The search for and exploitation of efficient catalytic systems for selective conversion of furfural into various high value-added chemicals remains a huge challenge for green synthesis in the chemical industry. Here, novel Pt nanoparticles supported on bamboo shoot-derived porous heteroatom doped carbon materials were designed as highly active catalysts for controlled hydrogenation of furfural in aqueous media. The porous heteroatom doped carbon supported Pt catalysts were endowed with a large surface area with a hierarchical porous structure, a high content of nitrogen and oxygen functionalities, a high dispersion of the Pt nanoparticles, good water dispersibility and reaction stability. Benefiting from these features, the novel Pt catalysts displayed a high activity and controlled tunable selectivity for furfural hydrogenation to produce furfuryl alcohol and cyclopentanone in water. The product selectivity could be easily modulated by controlling the carbonization temperature of the porous heteroatom doped carbon support and the reaction conditions (temperature and H2 pressure). Under mild conditions (100 °C, 1 MPa H2), furfuryl alcohol was obtained in water with complete conversion of the furfural and an impressive furfuryl alcohol selectivity of >99% in the presence of Pt/NC-BS-500. A higher reaction temperature, in water, favored rearrangement of the furfural (FFA) with Pt/NC-BS-800 as the catalyst, which resulted in a high cyclopentanone yield of >76% at 150 °C and 3 MPa H2. The surface properties and pore structure of the heteroatom doped carbon support, adjusted using the carbonization temperature, might determine the interactions between the Pt nanoparticles, carbon support and catalytic reactants in water, which in turn could have led to a good selectivity control. The effect of different reaction temperatures and reaction times on the product selectivity was also explored. Combined with exploration of the distribution of the reaction products, a reaction mechanism for furfural reduction has been proposed.

Enzyme immobilization is believed to provide an excellent base for increasing environmental tolerance of enzyme and considerable period of time. In this work, a kind of nonporous silica nanoparticles functionalized with amino group was synthesized to immobilize proline-specific endoprotease (PSEP). PSEP is known to specifically cleave peptides (or esters) at the carboxyl side of proline, thus can prevent the formation of haze and prolong the shelf life of beer. After immobilization, the environmental tolerance (temperature and pH, respectively) was obviously improved, and the immobilized enzyme can retain above 90 % of its original activity after 6 uses. Moreover, the immobilized enzyme can effectively prevent the formation of chill-haze using fresh beer fermentation liquid.

Demands for high strength integrated materials have substantially increased across various kinds of industries. Inspired by the relationship of excellent integration of mechanical properties and hierarchical nano/microscale structure of the natural nacre, a simple and facile method to fabricate high strength integrated artificial nacre based on sodium carboxymethylcellulose (CMC) and borate cross-linked graphene oxide (GO) sheets has been developed. The tensile strength and toughness of cellulose-based hybrid material reached 480.5 ± 13.1 MPa and 11.8 ± 0.4 MJm–3 by a facile in situ reduction and cross-linking reaction between CMC and GO (0.7%), which are 3.55 and 6.55 times that of natural nacre. This hybrid film exhibits better thermal stability and flame retardancy. More interestingly, the hybrid material showed good water stability compared to that in the original water-soluble CMC. This type of hybrid has great potential applications in aerospace, artificial muscle, and tissue engineering.Keywords: artificial nacre; bio-based; graphene oxide; high strength and toughness; in situ reduction and cross-linking;

•Modification of carbon nanotubes supported Ru catalysts were prepared, nature of acidic or basic sites of functional groups played crucial role.•With nitrogen doping to carbon nanotubes, the activity of Ru was improved in sorbitol hydrogenolysis.•All the alkali hydroxide promoters significantly enhanced the sorbitol conversion, while NaOH promoter gave the highest conversion and glycol yields.Different functional groups (i.e. NH2, COOH, OH and nitrogen-doping) modified CNTs (denoted as AMCN, CMCN, HMCN and NMCN, respectively) supported ruthenium catalysts (Ru/AMCN, Ru/CMCN, Ru/HMCN and Ru/NMCN) were prepared by incipient wetness impregnation method. They were fully characterized by XRD, TG, Raman, XPS, TPD and TEM to elucidate the relationship between the physical property and their catalytic performance. TEM results shown that Ru particles were well dispersed on the surface for all the samples with the size of 1.48–1.99 nm. The effects of functional groups of carbon nanotubes (CNTs), nitrogen doping and base additive types on activity and selectivity of ethylene glycol (EG) and propylene glycol (1,2-PD) were investigated. In addition, the activity and final products distribution were much influenced by the properties of functional groups on CNTs and the type of metal cation of the base promoters, which probably participated in the reaction for accelerating a retro-aldol reaction for CC cleavage. Among the catalysts, Ru supported on AMCN exhibited the best catalytic activities and glycols selectivities than on MCN, CMCN, HMCN and NMCN.Functional groups of CNTs acted as anchoring site for Ru and obstructed the sintering of ruthenium clusters which therefore maintained high dispersion on these catalysts. The nature of these groups played crucial role on the activity of sorbitol hydrogenolysis. The presence of a solid base promoter or nitrogen doping facilitates dehydration of polyols and subsequent deoxygenation while restraining the methanation reaction.

Sustainable production of liquid transportation fuels and chemicals remains essential both commercially and scientifically. Isobutanol has gained great attention as an improved “drop-in” biofuel and important commodity chemical with broad applications. Ethanol could be upgraded with methanol in water for the production of isobutanol through cross condensation. High isobutanol selectivity is obtained (>90%) due to precise control on the reactivity of methanol and ethanol feedstock over Ir catalysts immobilized on N functionalized carbon materials. Only under a narrow range of preparation conditions could the catalysts distinguish the reactivity of methanol and ethanol nicely. The experimental results evidenced that the properties of Ir, especially the particle size and oxidation state, were particularly important for the desired activity. Control experiments also indicated that the effect of Ir catalysts on the intermediate aldol C–C formation step, rather than the dehydrogenation step, was critical in determining the product selectivity. Furthermore, the Ir catalysts could tolerate some typical biogenic impurities, which enables catalytic upgrading of bio-ethanol broth after centrifugation and decolourization. All these results indicate the promising application of the developed Ir catalysts in producing biofuels as well as useful chemicals from ethanol upgrading.

•The MMT-CS/QDs solution and films possess strong fluorescence intensity.•The MMT-CS/QDs solution and films present good storage stability.•The fluorescence wavelength was controllable by refluxing with different time.A method was presented for fabricating the fluorescent nanocomposites containing CdTe quantum dots (QDs) and montmorillonite (MMT)-chitosan (CS). MMT-CS/CdTe QDs nanocomposites were prepared via a simple, versatile and robust approach combination of covalent and electrostatic assembly methods (Scheme 1). The negatively charged MMT was initially modified with positively charged CS through electrostatic assembly, followed by incorporation of CdTe-QDs into the MMT-CS nanosheets by covalent connections between the amino groups of CS and the carboxylic acid groups of thioglycollic acid (TGA). The X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and the FTIR were used to prove the QDs have intercalated into the MMT-CS matrix. The fluorescence emission spectra showed that the MMT-CS/CdTe QDs nanocomposites had the best fluorescence intensity compared with the bare CdTe QDs and CS-QDs.

•A CS-AgNWs film is prepared by using efficacious Solution Casting Method.•CS-AgNWs film showed more tensile strength and less resistivity than CS-AgNPs film.•Prepared biofilm with good conductivity also exhibited antimicrobial activity.•Current research present multifunctional CS-AgNWs film.A bio-based hybrid film containing chitosan (CS) and silver nanowires (AgNWs) has been prepared by a simple casting technique. X-ray diffraction (XRD), Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV–visible spectroscopy were employed to characterize the structure of bio-based film. The bio-based hybrid film showed unique performance compared with bare chitosan film. The incorporated nano-silver could improve the strength properly. The results revealed that AgNWs in CS film, improved its tensile strength more than 62% and Young modulus 55% compared with pure chitosan film. On the other hand tensile strength was increased 36.7% with AgNPs. Importantly, the film also exhibited conductivity and antibacterial properties, which may expand its future application.

•Four types of nanocellulose were isolated from corncob residues.•The structures and properties of prepared nanocellulose were comparatively studied.•FA hydrolysis yielded longer cellulose nanocrystals with higher crystallinity.•Pulp refining produced the largest nanofibers with highly networked structure.In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production.

Succinic acid is an important biomass-derived C4 building block and is ready to be converted into various value-added chemicals. Here we report that tunable selectivity for the formation of 1,4-butanediol, γ-butyrolactone and tetrahydrofuran from aqueous succinic acid hydrogenation could be achieved on FeOx-promoted Pd/C catalysts. Fe was found to be an efficient promoter for the succinic acid hydrogenation, which not only improved the activity of the catalysts but also tuned the product distribution. Succinic acid could be transformed into 1,4-butanediol with a yield of over 70% in the presence of the Pd–5FeOx/C catalyst under the relatively mild conditions of 200 °C and 5 MPa H2. The reaction pathway was also proposed according to the reaction and characterization results.

In this work, novel hybrid microbeads composed of chemically reduced graphene oxide (CRGO) and alginate were fabricated, which could encapsulate enzymes by a simple non-covalent adsorption–entrapment method. Compared with alginate gel beads, the intervention of CRGO in the alginate gel enhanced its mechanical strength, effectively prevented the leakage of enzyme, and greatly enhanced the stability and environmental tolerance. Compared with free enzymes or those on a single carrier, the enzyme encapsulated in these hybrid microbeads can retain its optimum activity within a broad range (temperature 45–60 °C, pH 4–6). Additionally, the microbeads can be easily recycled by simple filtration and filled into a column to achieve a continuous fixed-bed enzyme catalytic reaction.

•CNCs could be isolated by formic acid (FA) hydrolysis.•FA could be recovered and reused in the production of CNCs.•CNCs produced by FA could be modified by TEMPO-mediated oxidation.•The modified CNCs had higher surface charge and better redispersibility in water.•The modified CNCs could be more effective when used as rheology modifier.Cellulose nanocrystals (CNCs) as a renewable and biodegradable nanomaterial have wide application value. In this work, CNCs were extracted from bleached chemical pulp using two stages of isolation (i.e. formic acid (FA) hydrolysis and 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) mediated oxidation) under mild conditions. In the first stage, FA was used to remove hemicellulose, swell cellulose fibers, and release CNCs. The FA could be readily recovered and reused. In the second stage, the CNCs isolated by FA were further modified by TEMPO-mediated oxidation to increase the surface charge of CNCs. It was found that the modified CNCs with more ordered crystal structure and higher surface charge had better redispersibility and higher viscosity in aqueous phase. Therefore, the modified CNCs could be more effective when used as rheology modifier in the fields of water based coating, paint, food etc.

Bio-alcohols (e.g. ethanol, butanol) are primarily obtained as diluted aqueous solutions from biomass fermentation, and thus the subsequent isolation is a very costly process. So the direct transformation of bio-alcohols in water will have great advantages. This study describes the development of catalysts used for the self-condensation of bio-alcohols in water (that mimic the primary fermentation solutions). Efficient iridium catalysts have been developed rationally from homogeneous to heterogeneous, and the immobilized catalysts could be reused without any loss of activity, which is very important for the development of practical processes. The expected self-condensation could be realized with 80–90% selectivity in water and air. Such a protocol might be used for producing butanol from ethanol solution directly, which is an improved higher-alcohol biofuel. Other useful chemicals, such as 2-ethylhexanol, could also be obtained from renewable resources through this condensation reaction.

Here we report a simple and efficient approach to fabricate a new biocatalytic system by co-immobilizing multi-enzyme on chemically reduced graphene oxide (CRGO) via non-covalent bonds. The obtained artificial biocatalyst was characterized by UV/Vis, FTIR, AFM, TEM and SEM. Compared with native and graphene oxide (GO) bounded enzymes, it was found that the glucose oxidase (GOD) or glucoamylase (GA) immobilized on CRGO exhibited significantly higher enzymatic activity, due to the positive effect of the CRGO carrier. This multi-enzyme microsystem was employed as a biocatalyst to accomplish the starch-to-gluconic acid reaction in one pot, and the yield of gluconic acid could reach 82% within 2 hours. It was also proved that the stability of the multi-enzyme biocatalyst immobilized on CRGO was dramatically enhanced compared with the GO microsystem. About 85% of the activity of the artificial biocatalyst could be preserved after four cycles. These results demonstrated the feasibility of the novel strategy to construct bio-microsystems with multi-enzyme on 2D CRGO via non-covalent bonds to accomplish some complex conversions.

The conversion of biomass-derived 5-hydroxymethylfurfural (HMF) was examined over Ni–Co–Al mixed oxide catalysts derived from corresponding hydrotalcite-like compounds (HTlcs). 1,2,6-Hexanetriol (1,2,6-HT) was obtained in 64.5% yield under mild reaction conditions. The catalysts were characterized by X-ray powder diffraction (XRD), CO2 temperature-programmed desorption (CO2–TPD), N2 physical adsorption, and H2 temperature-programmed reduction (H2–TPR), and the reaction product distribution was correlated with the catalyst composition and reaction conditions. The reaction pathway was proposed based on the results. In all cases, the conversion of HMF proceeds according to a pathway that begins with the aldehyde group being hydrogenated to form 2,5-dihydroxymethylfuran (2,5-DHF). This product then undergoes a ring-opening reaction to form 1,2,6-HT. A synergetic effect between Ni and Co was observed, which significantly promoted catalytic activity and selectivity.Keywords: 1,2,6-Hexanetriol; 5-Hydroxymethylfurfural; CoO; Furan derivatives; Mixed metal oxide catalyst; NiO

The conversion of renewable, non-edible and resource-abundant lignocellulose to fuels, chemicals and materials has received significant attention as it holds the possibility of using carbon neutral technologies to combat global changes. Considering the relatively high oxygen content in cellulose, it is more desirable to be transformed into oxygenated chemicals rather than hydrocarbon fuels in view of atom efficiency. Among the oxygen-rich chemicals from biomass, polyols, such as ethylene glycol and propylene glycol, are widely used in polymer synthesis, food industry and manufacturing of pharmaceuticals. Hydrolysis, coupled with hydrogenation and hydrogenolysis serves as an effective approach to transform biomass to polyols. This review summarizes the recent advances in biomass upgrading reactions for the production of polyols with a special emphasis on the formation of glycols.

In this study, the alkaline twin-screw extrusion pretreated corn stover was subjected to enzymatic hydrolysis after washing. The impact of solid loading and enzyme dose on enzymatic hydrolysis was investigated. It was found that 68.2 g/L of total fermentable sugar could be obtained after enzymatic hydrolysis with the solid loading of 10 %, while the highest sugar recovery of 91.07 % was achieved when the solid loading was 2 % with the cellulase dose of 24 FPU/g substrate. Subsequently, the hydrolyzate was fermented by Clostridium acetobutylicum ATCC 824. The acetone–butanol–ethanol (ABE) production of the hydrolyzate was compared with the glucose, xylose and simulated hydrolyzate medium which have the same reducing sugar concentration. It was shown that 7.1 g/L butanol and 11.2 g/L ABE could be produced after 72 h fermentation for the hydrolyzate obtained from enzymatic hydrolysis with 6 % solid loading. This is comparable to the glucose and simulated hydrozate medium, and the overall ABE yield could reach 0.112 g/g raw corn stover.

Selective hydrogenolysis of biomass-derived tetrahydrofurfuryl alcohol (THFA) to produce 1,5-pentanediol (1,5-PeD) is accomplished by a binary catalyst consisting of MoO3 and supported Rh nanoparticles; a 1,5-PeD selectivity up to 80% is achieved in the present work. Moreover, a very interesting phase-transfer behavior for MoO3 during the reaction is observed with the assistance of different characterization techniques. In this process, MoO3 dissolves partially in the liquid phase under the reaction conditions and is transformed into the soluble hydrogen molybdenum oxide bronzes (HxMoO3) in the presence of H2, which are recognized as the genuinely active sites for the C–O bond breaking of THFA. Density functional theory (DFT) calculations were then carried out to simulate the plausible mechanisms and highlight the role of Mo in the ring-opening process of THFA in more detail. We propose that the formation of 1,5-PeD takes place in a two consecutive reactions. THFA first undergoes acid-catalyzed ring-opening process to form the key intermediate 5-hydroxypentanal with the homogeneous catalysis of dissolved HxMoO3. The intermediate is then quickly hydrogenated into 1,5-PeD under the heterogeneous catalysis of Rh. The concerted “hydrogen-transfer–ring-opening” mechanism plausibly explains the high reaction selectivity toward 1,5-PeD in the hydrogenolysis of THFA and is verified by the reactivity trends of related substrates.

Mesoporous silica–cellulose hybrid composites were prepared by surface sol–gel coating process on nature cellulose substance. The template CTAB (hexadecyl trimethyl ammonium Bromide) in the silica film can be removed by extraction to obtain high specific surface area (80.7 m2 g–1), which is 2 orders of magnitude higher than that of raw cellulose. In the following, the enzyme-mimetic catalyst and chromogenic agent were introduced onto the hybrid system. Just as the peroxidase, the resultant hybrid material exhibits extraordinary sensitivity for the H2O2 and shows an immediate and obvious color change. The detection limit is about 1 μmol L–1 by the naked eye.Keywords: enzyme-mimetic catalyst; H2O2 detection; hybrid nanostructures; mesoporous silica;

Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational design of better catalysts for propanediol synthesis, which is one of the major challenges for glycerol application in energy. In this work, extensive calculations based on periodic density functional theory were carried out to study thermodynamics of glycerol hydrogenolysis over binary model catalysts, including Cu/ZrO2 and Cu/MgO, with the focus to elucidate the competitive reaction pathways to produce the 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO). Our results suggest that the reaction starts with glycerol dehydration on the metal oxide, followed by sequential hydrogenation over metal centers. Based on our explorations on the stabilities of adsorbed reactants, dehydrated intermediates and hydrogenated species along the reaction channels, the DFT calculations show that the 1,2-PDO formation will dominate in comparison to the 1,3-PDO from thermodynamic viewpoint. This is consistent with our experiments where the Cu catalysts seem to give the 1,2-PDO as a main product. The calculations and experiments also indicate that the Cu/MgO exhibits superior activities than Cu/ZrO2 for the hydrogenolysis of glycerol molecules.

A green and effective approach for comprehensive component utilization of lignocellulosic biomass has been described, based on the hydrolysis of lignocellulosic biomass with a carbonaceous solid acid (CSA) derived from the hydrolyzed biomass residues under microwave irradiation. The as-synthesized CSA was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX), which proved that the acid groups (–SO3H, –COOH) were successfully introduced onto the surface of CSA. Significantly, the CSA showed excellent catalytic hydrolysis performance for the lignocellulosic biomass under microwave irradiation, especially for the conversion of hemicellulose of the biomass. Microwave irradiation could greatly enhance the catalytic performance in our system. Various reaction parameters, such as temperature, reaction time, the amount of CSA and the ratio of solid to liquid, were evaluated. At mild temperatures (383–413 K), the cellulose and hemicellulose in the corncobs could be decomposed into corresponding sugars. The maximum glucose yield, xylose yield and arabinose yield could reach 34.6, 77.3 and 100%, respectively. The CSA can be recycled and reused. This approach may offer a promising strategy for the hydrolysis of lignocellulosic biomass in the future.

Nickel supported on a variety of supports was evaluated in the batchwise hydrogenolysis of high-crystalline cellulose under hydrothermal conditions. The supports examined included Al2O3, kieselguhr, TiO2, SiO2, activated carbon (AC), ZnO, ZrO2 and MgO. All tested catalysts can effectively convert cellulose while the choice of supports plays a critical role in the product distribution and selectivity. The Ni catalysts favour the formation of industrially attractive 1,2-alkanediols such as 1,2-propanediol, ethylene glycol, 1,2-butanediol and 1,2-hexanediol. It was found that the bifunctional ZnO-supported Ni catalysts displayed superior activities and the best result was obtained on 20% Ni/ZnO which exhibited complete conversion of cellulose with up to 70.4% total glycol yields. The mechanism of the reaction involved was tentatively proposed by identifying the products formed.

The well-defined sulfonated block copolymer poly(acrylic acid)-block-poly(styrene sulfonic acid) (PAA-b-PSSH) and the random copolymer poly(acrylic acid)-random-poly(styrene sulfonic acid) (PAA-r-PSSH) were prepared by direct thermolysis of the precursor copolymers poly(tert-butyl acrylate)-block-poly(neopentyl styrenesulfonate) (PtBA-b-PNSS) and poly(tert-butyl acrylate)-random-poly(neopentyl styrenesulfonate) (PtBA-r-PNSS), which were synthesized by living radical polymerization (MWD < 1.10) catalyzed with CuBr. GPC, EA, 1H NMR and FT-IR spectra were employed to characterize the structure of the synthesized acid polymers. The catalytic performance of the acid polymers was evaluated for the hydrolysis of starch and cellulose in aqueous solution under microwave irradiation. With the same effective acid concentration, the random copolymer PAA-r-PSSH gave the highest glucose yield among the prepared catalysts. It is believed that the good results were caused by the synergic effect of the SO3H and COOH groups in the polymer chain. In addition, microwave irradiation led to better glucose yields in the hydrolysis of polysaccharides than the conventional heating method with acid polymers as catalysts.

Magnetic Fe3O4–cellulose–chitosan hybrid gel microspheres were prepared by sol–gel transition technology using ionic liquids as solvent for cellulose and chitosan dissolution and regeneration. The synthesized microspheres were characterized by XRD, FTIR, SEM, and vibrating sample magnetometer (VSM). The XRD and FTIR results showed that chitosan and cellulose had been successfully coated onto the surface of Fe3O4 after the preparation. SEM presented that the synthesized microspheres were regular sphere with a mean diameter of about 10 μm. Furthermore, it was found that glucose oxidase (GOx) could be successfully immobilized on the hybrid gel microspheres via glutaraldehyde technique. The immobilized enzyme presented higher thermostability, wider range of pH optima and improved storage stability in comparison with free GOx. The glucose conversion could reach 91.5% within 4 h and retained 84.2% of the initial activity after 15 cycles of use. These results demonstrate their potential applications in the field of biocatalysis.

Highly homogeneous TiO2@phenolic resol hybrid nanocomposites are fabricated by a solvothermal method. In such nanostructures, the TiO2 particles are tightly grafted on the surface of nano mesoporous phenolic resols to form uniform heterostructures. Significantly, a charge transfer complex was formed at the interface of the TiO2 and the nano mesoporous phenolic resols, which led to visible-light absorption over the full range. The nano hybrid material exhibited excellent performance for the photocatalytic degradation of dyes and produced photocurrent signals under visible-light. The investigation of the mechanism indicated that the O2˙− was the main active species during the photochemical process. The hybrid nanocomposites also showed considerably high stability in the photocatalysis. It is expected that this approach can provide a new strategy for the design of some bio-inspired catalysts for sustainable technology.

Magnetic hybrid hydrogels with a novel polymeric coating consisting of chitosan and cellulose were prepared. By coating cellulose and chitosan, we combined the renewability and biocompatibility of cellulose and chitosan as well as the magnetic properties of Fe3O4 to create a hybrid system to adsorb heavy metals.

Concentrated H3PW12O40 (HPW) was first employed to decompose cellulose under microwave irradiation at low temperatures. 75.6% yield of glucose was obtained at 90 °C under microwave irradiation for 3 h, which was considerably high under such mild conditions using phosphotungstic acid as a catalyst. With the same effective acid concentration, HPW gave the highest cellulose conversion and glucose yield among the Brønsted acid catalysts, indicating that the strong Brønsted acid played an important role during cellulose hydrolysis. In the hydrolysis of cellulose with HPW as catalysts, microwave irradiation led to higher glucose yields than the conventional heating method. The recovery and reusability of HPW were investigated by extraction with diethyl ether from the reaction solution. At the same time, the performance of the concentrated HPW for real lignocellulosic biomass (corncob, corn stover and bagasse) hydrolysis was also investigated.

Mesoporous SBA-15 materials functionalized with propylsulfonic acid groups (SBA-15-SO3H) were synthesized through a conventional one-pot route. It was used as a catalyst for the selective synthesis of 5-hydroxymethylfurfural (HMF) from the dehydration of fructose using BmimCl as solvent. Reaction time, temperature and fructose concentration were investigated during the HMF synthesis procedure. The catalyst SBA-15-SO3H exhibits high fructose conversion (near 100%) and HMF selectivity (about 81%) with good stability in the HMF synthesis. It was a suitable catalyst to produce HMF from renewable carbohydrates in potential industrial process.Graphical abstractPropylsulfonic acid functionalized SBA-15 catalysts were used to prepare 5-hydroxymethylfurfural (HMF) using BmimCl as solvent. This made the simple SBA-15-SO3H-BmimCl system a promising choice for fructose dehydration.Highlights► SBA-15-SO3H was an environmentally benign solid catalyst for the dehydration of fructose. ► The catalyst was tolerant to high concentration feedstock and can be reused. ► High HMF selectivity of 81.0% with above 97% fructose conversion was obtained. ► The separation of HMF was successfully achieved in a THF/BmimCl biphasic system.

Conversion of fructose and glucose into 5-hydroxymethylfurfural (HMF) was investigated in various imidazolium ionic liquids, including 1-butyl-3-methylimidazolium chloride (BmimCl), 1-hexyl-3-methylimidazolium chloride (HmimCl), 1-octyl-3-methylimidazolium chloride (OmimCl), 1-benzyl-3-methylimidazolium chloride (BemimCl), 1-Butyl-2,3-dimethylimidazolium chloride (BdmimCl), and 1-butyl-3-methylimidazolium p-toluenesulfonate (BmimPS). The acidic C-2 hydrogen of imidazolium cations was shown to play a major role in the dehydration of fructose in the absence of a catalyst, such as sulfuric acid or CrCl3. Both the alkyl groups of imidazolium cations and the type of anions affected the reactivity of the carbohydrates. Although, except BmimCl and BemimCl, other four ionic liquids could only achieve not more than 25% HMF yields without an additional catalyst, 60–80% HMF yields were achieved in HmimCl, BdmimCl, and BmimPS in the presence of sulfuric acid or CrCl3 in sufficient quantities.Graphical abstractHighlights► The acidic C-2 hydrogen of imidazolium cation catalyzes the dehydration of fructose. ► The cations and anions of imidazolium ionic liquids affect the reactivity of hexoses. ► Higher temperatures and catalyst loadings decrease the ionic liquid’s side effects.

Conversion of fructose into furan derivatives 5-hydroxymethylfurfural (HMF) and 5-methoxymethylfurfural (MMF) is performed in tetrahydrofuran (THF) and methanol–organic solvent systems, catalysed by an acidic resin Amberlyst-15. The melted fructose can be converted into HMF on the surface of the solid resin catalyst in the presence of THF as an extracting phase, which is a good solvent for HMF and other by-products. The solid resin catalyst can be reused eleven times without losing its catalytic ability, with an average HMF yield of approximately 50%. Upon the addition of methanol, the generated HMF can further react with methanol to form MMF, and the total yield of HMF and MMF could be promoted to 65%. GC–MS analysis confirms the formation of a small amount of methyl levulinate in methanolorganic solvent system.

Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that –SO3H, –COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.

Water extract of steam-exploded corn stalk (SECS) was detoxified and used as feed for acetone–butanol–ethanol (ABE) fermentation using Clostridium beijerinckii. Utilization of water extract improved the total ABE yield (g ABE/g dry SECS). Separated fermentation showed higher fermentability (0.078 g ABE/g dry SECS) over typical fermentation (0.058 g ABE/g dry SECS). Furthermore, the final ABE yields (g ABE/g utilized sugar) from water extract neutralized by Ca(OH)2, NaOH, and Na2SO3 were 0.16, 0.1 and 0.07, respectively, suggesting that Ca(OH)2 had the best detoxification effect.

Novel complex nanospheres with core/shell structure for selective adsorption of Hg2+ have been prepared by a simple one-pot method. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed the nanospheres had perpendicularly thiol-functionalized mesoporous SiO2 hybrid shell and Fe3O4@SiO2 core (Fe3O4@nSiO2@mSiO2–SH). XRD patterns of as-synthesized nanospheres confirmed the observation of the SEM and TEM. The size of the nanospheres is about 100 nm. Based on the analysis of N2 sorption–desorption isotherm, the surface area and pore volume of the adsorbent are 861 m2/g and 0.48 cm3/g, respectively. The saturation magnetization value for Fe3O4@nSiO2@mSiO2–SH is as high as 6.87 emu g−1. The nanospheres showed more accessible active sites and high dispersibility in water, exhibited excellent performance for selective Hg2+ adsorption, had a stable structure, and could be recycled easily with magnet.

Magnetic hybrid hydrogels with a novel polymeric coating consisting of chitosan and cellulose were prepared. By coating cellulose and chitosan, we combined the renewability and biocompatibility of cellulose and chitosan as well as the magnetic properties of Fe3O4 to create a hybrid system to adsorb heavy metals.

Succinic acid is an important biomass-derived C4 building block and is ready to be converted into various value-added chemicals. Here we report that tunable selectivity for the formation of 1,4-butanediol, γ-butyrolactone and tetrahydrofuran from aqueous succinic acid hydrogenation could be achieved on FeOx-promoted Pd/C catalysts. Fe was found to be an efficient promoter for the succinic acid hydrogenation, which not only improved the activity of the catalysts but also tuned the product distribution. Succinic acid could be transformed into 1,4-butanediol with a yield of over 70% in the presence of the Pd–5FeOx/C catalyst under the relatively mild conditions of 200 °C and 5 MPa H2. The reaction pathway was also proposed according to the reaction and characterization results.

In this work, novel hybrid microbeads composed of chemically reduced graphene oxide (CRGO) and alginate were fabricated, which could encapsulate enzymes by a simple non-covalent adsorption–entrapment method. Compared with alginate gel beads, the intervention of CRGO in the alginate gel enhanced its mechanical strength, effectively prevented the leakage of enzyme, and greatly enhanced the stability and environmental tolerance. Compared with free enzymes or those on a single carrier, the enzyme encapsulated in these hybrid microbeads can retain its optimum activity within a broad range (temperature 45–60 °C, pH 4–6). Additionally, the microbeads can be easily recycled by simple filtration and filled into a column to achieve a continuous fixed-bed enzyme catalytic reaction.

The well-defined sulfonated block copolymer poly(acrylic acid)-block-poly(styrene sulfonic acid) (PAA-b-PSSH) and the random copolymer poly(acrylic acid)-random-poly(styrene sulfonic acid) (PAA-r-PSSH) were prepared by direct thermolysis of the precursor copolymers poly(tert-butyl acrylate)-block-poly(neopentyl styrenesulfonate) (PtBA-b-PNSS) and poly(tert-butyl acrylate)-random-poly(neopentyl styrenesulfonate) (PtBA-r-PNSS), which were synthesized by living radical polymerization (MWD < 1.10) catalyzed with CuBr. GPC, EA, 1H NMR and FT-IR spectra were employed to characterize the structure of the synthesized acid polymers. The catalytic performance of the acid polymers was evaluated for the hydrolysis of starch and cellulose in aqueous solution under microwave irradiation. With the same effective acid concentration, the random copolymer PAA-r-PSSH gave the highest glucose yield among the prepared catalysts. It is believed that the good results were caused by the synergic effect of the SO3H and COOH groups in the polymer chain. In addition, microwave irradiation led to better glucose yields in the hydrolysis of polysaccharides than the conventional heating method with acid polymers as catalysts.

Magnetic Fe3O4–cellulose–chitosan hybrid gel microspheres were prepared by sol–gel transition technology using ionic liquids as solvent for cellulose and chitosan dissolution and regeneration. The synthesized microspheres were characterized by XRD, FTIR, SEM, and vibrating sample magnetometer (VSM). The XRD and FTIR results showed that chitosan and cellulose had been successfully coated onto the surface of Fe3O4 after the preparation. SEM presented that the synthesized microspheres were regular sphere with a mean diameter of about 10 μm. Furthermore, it was found that glucose oxidase (GOx) could be successfully immobilized on the hybrid gel microspheres via glutaraldehyde technique. The immobilized enzyme presented higher thermostability, wider range of pH optima and improved storage stability in comparison with free GOx. The glucose conversion could reach 91.5% within 4 h and retained 84.2% of the initial activity after 15 cycles of use. These results demonstrate their potential applications in the field of biocatalysis.

Highly homogeneous TiO2@phenolic resol hybrid nanocomposites are fabricated by a solvothermal method. In such nanostructures, the TiO2 particles are tightly grafted on the surface of nano mesoporous phenolic resols to form uniform heterostructures. Significantly, a charge transfer complex was formed at the interface of the TiO2 and the nano mesoporous phenolic resols, which led to visible-light absorption over the full range. The nano hybrid material exhibited excellent performance for the photocatalytic degradation of dyes and produced photocurrent signals under visible-light. The investigation of the mechanism indicated that the O2˙− was the main active species during the photochemical process. The hybrid nanocomposites also showed considerably high stability in the photocatalysis. It is expected that this approach can provide a new strategy for the design of some bio-inspired catalysts for sustainable technology.