Tunable and selective hydrogenation of furfural to furfuryl alcohol and cyclopentanone over Pt supported on biomass-derived porous heteroatom doped carbon.

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.

Immobilization of proline-specific endoprotease on nonporous silica nanoparticles functionalized with amino group.

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.

Acetone-butanol-ethanol production from corn stover pretreated by alkaline twin-screw extrusion pretreatment.

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.

Improved efficiency of separate hexose and pentose fermentation from steam-exploded corn stalk for butanol production using Clostridium beijerinckii.

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 Na(2)SO(3) were 0.16, 0.1 and 0.07, respectively, suggesting that Ca(OH)(2) had the best detoxification effect.

High-strength and morphology-controlled aerogel based on carboxymethyl cellulose and graphene oxide.

Composite aerogels with excellent mechanical properties were prepared by using carboxymethyl cellulose (CMC) as raw materials, 2D graphene oxide (GO) nanosheets as reinforcement, boric acid (BA) as cross-linker. By controlling the heat transfer rate, composite aerogels with isotropy and anisotropy structure were prepared, the mechanical and heat insulation properties were studied. The isotropy composite aerogel had compression strength of 110 kPa at 60% compression, which was 5 times of the axial and 14 times of the radial of anisotropy structure composite aerogels, and thermal conductivity was also lower than those of two directions of anisotropy composite aerogel. Besides, the mechanical properties of isotropy composite aerogels increased with the increase of GO content. When GO content was up to 5 wt%, the compressive strength and Young's modulus of composite aerogels reached 349 kPa and 1029 kPa, which were 1.6 and 4.5 times that of CMC aerogels, respectively.

Low-temperature PROX (preferential oxidation) on novel CeO(2)-supported Cu-cluster catalysts under fuel-cell operating conditions.

Cu(1+)-clusters on a CeO(2) support, which were prepared by hydrothermal synthesis using cetyltrimethylammonium bromide (CTAB), were found to be highly active and selective for preferential oxidation (PROX) of CO in excess H(2) with H(2)O and CO(2) under practical fuel-cell operating conditions.

A novel hierarchical porous nitrogen-doped carbon derived from bamboo shoot for high performance supercapacitor.

Porous N-doped carbons hold good prospects for application in supercapacitor due to their low-cost, large surface area, good surface wettability, high electrical conductivity as well as extra pseudocapacitance. However, most synthetic methods required the tedious and multiple-step process with the assistance of hard/soft templates or the massive use of chemical reagents, and exogenous nitrogen sources, which made them difficult to realize industrial production and application. Here, we described a novel hierarchical porous N-doped carbons fabricated by a facile and sustainable approach via hydrothermal treatment and subsequent carbonization process by using renewable bamboo shoots as the starting material without any templates, additional chemical activation and nitrogen source. The obtained bamboo shoot-derived carbons possessed a large BET surface area (up to 972 m2 g-1), hierarchically interconnected porous framework, rich and uniform nitrogen incorporation (3.0 at%). Benefiting from these unique features, the novel carbon-based electrode materials displayed a high capacitance of 412 F g-1 in KOH electrolyte and long cycling life stability. Thus, an advanced electrode material for high-performance supercapacitor was successfully assembled by a simple and scalable synthesis route with abundant renewable resources freely available in nature.

Antimicrobial Bamboo Materials Functionalized with ZnO and Graphene Oxide Nanocomposites.

Bamboo materials with improved antibacterial performance based on ZnO and graphene oxide (GO) were fabricated by vacuum impregnation and hydrothermal strategies. The Zn2+ ions and GO nanosheets were firstly infiltrated into the bamboo structure, followed by dehydration and crystallization upon hydrothermal treatment, leading to the formation of ZnO/GO nanocomposites anchored in the bulk bamboo. The bamboo composites were characterized by several techniques including scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and X-ray diffraction (XRD), which confirmed the existence of GO and ZnO in the composites. Antibacterial performances of bamboo samples were evaluated by the bacteriostatic circle method. The introduction of ZnO/GO nanocomposites into bamboo yielded ZnO/GO/bamboo materials which exhibited significant antibacterial activity against Escherichia coli (E. coli, Gram-negative) and Bacillus subtilis (B. subtilis, Gram-positive) bacteria and high thermal stability. The antimicrobial bamboo would be expected to be a promising material for the application in the furniture, decoration, and construction industry.

Iridium Clusters Encapsulated in Carbon Nanospheres as Nanocatalysts for Methylation of (Bio)Alcohols.

C-H methylation is an attractive chemical transformation for C-C bonds construction in organic chemistry, yet efficient methylation of readily available (bio)alcohols in water using methanol as sustainable C1 feedstock is limited. Herein, iridium nanocatalysts encapsulated in yolk-shell-structured mesoporous carbon nanospheres (Ir@YSMCNs) were synthesized for this transformation. Monodispersed Ir clusters (ca. 1.0 nm) were encapsulated in situ and spatially isolated within YSMCNs by a silica-assisted sol-gel emulsion strategy. A selection of (bio)alcohols (19 examples) was selectively methylated in aqueous phase with good-to-high yields over the developed Ir@YSMCNs. The improved catalytic efficiencies in terms of activity and selectivity together with the good stability and recyclability were contributable to the ultrasmall Ir clusters with oxidation chemical state as a consequence of the confinement effect of YSMCNs with interconnected nanostructures.

Reduced Graphene Oxide/Alumina, A Good Accelerant for Cellulose-Based Artificial Nacre with Excellent Mechanical, Barrier, and Conductive Properties.

In this article, a simple strategy was employed to fabricate bioinspired hybrid composite with carboxymethyl cellulose (CMC), graphene oxide, and reduced graphene oxide/alumina (rGO/Al) by a facile solution casting method. The tensile strength and toughness of rGO/Al-CMC-GO can reach 586.6 ± 12 MPa, 12.1 ± 0.44 MJm-3, respectively, due to the interface strengthening of alumina, which is 1.43 and 12 times higher than steel and about 4.3 and 6.7 times that of nature nacre. The artificial nacre hybrid composite is conductive due to the introduction of rGO/Al on the surface. Interestingly this structure can also be coated on the surface of cotton thread to give the thread good mechanical performance and conductivity. Additionally, the artificial nacre has better fire shielding and gas barrier properties. The oxygen permeability (OP) for 1% rGO/Al-CMC decreased from 0.0265 to 0.003 mLµm m-2 day-1 kpa-1, the water vapor permeability (WVP) decreased from 0.363 to 0.205 gmmm-2 day-1 kpa-1 when the concentration increased from 1% rGO/Al to 6% rGO/Al. It is believed this work provided a simple and feasible strategy to fabricate ultrastrong and ultratough graphene-based artificial nacre multifunctional materials.

Bio-Based Artificial Nacre with Excellent Mechanical and Barrier Properties Realized by a Facile In Situ Reduction and Cross-Linking Reaction.

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.

Hemicellulose isolation, characterization, and the production of xylo-oligosaccharides from the wastewater of a viscose fiber mill.

Viscose fiber mills generate a lot of wastewater enriched with hemicelluloses. The structure of the hemicellulose in the wastewater was characterized and the hemicellulose was isolated to produce xylo-oligosaccharides (XOS). It was confirmed that the hemicellulose was mainly 4-O-methylglucuronoxylan with a small amount of glucomannan and xyloglucan. The 4-O-methylglucuronoxylan was completely de-acetylated and linear with a few 4-O-methyl glucuronic acid attached. After purified by the acid precipitation and washing, the hemicellulose was pretreated by dilute acid, and then subjected to xylanase hydrolysis. After the dilute H2SO4 pretreatment at pH 2.6 and 150°C for 30min and the followed xylanase hydrolysis (65IU/g xylan), the total XOS yield was improved from 0.215 to 0.578g/g xylan. The percentage of XOS in the final sugar product was 68.9%. These results demonstrated the potential economical and environmental benefits of the process to utilize the byproducts from viscose fiber mills.

Highly selective hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on g-C3N4 nanosheets catalysts in water.

Graphitic carbon nitride nanosheets were investigated for developing effective Pt catalyst supports for selective hydrogenation of furfural to furfuryl alcohol in water. The nanosheets with an average thickness of about 3 nm were synthesized by a simple and green method through thermal oxidation etching of bulk g-C3N4 in air. Combined with the unique feature of nitrogen richness and locally conjugated structure, the g-C3N4 nanosheets with a high surface area of 142 m(2) g(-1) were demonstrated to be an excellent supports for loading small-size Pt nanoparticles. Superior furfural hydrogenation activity in water with complete conversion of furfural and high selectivity of furfuryl alcohol (>99%) was observed for g-C3N4 nanosheets supported Pt catalysts. The large specific surface area, uniform dispersion of Pt nanoparticles and the stronger furfural adsorption ability of nanosheets contributed to the considerable catalytic performance. The reusability tests showed that the novel Pt catalyst could maintain high activity and stability in the furfural hydrogenation reaction.

Highly Selective Upgrading of Biomass-Derived Alcohol Mixtures for Jet/Diesel-Fuel Components.

In light of the increasing concern about the energy and environmental problems caused by the combustion of petroleum-based fuels (e.g., jet and diesel fuels), the development of new procedures for their sustainable production from renewable biomass-derived platform compounds has attracted tremendous attention recently. Long-chain ketones/alcohols are promising fuel components owing to the fuel properties that closely resemble those of traditional fuels. The focus of this report is the production of long-chain ketones/alcohols by direct upgrading of biomass-derived short-chain alcohol mixtures (e.g., isopropanol-butanol-ethanol mixtures) in pure water. An efficient Pd catalyst system was developed for these highly selective transformations. Long-chain ketones/alcohols (C8 -C19 ), which can be used as precursors for renewable jet/diesel fuel, were obtained in good-to-high selectivity (>90 %) by using the developed Pd catalyst.

Tough and multi-responsive hydrogel based on the hemicellulose from the spent liquor of viscose process.

The hemicellulose isolated from the spent liquor of a viscose process was successfully utilized to prepare hydrogels by the graft copolymerization of acrylic acid (AA) with hemicellulose. The hemicellulose and prepared hydrogel were characterized by Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), and solid-state nuclear magnetic resonance ((13)C NMR). Under the optimum preparation conditions, the highest compressive strength and strain at break of the resultant hydrogel were 105.1±12.9kPa and 34.8%, respectively. Furthermore, the maximum equilibrium swelling degree of prepared hydrogel was 192. Also, the hydrogel could rapidly respond to pH, salt and ethanol. Taken together, the prepared hydrogels had great mechanical and multi-responsive properties. Thus, the prepared hydrogels had a great potential application in drug release, water treatment and cell immobilization. In addition, the utilization of alkaline extracted hemicellulose from the viscose fiber factory has huge market potential and economic benefits.

Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

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.

A novel method for fabricating hybrid biobased nanocomposites film with stable fluorescence containing CdTe quantum dots and montmorillonite-chitosan nanosheets.

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.