Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water

Ball milling leads to a considerable reduction in cellulose particle size and crystallinity, as well as a significant increase in the specific reactivity of cellulose during hydrolysis in hot‐compressed water (HCW). Cryogenic ball milling for 2 min also results in a significant size reduction but only little change in cellulose crystallinity and specific reactivity during hydrolysis. Therefore, crystallinity is the dominant factor in determining the hydrolysis reactivity of cellulose in HCW while particle size only plays a minor role. Ball milling also significantly influences the distribution of glucose oligomers in the primary liquid products of cellulose hydrolysis. It increases the selectivities of glucose oligomers at low conversions. At high conversions, the reduction in chain length plays an important role in glucose oligomer formation as cellulose samples become more crystalline. An extensive ball milling completely converts the crystalline cellulose into amorphous cellulose, substantially enhancing the formation of glucose oligomers with high degrees of polymerization. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Comparative studies of oil compositions produced from sawdust,rice husk,lignin and cellulose by hydrothermal treatment

The objective of this study is to investigate the distribution of products, i.e. liquid, gas and solid from wood (sawdust) and non-wood biomass (rice husk), and major biomass components, i.e. lignin, cellulose produced by hydrothermal treatment (280 °C for 15 min) and analysis of liquid hydrocarbons (oils) for the differences in the hydrocarbon composition with respect to feed material. Cellulose showed the highest conversion among the four samples investigated in the present study. Sawdust and rice husk has almost similar conversions. Liquid products were recovered with various solvents (ether, acetone, and ethyl acetate) and analyzed by GC–MS. The oil (ether extract) from the hydrothermal treatment of cellulose consisted of furan derivatives whereas lignin-derived oil contained phenolic compounds. The compositions of oils (ether extract) from sawdust and rice husk contained both phenolic compounds and furans, however phenolic compounds were dominant. Rice husk derived oil consists of more benzenediols than sawdust derived oil. The volatility distribution of oxygenated hydrocarbons were carried out by C-NP gram and it showed that the majority of oxygenated hydrocarbons from sawdust, rice husk and lignin were distributed at n-C₁₁, whereas they were distributed at n-C₈ and n-C₁₀ in cellulose-derived oil. The gaseous products were carbon dioxide, carbon monoxide, methane in sawdust, rice husk, lignin and cellulose. In addition to this, ethylene, ethane and propane were observed for sawdust, rice husk and lignin. The major gas product was carbon dioxide for all samples.     

Ball milling promoted direct liquefaction of lignocellulosic biomass in supercritical ethanol

In the present work, ball milling was applied for the pretreatment of lignocellulose to obtain high conversion and bio-oil yield in supercritical ethanol. Ball milling substantially decreased the crystallinity and particle size of lignocellulose, thereby improving its accessibility in ethanol solvent. An increased bio-oil yield of 59.2% was obtained for the ball milled camphorwood sawdust at 300°C, compared with 39.6% for the original lignocellulose. Decreased crystallinity significantly benefited the conversion of the cellulose component from 60.8% to 91.7%, and decreased particle size was beneficial for the conversion of all components. The obtained bio-oil had a high phenolic content, as analyzed by gas chromatography-mass spectrometry. Methoxylation and retro-aldol condensation were observed during alcoholysis, and the reaction pathways of lignocellulose in supercritical ethanol were attributed to the action of free radicals.     

锯木屑在超临界水中气化制氢过程的主要影响因素

以锯木屑混合羧甲基纤维素钠（CMC）为反应原料,利用连续管流反应器,在反应器外壁面温度稳定在650 ℃条件下,对反应压力在17.5～30 MPa,反应停留时间在14.4～50 s,浓度范围为4%～9%（质量分数）的湿生物质浆液进行了超临界水气化制氢实验研究,讨论了气化过程的主要参数压力、温度、反应停留时间以及物料浓度对气化结果的影响.锯木屑在超临界水中接近完全气化,生成气体产物的主要成分是H₂、CH₄、CO、CO₂以及少量的C₂H₄和C₂H₆,气化产物中的H2含量可以超过40%.同时,实现了气化反应液体产物的循环利用.     

Structural changes and enhanced accessibility of natural cellulose pretreated by mechanical activation

A kind of natural cellulose, bleached pine pulp (BPP), was pretreated by mechanical activation (MA) using a self-designed stirring ball milling. The effect of MA pretreatment on the dissolving capacity and molecular chain structure of BPP were investigated by the determination of alkaline solubility (Sa) and degree of polymerization (DP). In addition, the changes in crystal structure of MA-pretreated BPP with different milling times were qualitatively and quantitatively measured by X-ray diffraction and Fourier transform infrared spectroscopy, and the morphology modification was observed by scanning electron microscopy. It was found that MA significantly increased the Sa and reduced the DP of BPP, contributing to the destruction of inter- and intramolecular hydrogen bonds and macromolecular chains in cellulose. The stable crystal structure of BPP was also remarkably damaged during MA processing, resulting in the variation of surface morphology, the increase of amorphous region ratio and hydrogen bond energy, and the decrease in crystallinity and crystalline size, which efficiently increased the accessibility of natural cellulose and would have positive effects on subsequent treatments. The crystalline form of natural cellulose was not changed by MA, and no new functional groups generated during milling.     

CONCENTRATED ACID CONVERSION OF PINE SOFTWOOD TO SUGARS. PART I: USE OF A TWIN-SCREW REACTOR FOR HYDROLYSIS PRETREATMENT

The first stage of a two-step concentrated sulfuric acid process that converts softwood sawdust to sugars has been explored. The research focuses on the ability of an in-house custom fabricated corotating twin-screw reactor (TSR) to effectively break down and solubilize crystalline cellulose into low molecular weight carbohydrates. Based on design of experiment (DOE) screening results, a four-level, two-factor experimental model building DOE was undertaken. Solid sawdust conversion to liquid, screw torque, and TSR exit pressure were measured or recorded at each experimental condition to yield percent conversion of solids, processed material viscosity, and material energy requirements. Thereafter, model quadratic equations were fitted to the experimental data and found to be statistically significant. Based on data obtained in the DOE the process was optimized to establish a base case operating condition. The acid-treated product made at base case twin-screw operating conditions showed a 38.2% conversion of dry sawdust solids to soluble liquids. The dry solids conversion reduced 73.8% of all hemicellulose and 44.4% of all cellulose to soluble monomers and oligosaccharides.     

球磨改性热解炭吸附磺胺甲唑

针对热解炭颗粒大、表面活性弱、吸附能力差的问题,本文提出了一种机械球磨表面改性方法,探讨了不同球磨改性参数下热解炭对磺胺甲唑（SMZ）的吸附效果。以废橡胶连续热解炭为原料,采用不锈钢球磨制得具有不同表面性质的球磨炭,分析了球磨前后热解炭的结构、表面性质及表面形貌,并对比了球磨改性前后的SMZ吸附性能。结果表明,球磨改性过程可以有效改善废轮胎热解炭结构及表面性质,球磨处理2h的热解炭对SMZ的吸附效果最好,吸附量达到59.37mg/g,吸附动力学符合伪二级吸附模型。     

Char and Coke Formation as Unwanted Side Reaction of the Hydrothermal Biomass Gasification

The hydrothermal biomass gasification is a promising technology to produce hydrogen and/or methane from wet biomass with a water content of ≥ 80 % (g/g). In the process, the coke formation usually is very low, but already low amounts may cause problems like, e.g., fouling in the heat exchanger. To learn more about the product formation, the results of the hydrothermal treatment (at 400, 500, 600 °C and 1 h) of different biomass feedstocks (artichoke stalk, pinecone, sawdust, and cellulose as model biomass) in a microreactor are compared. The gas composition and the total organic carbon content of the aqueous phase were determined after reaction. The gas formation rises with increasing temperature. The formation of carbon deposits and their characterization has been investigated by scanning electron microscopy (SEM). The variation of the solid morphology during the hydrothermal conversion is discussed based on chemical pathways occurring during hydrothermal biomass degradation.     

产氢用生物质球磨预处理工艺的优化试验

本研究采用球磨法对产氢用生物质进行预处理,以酶解后还原糖得率作为考察指标,采用电镜对粉碎后物料进行分析,并利用DPS 7.05分析软件进行试验设计和数据分析,对球磨处理工艺进行优化。分析了原料初始粒径、球料比和球磨时间对酶解糖化过程的影响,得出球料比为显著影响因素,球磨预处理最佳工艺参数为：原料初始粒径0.45 mm,球料比20∶1,球磨时间1 h,在此条件下,还原糖得率为74.50%。     

产氢用生物质球磨预处理工艺的优化试验

本研究采用球磨法对产氢用生物质进行预处理,以酶解后还原糖得率作为考察指标,采用电镜对粉碎后物料进行分析,并利用DPS 7.05分析软件进行试验设计和数据分析,对球磨处理工艺进行优化。分析了原料初始粒径、球料比和球磨时间对酶解糖化过程的影响,得出球料比为显著影响因素,球磨预处理最佳工艺参数为:原料初始粒径 0.45 mm,球料比20∶1,球磨时间 1 h,在此条件下,还原糖得率为 74.50%。     

木质纤维素预处理技术研究进展

木质纤维素转化燃料乙醇一般需要经过原料预处理、酶水解和发酵过程。由于木质纤维原料化学结构复杂、直接酶解效率非常低,一般在酶水解之前需要进行适当的预处理以打破其致密结构,增加纤维表面积,提高后续纤维素酶的可及性。预处理程度直接影响纤维底物后续酶水解的效果。本文在木质纤维素常用预处理技术分析的基础上,重点讨论了3种相对高效的预处理技术：微波辅助离子液体预处理、两阶段深度共熔溶剂（DES）预处理和氯化铁预处理技术,分析了它们的优势、不足及发展现状。文中指出微波辅助离子液体预处理可有效解构木质素和半纤维素,破坏纤维素结晶区域,利于后续酶解,但微波加热过程会使离子液体分解和部分底物碳化。两阶段DES预处理可有效提高酶水解效率,但是预处理后原料中残留的DES可能会对后续反应中纤维素酶和微生物产生抑制作用。氯化铁预处理可有效破坏木质素与碳水化合物间的结合键,脱除底物中的半纤维素,而对木质素和纤维素降解较少,具有很好的发展前景。由于单一预处理技术的局限性,寻求低成本高效的联合预处理技术将是未来重点发展的方向。     

Simultaneous wet ball milling and mild acid hydrolysis of rice hull

BACKGROUND: Rice hull, an abundant residue but a big issue for the rice processing industry, has the potential to serve as a feedstock for production of ethanol because of its lignocellulosic composition. Simultaneous wet ball milling and mild acid hydrolysis of rice hull was studied in this work. RESULTS: Ball milling with 150 small stainless steel beads and rotation speed of 600 rpm in citrate solvent of pH 4 was the optimal condition for hydrolysis, and the yield of sugar increased with increased milling time. Corresponding structure transformations before and after milling analyzed by X‐ray diffraction (XRD), environmental scanning electron microscopy (ESEM) and transmission fourier transform infrared spectroscopy (FT‐IR) clearly indicate that this hydrolysis could be attributed to the crystalline and chemical structure changes of cellulose in rice hull during ball milling in mild acid solvent. CONCLUSION: This combined treatment of ball milling and citrate solvent greatly changed the crystalline and chemical structure and continuously generated sites accessible to citrate solvent, thus enabling hydrolysis of the rice hull. Copyright © 2009 Society of Chemical Industry     

Ru/CNT催化纤维二糖加氢制备山梨醇的机理及动力学

针对纤维素的转化,研究了以钌碳纳米管(Ru/CNT)为催化剂,纤维素模型分子纤维二糖催化加氢制备山梨醇的反应。通过对反应产物的分析,考察了纤维二糖转化生成山梨醇的反应机理,建立了纤维二糖催化加氢的动力学模型。并根据实验数据,拟合得到纤维二糖催化加氢反应各步的反应数率常数和表观活化能,其中,纤维二糖水解活化能为147.1 KJ·mol^-1;纤维二糖部分加氢活化能为73.8 KJ·mol^-1。纤维二糖催化加氢反应模型的建立,为纤维素资源的高效利用提供了重要的基础数据。     

The effect of high energy milling on the catalytic behaviour of manganese dioxide

A technique of dry high energy milling has been used to increase the catalytic activity of naturally occurring manganese dioxide powder. The effect of the basic milling parameters (ball charge, milling time and milling atmosphere) has been examined. The subsequent catalytic activity of the manganese dioxide powder has been assessed by quantitative measurement of the oxidation of carbon monoxide over a range of temperatures. A surface area increase alone did not explain the results, and hence a change in defect structure is suspected. The activity of a high purity synthetic manganese dioxide powder was reduced by the milling treatment.     

氧化铋掺杂纳米二氧化锰/活性炭复合电极

首次应用机械振动研磨法在室温条件制备纳米活性炭电极材料,经过30 min研磨后,得到了粒度分布在30～50 nm之间的纳米活性炭（nm-AC）,研究表明,这种纳米活性炭的结晶性得到了明显增强和改善,且孔径分布更趋于合理。并用溶胶-凝胶方法合成了掺杂氧化铋的纳米二氧化锰（nm-Bi-MnO ₂）,将其与制备的纳米活性炭制成超级电容器所需的复合电极材料。与10%二氧化锰复合的纳米活性炭电极具有最佳的充放电性能,尤其是在掺杂氧化铋的情况下比电容能量达到308 F·g^-1,且随着电流增大没有显著的衰减。与此同时,用机械振动研磨法将二氧化锰与活性炭的混合物进行研磨改性,电化学分析表明,经机械振动研磨改性的二氧化锰的比电容相对较大,具有进一步提高电极材料性能的潜力。     

Hydrogenation of carbon monoxide under mechanical activation conditions

The work focuses on the hydrogenation of carbon monoxide over solid catalysts undergoing mechanical activation by ball milling. The rate of carbon monoxide conversion at individual ball impacts was estimated by measuring the impact frequency, the mass of powders involved in individual impacts and their duration. The rate of the mechanochemical hydrogenation process was compared with the one of the corresponding thermal process. An enhancement of the catalyst activity under mechanical activation conditions is observed.     

Hydrothermal catalytic conversion of biomass for lactic acid production

The production of lactic acid has increased owing to growing polymer markets, increased demand in the chemical sector and many applications in the food industry. Biomass hydrothermal decomposition is potentially a method for lactic acid production. To obtain a higher yield of lactic acid, the influence of metal ions (Zn(II), Ni(II),Co(II) and Cr(III)) on biomass decomposition in sub‐critical water (T = 300 °C) was investigated and the catalyst function in the complex reaction network of biomass degradation was discussed. In comparison with a non‐catalytic process, the addition of 400 ppm Ni(II) catalyst increased the yield of lactic acid from 3.25% to 6.62% at 300 °C and 120 s for microcrystalline cellulose. The lactic acid yield for glucose was 9.51% for 400 ppm Co(II) catalyst at 300 °C and 120 s. In the case of Cr(III) and Ni(II), the conversion of maize straw, sawdust and rice husk first increased, and then decreased from 0 to 800 ppm. For catalyst Cr(III), Zn(II) and Ni(II), the conversion of wheat bran indicated a decreasing trend. Transition metal ions have a great influence on raw materials conversion to lactic acid. In the conversion of pyruvaldehyde to lactic acid, the ionic catalyzed Cannizzaro‐type reaction would take place. Copyright © 2007 Society of Chemical Industry     

离子液体介质中纤维素资源转化研究进展

木质纤维素是地球上最丰富的可再生有机碳资源,将其高效转化为化学品或燃料,对缓解全球能源危机和解决环境污染问题具有重要意义。离子液体因对木质纤维素具有独特的溶解性能,近年来作为新型溶剂在生物质转化中获得广泛应用。综述了离子液体用于木质纤维素预处理及化学转化的最新研究进展,包括纤维素溶解、木质纤维素组分分离、纤维素水解制葡萄糖、六碳糖及纤维素催化转化制5-羟甲基糠醛以及碳水化合物的其他转化途径等,同时对基于离子液体平台的生物质转化技术存在的挑战、未来发展趋势及工业化前景进行了展望。     

Hydrolysis of birch wood by simultaneous ball milling,dilute citric acid,and fungus Penicillium simplicissimum treatment at room temperature

In this study, birch wood chips were treated in one‐step ball milling (BM) hydrolysis with dilute citric acid and fungus Penicillium simplicissimum at room temperature and atmospheric pressure. An efficient conversion process for the production of fermentable sugars from woody biomasses using wet BM system was developed, in which wood lignocellulose was hydrolyzed into reducing sugars with the total yield of 245.3 mg/g wood. The concentrations of several major substances in the hydrolyzate were discussed in detail. The yields of the monomeric sugars were notably increased in the presence of fungus P. simplicissimum. Corresponding structure transformations before and after milling were analyzed by X‐ray diffraction, UV spectroscopy, transmission Fourier transform infrared spectroscopy, and environmental scanning electron microscopy clearly indicated that this combined treatment could be attributed to the crystalline and chemical structure changes of wood lignocellulose during BM. When compared with traditional method of BM, this work showed a more simple, novel, and environmental friendly way in mechanochemical treatment of lignocellulosic biomass, especially woody biomass. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of High‐Energy Ball Milling and Silica Fume Addition in BaCO3–Al2O3. Part I: Formation of Cementing Phases

The effects of high‐energy ball milling and subsequent calcination on the formation of barium aluminate cementing phases using mixtures of Al₂O₃ and BaCO₃ were investigated. Silica fume was further added in the raw mixtures to observe its role on the cementing phase formation. Results indicated that the decomposition temperature of BaCO₃ lowered remarkably with the increase in milling time. Barium aluminate cements with grain size in nanometer range were obtained from high‐energy ball‐milled raw mixtures. X‐ray diffraction (XRD) results confirmed several crystalline barium‐silicate and barium aluminate phases present. Formation of crystalline BaO·Al₂O₃ phase was observed between 1000°C and 1100°C in the raw mixtures, which were obtained in amorphous state after milling for 5 h. This temperature is at least 300°C lower than that used in the traditional solid‐state method. Fume SiO₂ additions resulted in BaO·Al₂O₃·2SiO₂ (celsian) formation which acted as a retarder, provides more workability and mechanical strength.