Hydrolysis Of Cellulose In Water Research Articles

Copper dispersed natural kaolinite as high-performance catalysts for the hydrolysis of cellulose in water

Copper dispersed natural kaolinite as high-performance catalysts for the hydrolysis of cellulose in water

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water.

Vermiculite is a natural mineral. In this study, vermiculite and acid-activated vermiculite was used as a solid acid catalyst for the hydrolysis of cellulose in water. The catalysts were characterized by XRD, FT-IR, and BET. The effects of time, temperature, mass ratio and water amount on the reaction were investigated in the batch reactor. The results showed that the highest total reducing sugars (TRS) yield of 40.1% could be obtained on the vermiculite activated by 35 (wt)% H2SO4 with the mass ratio of catalyst to cellulose of 0.18 and water to cellulose of 16 at 478 K for 3.5 h. The acid-activated vermiculite was a stable catalyst through calcination at 628 K and the yield of TRS decreased to 36.2% after three times reuse. The results showed that the crystal structure of vermiculite was destroyed and the surface -OH groups increased after the acid treatment. However, the synergistic effect of a strongly electrostatic polarization and Brönsted acid was responsible for the efficient conversion of cellulose. The mechanism of cellulose hydrolysis on the acid-activated vermiculite was suggested. This work provides a promising strategy to design an efficient solid catalyst for the cellulose hydrolysis, and expands the use of vermiculite in a new field.

Introducing hydroxyl groups as cellulose-binding sites into polymeric solid acids to improve their catalytic performance in hydrolyzing cellulose

Effective hydrolysis of cellulose to glucose is a crucial step to produce fuels and chemicals from lignocellulosic biomass. Solid acids are promising alternatives of cellulases and homogenous acids for hydrolyzing cellulose. In this study, porous polymeric solid acids bearing hydroxyl and sulfonic acid groups were fabricated for cellulose hydrolysis in water through the low-cost Friedel-Crafts “knitting” polymerization of hydroxyl-containing aromatic monomers followed by sulfonation. The synthesized bifunctional solid acids could effectively hydrolyze microcrystalline cellulose (Avicel) to glucose by as high as 93 % at 120 °C within 48 h and ball-milled Avicel by 98 % at 120 °C in 24 h. The evidence from this study indicated that the outstanding catalytic performance of the solid acids was attributed to the porous structure (large surface area) and the presence of the hydroxyl (cellulose-binding group) in the solid acids.

Enhanced Hydrolysis of Cellulose to Reducing Sugars on Kaolinte Clay Activated by Mineral Acid

Kaolinite, a natural, layered phyllosilicate, has been used as the solid catalyst for the hydrolysis of cellulose in our previous work. In the present study, kaolinite was activated by mineral acid and further evaluated for the hydrolysis of cellulose in water. The acid-activated kaolinite was characterized by XRF, XRD, FT-IR, BET and TG. The effects of reaction temperature, reaction time, mass ratio and water amount were investigated in the system. It was found that the highest total reducing sugars (TRS) yield of 50.2% was obtained on the kaolinite activated by 20% HNO3 with the mass ratio of catalyst to cellulose of 0.2 and water to cellulose of 14 at 205 ℃ for 3 h. Moreover, the catalyst was easily regenerated by calcination and the yield of TRS on the regenerated catalyst changed between 50.2% and 45.2% after four times reuse. The results showed that the acid activation could influence the crystallinity and improve the specific surface area, but the high TRS yield of the activated kaolinite should be ascribed to the increasing of the interlayer Al–OH groups and the formation of inner hydrogen bonds between the octahedral sheets and tetrahedral sheets. Finally, it was suggested that this was the effective way for improving the catalytic performance by increasing the interlayer Al–OH groups on the kaolinite catalyst.

Conversion of cellulose to high-yield glucose in water over sulfonated mesoporous carbon fibers with optimized acidity

Facilitated by superior mesoporous structure and rich functional groups, sulfonated mesoporous carbon fiber with optimized Brønsted and Lewis acidity delivers a high yield of glucose from cellulose hydrolysis in water.

Kaolinite: A natural and stable catalyst for depolymerization of cellulose to reducing sugars in water

Kaolinite, a natural, abundant, low cost, and eco-friendly material, has been widely used as filler, additives, adsorbent and coatings. In the study, kaolinite was evaluated for the performance of the hydrolysis of cellulose in water. The effects of mass ratio, reaction temperature, reaction time and water amount were investigated in a batch reactor. The fresh and regenerated catalysts were characterized by XRD, FT-IR and TG-DTG. The catalytic results showed that the highest TRS yield of 38.8% was obtained on the kaolinite at 200 °C with the mass ratio of catalyst to cellulose of 0.2 for 3 h. Moreover, kaolinite was a stable catalyst after regeneration and the yield of TRS decreased from 38.8% to 38.1% after five times reuse. Kaolinite contains abundant surface Al-OH groups, and the high TRS yield for kaolinite should be attributed to the H+ ions released from the surface OH groups. This work provides a promising strategy for efficient cellulose hydrolysis into fine chemicals by natural clay minerals.

Coupled Pretreatment with Liquid Nitrogen and Ball Milling for Enhanced Cellulose Hydrolysis in Water.

A key problem in the conversion of cellulose into chemicals and fuels is the low product yield from cellulose due to its robust structure. In this work, for the first time, cellulose was pretreated with coupling of liquid nitrogen and ball milling (LN–BM) for cellulose hydrolysis. After the LN–BM treatment, the glucose yield from cellulose by HCl in water increased by almost 2 times and yield of formic acid catalyzed by H2SO4–NaVO3 was more than 3-fold that obtained from untreated cellulose. The yields were also much higher than that from the individually ball-milled cellulose. The structure variation of cellulose indicated that reduction of both crystallinity index and molecular weight contributed to improving the conversion efficiency, but the former was the dominant factor. The combination of liquid nitrogen and ball milling developed in this work is an effective and environment-friendly approach for cellulose pretreatment.

Eco-Friendly Ca-Montmorillonite Grafted by Non-Acidic Ionic Liquid Used as A Solid Acid Catalyst in Cellulose Hydrolysis to Reducing Sugars.

An effective and friendly method was developed for the production of reducing sugars (RS) from the hydrolysis of cellulose over the solid catalyst of Ca-montmorillonite (Mt) grafted by non-acidic ionic liquid (Mt-IL) in water. The effect of mass ratio, water dosage, reaction temperature, and time were investigated in a batch reactor. Raw Mt showed only a 7.9% total reducing sugars (TRS) yield for the catalytic hydrolysis of cellulose in water. As the Mt was grafted by -SO3H and IL, the TRS yield greatly increased under the same reaction conditions. The highest TRS yield of 35.7% was obtained on the catalyst of Mt grafted by non-acidic IL at 200 °C with the mass ratio of catalyst to cellulose of 0.2 for 120 min. The high TRS yield for Mt-IL should be attributed to the synergistic effect of the dissolution of cellulose by IL and the exposed metal ions on the layer with water. Although the yield of TRS on Mt-IL decreased gradually with recycling runs, the decrease after the first run was not very serious compared to the fresh catalyst. This work provides a promising strategy for efficient cellulose hydrolysis into fine chemicals by Mt with non-acidic IL.

Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO42−-TiO2 in water–ethanol solvent

Abstract An efficient catalyst SO42−-TiO2 (ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 °C (ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 °C for 30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Bronsted acid sites ratio for ST-450 induced by bidentate ligands between SO42− and TiO2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of 0.29 cm3·g−1 and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 °C exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO42− and TiO2 are considered as active acid sites for cellulose hydrolysis in water–ethanol solvents.

Acid–base synergistic catalysis of biochar sulfonic acid bearing polyamide for microwave-assisted hydrolysis of cellulose in water

The development of a highly efficient heterogeneous catalysis process for the hydrolysis of cellulose to reducing sugars (RSs) and especially 5-hydroxymethylfurfural (HMF) in water is highly anticipated for large-scale use of cellulosic biomass in the future. Herein, a bamboo-derived biochar sulfonic acid bearing polyamide (BCSA-PA) designed by us was found to show much higher catalytic activity, better repeatability and especially HMF yield for microwave-assisted such hydrolysis compared to the PA-free BCSA, achieving 25.60% RSs and 23.10% HMF yields with 4.71 turnover number (TON) under optimal conditions. Also, its TON value (2.58) for the conversion of cellulose into HMF was much higher than those obtained from it-catalyzed transformation of glucose (TON, 1.44) and especially fructose (TON, 0.79). The BCSA-PA showing an excellent catalysis performance in cellulose hydrolysis is likely due to the following two reasons: (1) the BCSA and especially BCSA-PA, as supported by glucose and cellobiose adsorption experiments, have a stronger affinity to β-1,4-glycosidic bonds of cellulose than two monosaccharides, thereby leading to the highly-efficient hydrolysis of cellulose on the SO3H groups. (2) The acid–base synergistic catalysis between the SO3H and PA groups of BCSA-PA may be responsible for its higher HMF selectivity and excellent repeatability in water medium. The current work highlights new opportunities for the direct production of 5-HMF from glucose and especially cellulose.

Efficient hydrolysis of cellulose to glucose in water by agricultural residue-derived solid acid catalyst

A carbonaceous solid acid catalyst bearing weakly acidic carboxylic and phenolic functional groups was facilely prepared by the pyrolysis of cow dung followed by KOH activation. The prepared carbonaceous material showed low activity for the catalytic hydrolysis of raw cellulose in water (3.6% glucose yield). However, after the cellulose was pretreated by mixing with the carbonaceous catalyst in a ball mill, cellulose hydrolysis afforded a high glucose yield of 59.3% in water at 200 °C, and the glucose yield increased to 74% under the same reaction conditions in 0.015 wt% HCl aqueous solution. The increases were attributed to the decrease in degree of crystallinity of the cellulose, as well as good contact between the catalytic domain in the catalyst and the β-1,4-glycosidic bonds in the cellulose molecules by the mix-milling pretreatment. This work provides a promising strategy for efficient cellulose hydrolysis in water by a weakly acidic solid catalyst prepared from the agricultural residues.

Bifunctional Porous Polymers Bearing Boronic and Sulfonic Acids for Hydrolysis of Cellulose

A facile strategy is reported in this study to synthesize bifunctional porous polymers bearing boronic and sulfonic acids as a new type of cellulase-mimetic solid acids for cellulose hydrolysis in water. The boronic acid and sulfonic acid groups of the solid acids mimicked the cellulose-binding domains and the cellulose-hydrolytic domains of cellulase, respectively. As expected, the cellulase-mimetic solid acids were able to hydrolyze microcrystalline cellulose (Avicel) to glucose effectively because of the synergic effect between the boronic and sulfonic groups. For example, the solid acid synthesized from naphthalene-1-boronic acid at 120 °C was able to hydrolyze Avicel to glucose by 42.7% at 24 h and 94.6% at 48 h, respectively. If the Avicel was ball-milled for 2 h, it could be hydrolyzed by 94.9% within 24 h at 120 °C.

Mesoporous H-ZSM-5 as an efficient catalyst for conversions of cellulose and cellobiose into methyl glucosides in methanol

The alcoholysis of cellobiose, which is a dimer of glucose and a model molecule of cellulose, has been studied in methanol medium in the presence of various solid acids. Zeolite H-ZSM-5 was found to be highly efficient for the conversion of cellobiose into methyl glucosides (including methyl-α-glucoside and methyl-β-glucoside) in methanol. The Brønsted acidity plays a key role in the catalytic alcoholysis of cellobiose. H-ZSM-5 with a lower Si/Al ratio (20) possessed higher density of acidic sites afforded a higher methyl glucoside yield (53%) for the conversion of cellobiose at 423K. The introduction of mesoporosity into the zeolite significantly enhanced its catalytic performance. Methyl glucosides with a yield of 73% were achieved from cellobiose over a mesoporous H-ZSM-5 (H-meso-ZSM-5-0.5M) sample with an average mesopore size of 6.1nm. The mesoporous ZSM-5 could also catalyze the direct transformation of cellulose in methanol, providing methyl glucosides with yields of 51% at 463K. Our comparative studies revealed that the alcoholysis of cellulose in methanol proceeded more efficiently than the hydrolysis of cellulose in water under similar reaction conditions.

1-(1-Propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed hydrolysis of cellulose in water: Effect of metal ion co-catalysts

The effect of eight metal ions, Cr3+, Mn2+, Fe3+, Co2+ Ni2+, Cu2+, Zn2+ and La3+ on 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed hydrolysis of cellulose in water was studied at 140–170°C. Mn2+, Fe3+, and Co2+ as co-catalysts produced significant enhancements in total reducing sugar (TRS) yields, with Mn2+ showing the highest activity. Mn2+ as co-catalyst produced 91.8, and 91.9% TRS yields, whereas samples without Mn2+ gave 28.0 and 28.7% yields at 160 and 170°C respectively. The observed activation energies for cellulose hydrolysis without a co-catalyst and with Mn2+ co-catalyst are 78.1±1.4 and 32.8±4.9kJ·mol−1 respectively.

Solvents effects on the mechanism of cellulose hydrolysis: A QM/MM study.

This article reports a combined quantum mechanics/molecular mechanics (QM/MM) investigation on the acid hydrolysis of cellulose in water using two different models, cellobiose and a 40-unit cellulose chain. The explicitly treated solvent molecules strongly influence the conformations, intramolecular hydrogen bonds, and exoanomeric effects in these models. As these features are largely responsible for the barrier to cellulose hydrolysis, the present QM/MM results for the pathways and reaction intermediates in water are expected to be more realistic than those from a former density functional theory (DFT) study with implicit solvent (CPCM). However, in a qualitative sense, there is reasonable agreement between the DFT/CPCM and QM/MM predictions for the reaction mechanism. Differences arise mainly from specific solute-solvent hydrogen bonds that are only captured by QM/MM and not by DFT/CPCM.

Synthesis of a silica-immobilized Brönsted acidic ionic liquid catalyst and hydrolysis of cellulose in water under mild conditions

A silica immobilized imidazolium-type acidic ionic liquid catalyst was shown to be a better catalyst than n-propylsulfonic acid silica (PrSO3H-SiO2) and sulfonic acid silica (SO3H-SiO2) for the hydrolysis of untreated Sigmacell Cellulose (DP~450) in water. For example, new catalyst produced the highest TRS yield of 48.1% after 3h at 190°C, whereas cellulose samples heated with PrSO3H-SiO2 and SO3H-SiO2 catalysts produced only 19.9% and 13.2% TRS yields, respectively, under identical conditions. The new catalyst could be recycled up to four cycles with a small loss in catalytic activity.

Sulfonic Acid Group Functionalized Ionic Liquid Catalyzed Hydrolysis of Cellulose in Water: Structure Activity Relationships

Catalytic activities of eight sulfonic acid group functionalized ionic liquids in water were compared for the hydrolysis of Sigmacell cellulose (DP ~ 450) in the 150-180°C temperature range by measuring total reducing sugar (TRS) and glucose produced. The catalytic activity of acidic ionic liquids with different cation types decreases in the order imidazolium > pyridinium > triethanol ammonium cation. Among the sulfonic acid group functionalized imidazolium ionic liquids, the catalysts which contain a single imidazolium ion and a flexible linker between sulfonic acid group and the imidazolium ionic liquid core structure are the most active catalysts.

Synthesis of an Immobilized Brönsted Acidic Ionic Liquid Catalyst and Hydrolysis of Cellulose in Water Under Mild Conditions

Synthesis of an Immobilized Brönsted Acidic Ionic Liquid Catalyst and Hydrolysis of Cellulose in Water Under Mild Conditions

Aryl sulfonic acid catalyzed hydrolysis of cellulose in water

Catalytic activities of eight alkyl/aryl sulfonic acids in water were compared with sulfuric acid of the same acid strength (0.0321mol H+ ion/L) for hydrolysis of Sigmacell cellulose (DP∼450) in the 140–190°C temperature range by measuring total reducing sugar (TRS), and glucose produced. Cellulose samples hydrolyzed at 160°C for 3h, in aqueous p-toluenesulfonic acid, 2-naphthalenesulfonic acid, and 4-biphenylsulfonic acid mediums produced TRS yields of 28.0, 25.4, and 30.3% respectively, when compared to 21.7% TRS produced in aqueous sulfuric acid medium. The first order rate constants at 160°C in different acid mediums correlated with octanol/water distribution coefficient logD of these acids, except in the case of highly hydrophobic 4-dodceylbenzenesulfonic acid. In the series of sulfonic acids studied, 4-biphenylsulfonic acid appears to be the best cellulose hydrolysis catalyst.

Effect of acid catalyst on structural transformation and hydrolysis of cellulose in hydrothermal conditions

The effect of H2SO4 on the crystalline-to-amorphous transformation and hydrolysis of cellulose in water at high temperatures and high pressures was revealed for the first time by using in situ high-resolution optical microscopy.