considered to be the appropriate quenching method for low temperature (

Across the Board: Keiichi Tomishige.

In this series of articles, the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. This entry features Prof. K. Tomishige, who highlights the importance of the chemical conversion of monosaccharides and the future necessity for the development of heterogeneous catalysts.

Bioconversion of xylose to xylonic acid via co-immobilized dehydrogenases for conjunct cofactor regeneration

Enzymatic cofactor-dependent conversion of monosaccharides can be used in the bioproduction of value-added compounds. In this study, we demonstrate co-immobilization of xylose dehydrogenase (XDH, EC 1.1.1.175) and alcohol dehydrogenase (ADH, EC 1.1.1.1) using magnetite-silica core-shell particles for simultaneous conversion of xylose into xylonic acid (XA) and in situ cofactor regeneration. The reaction conditions were optimized by factorial design, and were found to be: XDH:ADH ratio 2:1, temperature 25 °C, pH 7, and process duration 60 min. Under these conditions enzymatic production of xylonic acid exceeded 4.1 mM and was more than 25% higher than in the case of a free enzymes system. Moreover, the pH and temperature tolerance as well as the thermo- and storage stability of the co-immobilized enzymes were significantly enhanced. Co-immobilized XDH and ADH make it possible to obtain higher xylonic acid concentration over broad ranges of pH (6–8) and temperature (15–35 °C) as compared to free enzymes, and retained over 60% of their initial activity after 20 days of storage. In addition, the half-life of the co-immobilized system was 4.5 times longer, and the inactivation constant (kD = 0.0141 1/min) four times smaller, than those of the free biocatalysts (kD = 0.0046 1/min). Furthermore, after five reaction cycles, immobilized XDH and ADH retained over 65% of their initial properties, with a final biocatalytic productivity of 1.65 mM of xylonic acid per 1 U of co-immobilized XDH. The results demonstrate the advantages of the use of co-immobilized enzymes over a free enzyme system in terms of enhanced activity and stability.

One-pot sol–gel synthesis of a phosphated TiO2 catalyst for conversion of monosaccharide, disaccharides, and polysaccharides to 5-hydroxymethylfurfural

Catalytic conversion of biomass or biomass-derived carbohydrates into 5-hydroxymethylfurfural (HMF) is an important reaction for the synthesis of bio-based polymers, fuels, and other industrially useful products.

Effectively enhancing conversion of cellulose to HMF by combining in-situ carbonic acid from CO2 and metal oxides

Efficient valorization of cellulose is a sustainable route yet a challenging topic to solve the crisis of fossil resources. Although heterogeneous catalysts such as metal oxides have various advantages, the low surface contact area between metal oxides and cellulose is unfavourable for the hydrolysis of cellulose and thus restricts the application of metal oxides in direct conversion of cellulose to 5-hydroxymethylfurfural (HMF). This work presented the utilization of in-situ carbonic acid from CO2 as a green acid to enhance the conversion of cellulose to HMF in the presence of ZrO2 and TiO2. Combination of in-situ carbonic acid, ZrO2 and TiO2 exhibited a distinctive catalysis on the hydrolysis of cellulose and monosaccharide, isomerization of glucose and monosaccharide conversion in tetrahydrofuran (THF)/H2O/NaCl system. Especially, in-situ carbonic acid played a significant role in cellulose degradation and accelerated transforming insoluble polysaccharide into soluble oligosaccharide or monosaccharide, and thus promoted the cellulose conversion catalyzed by metal oxides. A high yield of HMF from cellulose (48.4%) was achieved by physically mixing commercial TiO2, ZrO2, and CO2. Due to the significant effects on cellulose degradation and HMF selectivity improvement, in-situ carbonic acid offers a green, low-cost and environmentally friendly co-catalyst for highly effective converting cellulose into HMF.

Catalysis performance comparison of a Brønsted acid H2SO4 and a Lewis acid Al2(SO4)3 in methyl levulinate production from biomass carbohydrates

An experimental investigation was conducted to understand the roles of the Brønsted acid H2SO4 and Lewis acid Al2(SO4)3 in methyl levulinate (ML) production from biomass carbohydrates, including glucose, fructose and cellulose. The product distributions with different catalysts revealed that the Lewis acid was responsible for the isomerization of methyl glucoside (MG), producing a significant amount of the subsequent product 5-methoxymethylfurfural (MMF), while the Brønsted acid facilitated the production of ML from MMF. Al2(SO4)3 was efficient for monosaccharide conversion but not for cellulose. Using ball-milled cellulose with Al2(SO4)3 resulted in a desired ML yield within a reasonable reaction time. The significant catalysis performances of two types of acids will guide the design of efficient catalytic processes for the selective conversion of biomass into levulinate esters.

Direct one-pot conversion of monosaccharides into high-yield 2,5-dimethylfuran over a multifunctional Pd/Zr-based metal–organic framework@sulfonated graphene oxide catalyst

A one-pot conversion of monosaccharides (fructose and glucose) into high-yield 2,5-dimethylfuran (2,5-DMF) is demonstrated over a multifunctional catalyst obtained by loading Pd on UiO-66@ sulfonated GO (Pd/UiO-66@SGO).

Selective direct conversion of C5 and C6 sugars to high added-value chemicals by a bifunctional, single catalytic body

The selective multi-step conversion of monosaccharides to anhydro-sugar alcohols was achieved in one-pot, one-stage by a bifunctional Ru catalyst.

Effect of Biological and Chemical Pre-treatment on the Hydrolysis of Corn Leaf

Hydrolysis of corn leaf utilizing two treatment sequences was carried out in this study. The first treatment was chemical and involved subjecting the corn leaf to an alkaline pre-treatment and then to a smooth acid hydrolysis. The second consisted of biological delignification using the strain Trametes sp. 44 H88, followed by enzymatic hydrolysis using the enzymatic extract produced by Trichoderma sp. H88. The ligninolytic extract produced by Trametes sp. 44 H88 was used to detoxify the hydrolyzate. The results indicate that biological pre-treatment with delignification is more favorable and improves the subsequent hydrolysis, regardless of whether the hydrolysis is chemical or biological. The chemical treatment sequence obtained 80% conversion of monosaccharides, while the biological treatment sequence resulted in a 87% conversion rate. Finally, the use of the ligninolytic extract for the dephenolization of the hydrolyzate reduced the presence of compounds of phenolic origin by 23%.

5-Hydroxymethylfurfural and levulinic acid derived from monosaccharides dehydration promoted by InCl3 in aqueous medium

Indium trichloride (InCl3) was used as catalyst for the conversion of monosaccharides into 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) in aqueous medium. 5-HMF yield of 60% (10min) and LA yield of 57% (60min) were achieved from glucose at 180°C with 2.5mol% of InCl3, and 5-HMF yield of 79% (15min) and LA yield of 45% (60min) were obtained from fructose under the same conditions. Moreover, the isomerization process between glucose and fructose was investigated through the comparative studies of glucose/fructose mixture with different ratios as substrates. It was found that InCl3 could not only catalyze the isomerization of glucose to fructose as well as the reverse direction, but also have the positive effects on the dehydration and conversion of monosaccharides. Based on this, a catalytic mechanism of dehydration of glucose and fructose promoted by InCl3 was proposed.

Efficient conversion of monosaccharides into 5-hydroxymethylfurfural and levulinic acid in InCl3–H2O medium

The conversion of fructose into 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) was investigated and catalyzed by indium trichloride (InCl3) in water. 79% 5-HMF yield (15min) and 45% LA yield (60min) were obtained at 180°C with 2.5mol% InCl3. Additionally, comparative studies of glucose/fructose mixture with different ratios as substrates were carried out to manifest the isomerization process between glucose and fructose during the conversion of monosaccharides into chemicals. It was shown that InCl3 was not only active in the isomerization of glucose to fructose and the reverse direction, but also demonstrated an excellent activity in the dehydration and conversion of monosaccharides. InCl3–H2O system presented a remarkable catalytic effect on the dehydration and conversion of monosaccharides.

The effect of hemicelluloses and lignin on acid hydrolysis of cellulose

In acid hydrolysis of plant biomass, polysaccharides are converted to monosaccharides, which is basic raw material for biorefinery for fermentation based process. These monosaccharides, however, are not stable in acidic reaction medium, and are converted to organic acids via furans. Impact of hemicelluloses and lignin on acid hydrolysis of cellulose was investigated to focus on monosaccharide production with different degrees of cellulose purity. Two-step concentrated sulphuric acid process was applied to biomass for monosaccharide conversion. Kinetics of cellulose hydrolysis was analysed using 1H NMR spectroscopy. Higher reaction temperature in secondary hydrolysis caused severe degradation of the monosaccharides. In pure and holocellulose, further reaction of glucose in acidic reaction medium produced formic acid and levulinic acid. However, lignocellulosic biomass generated much less formic acid and levulinic acid under the same reaction condition. Humin (or pseudo-lignin) was also formed by the condensation of lignin and furans from monosaccharides in acidic reaction condition. Thus, the fermentation inhibitors, furans and formic acid, were generated in low quantities by lignocellulosic biomass than by delignified biomass such as pure cellulose or holocellulose.

A water-tolerant C16H3PW11CrO39 catalyst for the efficient conversion of monosaccharides into 5-hydroxymethylfurfural in a micellar system

A water-tolerant cetyltrimethyl ammonium salt of transition metal (Cr(III)) substituted polyoxometalate C16H3PW11CrO39 (C16 = cetyltrimethyl ammonium) has been designed and used for the conversion of fructose and glucose into 5-hydroxymethylfurfural (HMF). The catalyst shows high conversion efficiency (90.3% and 84.2%, respectively) and high yields (40.6% and 35.2%, respectively) due to its dual acidity and hydrophobicity. The catalyst is stable during an aqueous-phase reaction and can be recycled via a simple separation process.

Kinetics of monosaccharide conversion in the presence of homogeneous Bronsted acids

For the utilization of biomass in the fuel and polymer industry, a wide variety of catalysts have been studied for their activity either on the dehydration reaction in particular or on the monosaccharide degradations in general. Yet, systematic data outlining the effects of acidic features is not available and a common framework for catalytic activity comparison is missing that is needed for rational catalyst design. The current work aimed to provide insight about the effect of the nature of the acid and initial acidity on degradation kinetics of C5 and C6 carbohydrates and thereby built a platform allowing activity comparison. Mineral and organic acids ranging in acidic strength, hydrochloric, sulfuric, phosphoric, maleic, and propane sulfonic acid, were tested for their activity in the degradation of xylose, fructose and glucose at two different pH values; 1.5 and 3.6. In the presence of weak homogeneous acids, glucose undergoes degradation with drastically different activation energies at pH of 1.5 than at pH 3.6. Such a difference does not occur in the presence of strong homogenous acids. On the other hand, xylose and fructose undergo degradation with similar activation energies of approximately 140kJ/mol regardless of the pH or nature of the homogeneous acid. A common framework that compiles the catalytic activities and outlines the differences potentially related to underlying mechanism changes provides the basis required for rational heterogeneous catalyst design.

Synthesis of the components of engine fuels on the basis of renewable raw materials: Trends and prospects

The basic methods for obtaining the components of engine fuels using the most commonly encountered type of raw materials, i.e., biomass polysaccharides, are discussed. The emphasis is placed upon two groups of methods of the conversion of polysaccharides: the heat treatment of the biomass with the subsequent processing of the resulting biopetrol with the conversion into the components of fuels using a hydroprocess and the selective conversion of monosaccharides into compounds that are subsequently used as components of fuels (along with hydrocarbons). Data on the synthesis of a new class of high-octane components of alcohol-containing fuels, i.e., ketals derived from polyols such as glycerol and pentoses, are given. It is shown that the effective catalysts of this process are some zeolites and ion-exchange resins.

Extremophile‐inspired strategies for enzymatic biomass saccharification

Domestic ethanol production in the USA relies on starch feedstocks using a first generation bioprocess. Enzymes that contribute to this industry remain of critical value in new and established markets as commodity additives and for in planta production. A transition to non‐food feedstocks is both desirable and essential to enable larger scale production. This objective would relieve dependence on foreign oil and strengthen the national economy. Feedstocks derived from corn stover, wheat straw, perennial grasses and timber require pretreatment to increase the accessibility of the cellulosic and hemicellulosic substrates to commodity enzymes for saccharification, which is followed by fermentation‐based conversion of monosaccharides to ethanol. Hot acid pretreatment is the industrial standard method used to achieve deconstruction of lignocellulosic biomass. Therefore, enzymes that tolerate both acid and heat may contribute toward the improvement of lignocellulosic biomass processing. These enzymes are produced naturally by extremely thermophilic microbes, sometimes called extremophiles. This review summarizes information on enzymes from selected (acido)thermophiles that mediate saccharification of α‐ and ß‐linked carbohydrates of relevance to biomass processing.