Conversion of d-glucose into 5-hydroxymethylfurfural (HMF) using zeolite in [Bmim]Cl or tetrabutylammonium chloride (TBAC)/CrCl2

The formation of hydroxymethylfurfural (HMF) from glucose was studied. It was found that the CrCl₂-catalyzed conversion in the ionic liquid, butylmethylimidazolium chloride ([Bmim]Cl) leads to negligible quantities of 3-deoxyglucosone confirming that fructose is the main intermediate. It was found that the environmentally unfriendly chromium salt could be replaced with zeolite (H-ZSM-5) leading to a 45% yield of HMF. It was also found that the solvent [Bmim]Cl could be replaced with non-toxic tetrabutylammonium chloride (TBAC) giving a 56% yield of HMF.     

Inorganics distribution in bio oils and char produced by biomass fast pyrolysis: The key role of aerosols

Fast pyrolysis of biomass is a promising process for the preparation of bio-oil dedicated to energy production. Inorganic species originally present in biomass are known to induce problems such as bio-oil instability or deposits and fouling. However the mechanisms of inorganic species release during biomass pyrolysis into the raw bio-oils still remain unclear. The present work focuses on the determination of inorganic distribution in the products from wheat straw and beech wood fast pyrolysis performed in a fluidized bed. More specifically, the bio-oils are fractionated by using a series of condensers. The results show that more than 60 wt.% of the inorganic content of the overall bio-oil is contained in the aerosols. Several possible interpretations for this observation are discussed. It is likely that the inorganics are transported within the aerosols droplets and solid particles which are recovered in the bio-oils, either by mechano-chemical processes, or by entrainment of submicron intermediate liquid compound formed in the first steps of biomass fast pyrolysis.     

Au负载SBA-15分子筛上葡萄糖氧化反应

探讨了金与铝改性的SBA-15分子筛催化剂(Au-Al/SBA-15)上活性中心与葡萄糖氧化制葡萄酸反应性能的关系. 通过固体核磁共振波谱(ssNMR)、 X射线光电子能谱(XPS)、 紫外-可见光谱(UV-Vis)和透射电子显微镜(TEM)等手段对不同Au及Al含量的Au-Al/SBA-15催化剂进行了结构表征. 发现Al 改性能够在SBA-15载体上产生四配位Al物种, Au主要以单质的形式存在; SBA-15上的四配位Al物种具有稳定Au颗粒大小的作用. 通过对比发现, 催化剂上的Au和骨架四配位Al物种间的相互协作促进了对葡萄糖氧化的活性, 而非骨架Al物种会导致副反应的发生, 降低葡萄糖酸产物的选择性. 通过固体¹³C NMR揭示了反应体系中的NaOH能够将强吸附的产物葡萄糖酸分子从催化剂表面解离, 保持活性位不被覆盖进而促进反应持续进行.     

Evaluation of Acacia nilotica as a non conventional low cost biosorbent for the elimination of Pb(II) and Cd(II) ions from aqueous solutions

In the present study a biomass derived from the leaves of Acacia nilotica was used as an adsorbent material for the removal of cadmium and lead from aqueous solution. The effect of various operating variables, viz., adsorbent dosage, contact time, pH and temperature on the removal of cadmium and lead has been studied. Maximum adsorption of cadmium and lead arises at a concentration of 2 g/50 ml and 3 g/50 ml and at a pH value of 5 and 4, respectively. The sorption data favored the pseudo-second-order kinetic model. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were applied to describe the biosorption isotherm of the metal ions by A. nilotica biomass. Based on regression coefficient, the equilibrium data found were fitted well to the Langmuir equilibrium model than other models. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated, respectively revealed the spontaneous, endothermic and feasible nature of adsorption process. The activation energy of the biosorption (Ea) was estimated as 9.34 kJ mol⁻¹ for Pb and 3.47 kJ mol⁻¹ for Cd from Arrhenius plot at different temperatures.     

纤维素直接催化转化制乙二醇及其他化学品:从基础研究发现到潜在工业应用(英)

纤维素直接催化转化制乙二醇是一条极具吸引力的生物质转化途径,有助于减轻化石能源资源的消耗。综述了从该反应途径的发现到获得高效、高稳定性催化剂的快速发展过程。基于对钨基催化剂的大量研究结果,本文讨论了反应机制,明确了反应路径、催化剂状态、钨物种及加氢催化活性中心各自在串联反应中的作用。围绕该反应过程的工业化应用需要,讨论了有关原生木质纤维素生物质催化转化以及高效反应过程的发展策略。在此基础上,将纤维素催化转化制乙二醇过程与生物质发酵制丙酮-丁醇-乙醇的生物炼制路线进行整合,构建出一个理想的反应过程潜在应用范例。最后,对纤维素催化转化制乙二醇反应过程进行了总结和前景展望.     

A biomass carbon material with microtubule bundling and natural O-doping derived from goldenberry calyx and its electrochemical performance in supercapacitor

A promising biomass carbon material,manufactured by the carbonation of Physalis peruviana L.calyx at 700℃,is presented in this wo rk.Morphology characterization shows that the carbon material possesses long microtubule bundling and above 30%natural O-atom component on the surface.After KOH chemical etching,the materials maintain the oxygen content but exhibit more micropores and higher specific surface area up to 1732.6 m^2/g.Using as an electrode material for supercapacitor,the active carbon material exhibits high specific capacitance up to 339.7 F/g at 0.5 A/g in 3 mol/L KOH aqueous solution through three-electrode system.The active carbon material also exhibits excellent cycling stability(97%retention)by 10,000 cycles at 10 A/g.The outstanding electrochemical performances are attributing to the unique long microtubule bundling with much more pores and the abundant Oelement on the surface.This biomass carbon material with excellent electrochemical properties could be a useful material for multiple applications.     

Versatile carbon supported mono and bimetallic nanocomposites: synthesis,characterization and their potential application for furfural reduction

Biomass conversion has been developed by testing various metal based carbon catalysts. Most of the reported catalysts either use very expensive metals or support that provides lower selectivity. In this context, we fabricated new carbon based nanocomposites and studied their catalytic application for furfural reduction – a promising biomass derived molecule. The mono (Cu, Co and Ni) and bimetallic (CuCo and CuNi) nanoparticle supported on commercial graphite (CG) were prepared and characterized by TEM, EDS, XRD and Raman spectroscopy. The analysis revealed that the nanocomposites are made up of metallic nanoparticles with average particle size of 5–13 nm on the graphite matrix. The obtained results indicated that the Cu+Ni@CG catalyst exhibited high catalytic activity for furfural reduction, thus leaving Cu+Ni as the finest and cost effective catalyst for this study.     

Synthesis of phenol-formaldehyde resol resins using organosolv pine lignins

Lignin was extracted from white pine sawdust by organosolv-extraction using hot-compressed ethanol-water co-solvent. The optimum conditions for extracting lignin from the pine sawdust were found to be at 180 °C with ethanol-water solvent (1:1 wt/wt), where the lignin yield attained ca. 26% with a purity of ca. 83%. The lignin under such conditions was oligomers with a broad molecular weights distribution: M_n of 537, M_w of 1150 and polydispersity of 2.14. Bio-based phenol-formaldehyde resol resins were synthesized using the resultant lignin as the replacement of petroleum-based phenol at varying ratios from 25 to 75 wt.% by condensation polymerization catalyzed by sodium hydroxide. Upon heating the lignin-phenol-formaldehyde resols could solidify with a main exothermic peak at around 150-175 °C, typical of the conventional phenolic resol resins, and a secondary peak at 135-145 °C, likely due to the exothermic reactions between the free formaldehyde with phenol or lignin to form methylophenols. The replacement of phenol with lignin at a large ratio deferred the curing process, and the introduction of lignin in the resin formula decreased the thermal stability of the resin, leading to a lowered decomposition temperature and a reduced amount of carbon residue at elevated temperatures. For practical applications, it is suggested that the replacement ratio of phenol with lignin be less than 50 wt.%. The thermal stability can however be improved by purifying the lignin feedstock before the resin synthesis.     

Application of off-line pyrolysis with dynamic solid-phase microextraction to the GC–MS analysis of biomass pyrolysis products

Pyrolysis coupled with dynamic solid-phase micro extraction (Py-SPME) followed by GC–MS analysis was applied to the determination of volatile compounds evolved by a micro-scale off-line pyrolysis apparatus, in order to extend the information affordable with this type of analytical equipment. The Py-SPME method with a carboxen/PDMS fiber working in the retracted mode was tested on four biomass samples (switchgrass, sweet sorghum, corn stalk and poplar) for qualitative analysis of semi-volatile pyrolysis products and quantitative determination of main volatiles (C₁–C₄) pyrolysis products. The developed procedure allowed capturing and analysis of all GC analyzable compounds, without memory effects and with good peak resolution also for early GC-eluting compounds. Twelve main volatile pyrolysis products, including hydroxyacetaldehyde and acetic acid, were successfully quantified; in spite of the intrinsic variability introduced by dynamic SPME sampling, results were relatively accurate and consistent with literature data on bench pyrolysis reactors.     

An economic and environmental comparison of a biochemical and a thermochemical lignocellulosic ethanol conversion processes

With the world’s focus on rapidly deploying second generation biofuels technologies, there exists today a good deal of interest in how yields, economics, and environmental impacts of the various conversion processes of lignocellulosic biomass to transportation fuels compare. Although there is a good deal of information regarding these conversion processes, this information is typically very difficult to use on a comparison basis because different underlying assumptions, such as feedstock costs, plant size, co-product credits or assumed state of technology, have been utilized. In this study, a rigorous comparison of different biomass to transportation fuels conversion processes was performed with standard underlying economic and environmental assumptions so that exact comparisons can be made. This study looked at promising second-generation conversion processes utilizing biochemical and thermochemical gasification technologies on both a current and an achievable state of technology in 2012. The fundamental finding of this study is that although the biochemical and thermochemical processes to ethanol analyzed have their individual strengths and weaknesses, the two processes have very comparable yields, economics, and environmental impacts. Hence, this study concludes that based on this analysis there is not a distinct economic or environmental impact difference between biochemical and thermochemical gasification processes for second generation ethanol production.