木质素在超临界甲醇和乙醇溶剂中液化过程分析

通过研究木质素分别在超临界甲醇和乙醇溶剂中的液化过程，分析反应温度（260～340℃）及反应时间（0～120min）对木质素在两种溶剂中的转化率、生物油收率及其组分差异的影响。实验表明，木质素在超临界乙醇中的转化率及产物收率均高于甲醇。当反应温度340℃，反应时间60min，木质素在超临界乙醇中的转化率和生物油收率比在甲醇中分别提高了16.23%和11.54%，残渣收率降低了16.23%。通过GC-MS和FTIR对生物油和残渣分析，发现生物油组分中芳香族化合物相对含量较高，在甲醇和乙醇溶剂中分别达到66.13%和58.84%；随着反应时间的延长，甲醇溶剂中残渣的醚键官能团逐渐增强，而在乙醇溶剂中则先增强后减弱。分析认为在木质素降解过程中，超临界乙醇和甲醇均可产生氢自由基作为供氢体，攻击木质素及其大分子片段中的官能团，同时使液化产物中的活性片段减活，减弱重聚合反应，从而更利于芳烃产物的生成。而甲醇在液化过程中容易与木质素断键产生的苯酚中间体发生脱氢缩合反应，通过醚键聚合产生长链芳香族化合物，形成残渣，降低生物油收率。     

Effects of ball milling on structural changes and hydrolysis of lignocellulosic biomass in liquid hot-water compressed carbon dioxide

Mechanical activation is an effective method for destroying the crystalline structure. Biomass, especially its hemicellulose, can be degraded in the green solvent of liquid hot-water compressed carbon dioxide. To improve the degradation of crystalline cellulose in liquid hot-water compressed carbon dioxide, pretreatment of camphorwood sawdust by mechanical activation with a stirring ball mill was studied. Ball milling parameters and their effects on structure were determined by SEM, XRD and FT-IR. The influence of milling parameters on cellulose conversion can be ranked as follows: ball milling speed>activation time>the mass ratio of ball to biomass. The optimum milling condition was obtained at ball milling speed of 450 rpm and mass ratio of 30: 1 of ball to biomass for 2 h. In this condition, cellulose crystallinity of sawdust decreased from 60.93% to 21.40%. The cellulose conversion was 37.8%, which was nearly four times of raw material (10.2%). The glucose yield in the hydrolysate was 1.49 g·L^?1, which was nearly three times of that of raw material. It showed mechanical activation can destroy the crystalline structure of cellulose to promote degradation and the damage of lignocellulosic internal structure caused by ball milling is irreversible.     

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     

羰基镍粉焙烧制备高纯度微米氧化亚镍粉体的研究

以羰基镍粉为原料,采用焙烧法制备了氧化亚镍,并将其球磨后得到微米粉体。采用热重-差示扫描量热仪（TG-DSC）研究了羰基镍粉在空气气氛中加热时的氧化行为,利用激光粒度分析仪、等离子体光谱仪、X射线衍射仪（XRD）和扫描电镜（SEM）等分析了样品结构、成分和形貌。结果表明：空气和氧气两种气氛对产物纯度影响不明显。在两种载气条件下,通过优化焙烧温度和焙烧时间（焙烧温度为700 ℃、焙烧时间为2 h、载气流量为1.5 L/min）,羰基镍粉可直接焙烧制备得到纯度为100%、结晶度高的面心立方体氧化亚镍,球磨后得到粒度为4~19 μm的类球形微米氧化亚镍粉末。制备过程具有工艺简单、环境友好的特点。     

Effects of particle size on the fast pyrolysis of oil mallee woody biomass

This study aims to investigate the effects of biomass particle size (0.18-5.6 mm) on the yield and composition of bio-oil from the pyrolysis of Australian oil mallee woody biomass in a fluidised-bed reactor at 500 °C. The yield of bio-oil decreased as the average biomass particle size was increased from 0.3 to about 1.5 mm. Further increases in biomass particle size did not result in any further decreases in the bio-oil yield. These results are mainly due to the impact of particle size in the production of lignin-derived compounds. Possible inter-particle interactions between bio-oil vapour and char particles or homogeneous reactions in vapour phases were not responsible for the decreases in the bio-oil yield. The bio-oil samples were characterised with thermogravimetric analysis, UV-fluorescence spectroscopy, Karl-Fischer titration as well as precipitation in cold water. It was found that the yields of light bio-oil fractions increased and those of heavy bio-oil fractions decreased with increasing biomass particle size. The formation of pyrolytic water at low temperatures (<500 °C) is not greatly affected by temperature or particle size. It is believed that decreased heating rates experienced by large particles are a major factor responsible for the lower bio-oil yields from large particles and for the changes in the overall composition of resulting oils. Changes in biomass cell structure during grinding may also influence the yield and composition of bio-oil.     

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%。     

浒苔热裂解制取生物油的试验

为了解决化石燃料短缺以及沿海浒苔过度繁殖所带来的问题,提出将浒苔做原料通过直接热裂解的方法转化为生物油。本文在实验室组装的反应器内系统地考察了温度、时间以及原料粒径对产物收率以及产物分布的影响。实验结果表明:实验原料的粒径越小,其生物油的产率越高;当反应温度为350℃,反应时间为40min,原料粒径为60目的最优条件下,生物油的产率高达30.5%,不凝气产率可达13.9%。对产物进行分析发现:生物油主要包含醛、酮、酚类以及醇、羧基酸、酯类等化合物;不凝气主要由CO2、CO、CH4以及C2～C5的小分子烃类组成。     

Optimized experimental design for natural clinoptilolite zeolite ball milling to produce nano powders

Nano powder of natural clinoptilolite zeolite was mechanically prepared by using a planetary ball mill. Statistical experimental design was applied to optimize wet and dry milling of clinoptilolite zeolite. To determine appropriate milling conditions with respect to the final product crystallinity, particle size and distribution, different milling parameters such as dry and wet milling durations, rotational speed, balls to powder ratio and water to powder ratio (for the wet milling) were investigated. Laser beam scattering technique, scanning electron microscopy and X-ray diffraction analyses were carried out to characterize samples. Results showed that larger than 1 mm particle size of clinoptilolite powder may mechanically be reduced into the size range of less than 100 nm to 30 μm by means of planetary ball milling.     

Ru/C催化作用下生物油在超临界乙醇中的提质

使用了两步加氢-超临界提质以及一步超临界提质两种方法对生物油进行提质,并进行了溶剂回收利用。实验结果表明经过这两种提质方法,生物油的物化性质均得到有效提升,提质后生物油中酸、酮和酚的相对含量明显下降,而醇、醚和酯类等理想产物的相对含量有显著上升。根据每步产物的GC-MS结果,对提质过程中所发生的反应进行了推测。相对于一步法提质所得到生物油,两步提质法所得到的提质生物油中醇和醚类的相对含量略高而酮、酚和酯类的相对含量略低。同时,相比于一步超临界提质,两步加氢-超临界提质过程中乙醇的消耗量有所降低。溶剂的回收利用在降低生物油提质所需要的乙醇含量的同时提高了提质产物中酯类的相对含量,这表明在较低的醇油比条件下超临界提质仍然是一种有效的生物油提质方法。     

Preparation and Characterization of Nano structured Materials from Fly Ash: A Waste from Thermal Power Stations, by High Energy Ball Milling

The Class F fly ash has been subjected to high energy ball milling and has been converted into nanostructured material. The nano structured fly ash has been characterized for its particle size by using particle size analyzer, specific surface area with the help of BET surface area apparatus, structure by X-ray diffraction studies and FTIR, SEM and TEM have been used to study particle aggregation and shape of the particles. On ball milling, the particle size got reduced from 60 μm to 148 nm by 405 times and the surface area increased from 0.249 m²/gm to 25.53 m²/gm i.e. by more than 100%. Measurement of surface free energy as well as work of adhesion found that it increased with increased duration of ball milling. The crystallite was reduced from 36.22 nm to 23.01 nm for quartz and from 33.72 nm to 16.38 nm for mullite during ball milling to 60 h. % crystallinity reduced from 35% to 16% during 60 h of ball milling because of destruction of quartz and hematite crystals and the nano structured fly ash is found to be more amorphous. Surface of the nano structured fly ash has become more active as is evident from the FTIR studies. Morphological studies revealed that the surface of the nano structured fly ash is more uneven and rough and shape is irregular, as compared to fresh fly ash which are mostly spherical in shape.     

Recycling and application of wasted polytetrafluoroethylene via high‐energy ball milling technology for nitrile rubber composites preparation

Wasted polytetrafluoroethylene fibers were recycled using high‐energy ball milling technique, and the recylced polytetrafluoroethylene (r‐PTFE) was employed to prepare nitrile rubber (NBR)/r‐PTFE composites. The structure of r‐PTFE and properties of NBR/r‐PTFE composites were investigated by polarized optical microscope, laser particle size analyzer, differential scanning calorimetry, and scanning electron microscopy, respectively. The results show that increasing the milling time from 4 to 7 h leads to decreasing the average particle size, the degree of crystallinity and the number‐average molecular weight of r‐PTFE, whereas no obvious change is found by further prolonging the milling time. It is also clear that the NBR/r‐PTFE composite with the r‐PTFE obtained from a longer milling time possesses a higher mechanical and solvent resistance property. Compared with pure NBR, NBR/r‐PTFE composites with r‐PTFE for 7 h milling show a 21.9% increase in modulus at 300% and 27.8% decrease in swelling index. POLYM. ENG. SCI., 56:643–649, 2016. © 2016 Society of Plastics Engineers     

Effect of high-energy ball milling on the microstructure and properties of ultrafine gradient cemented carbides

Planetary low-temperature high-energy ball mill was used for preparing the mixed powders with different particle sizes by adjusting the milling time. The ultrafine grain gradient cemented carbides were prepared by sinter-HIP treatment. The effects of milling time on the gradient formation, grain growth, and mechanical properties of ultrafine grain gradient cemented carbides were investigated. The results show that the high-energy ball milling cannot effectively reduce the particle size of mixed powder with short milling time. In addition, the particle size of the mixed powder is significantly reduced, while the specific surface area is significantly increased when the ball milling time exceeds 25 hours. The gradient layer thickness and the grain size increase at the beginning and then decrease when the mixed powder particle size was decreased. Simultaneously, the density, hardness, and fracture toughness of the alloy increase gradually. On the contrary, the number of WC with abnormal grain growth is significantly increased. The thickness of the gradient layer reached 32 μm, and the mean WC grain size is 314 nm. Based on the analyzed results, an optimized gradient layer thickness, grain size, density, and hardness can be obtained when the ball milling time is 35 hours.     

氮化硅粉体的行星式球磨工艺研究

主要研究了各种球磨工艺参数在行星式球磨过程中对粉料的粒度及形貌的影响。由于超细粉碎过程中特有的团聚现象，当颗粒尺寸达到极限值时，进一步延长球磨时间，反而使球磨的效果变差，降低球磨效率。通过对氮化硅粉体行星球磨过程的分析，研究了不同球磨工艺参数(如料球比、球磨转数、球磨时间等)对氮化硅粉料球磨效果的影响，从而优化行星球磨工艺参数。     

Catalytic upgrading of fast pyrolysis oil over hzsm-5

The upgrading of bio-oil, obtained by fast pyrolysis of maple wood, was studied over HZSM-5 in a fixed bed micro-reactor operated at atmospheric pressure and in the temperature range 330-425°C. The objective of upgrading was to maximize the amount of organic distillate product with a high yield of aromatic hydrocarbons. A maximum organic distillate of 38 wt.% of bio-oil, which represented 28.6 wt.% of wood, was obtained at 370°C. The yield of aromatic hydrocarbons was 19.9 wt.% of wood. Above 400°C, nearly 50 wt.% of the bio-oil was converted to coke and char. The conversion of non-volatile components of the bio-oil (pitch) to volatiles was at a maximum of 68 wt. % at 370°C. However, when the bio-oil was co-processed with tetralin, the maximum conversion of non-volatiles increased to 86 wt.% at 410°C and the amounts of coke and char decreased. The yield of aromatic hydrocarbons also decreased to a maximum of 10.3 wt. % of wood. The role of tetralin was mainly as a diluent and not as a hydrogen donor solvent.     

研磨方式对电瓷坯料粒度分布及性能的影响

比较了单一球磨(BM)和球磨与搅拌式砂磨相结合(BM +SM)两种研磨方法对电瓷坯料粒度分布及其性能的影响.用激光粒度分析仪测试了不同试样的粒度分布,用XRD和SEM表征了烧结试样的物相组成和显微结构.结果表明:球磨8h后再经过搅拌式砂磨机研磨1 min的坯料特征粒度与球磨14 h的坯料特征粒度相比,D10和D50较为接近,但D90和 D99均明显减小;球磨8h后再砂磨1 min的坯料干坯强度提高了14％,烧成后瓷质抗弯强度和电气强度分别提高了约10％和8.5％,试样显微结构中晶粒尺寸较小,气孔率低且气孔尺寸较小,形状多呈规则的球状.     

群青颜料的球磨及改性研究

采用实验室自制球磨机,以乙醇为溶剂对群青颜料进行球磨,制备了不同粒径的群青颜料色浆,用于随后的改性研究.分析了球磨时间、球料比、色浆浓度、分散剂用量、磨球大小和级配对群青颜料粒径及其分布的影响.用硅烷偶联剂3-氨丙基三乙氧基硅炕(APTEs)对不同粒径群青颜料进行表面改性,探讨了改性颜料粒径大小与体系稳定性、印花性能的关系.实验结果表明,颜料粒径越小,体系分散稳定性越好;改性后颜料耐酸性随粒径减小而降低;印花织物的干摩擦牢度随粒径减小而升高,但湿摩擦牢度随粒径减小有降低的趋势.     

Pyrolytic characteristics of Jatropha seedshell cake in thermobalance and fluidized bed reactors

Pyrolytic kinetic parameters of Jatropha seedshell cake (JSC) were determined based on reaction mechanism approach under isothermal condition in a thermobalance reactor. Avrami-Erofeev reaction model represents the pyrolysis conversion of JSC waste well with activation energy of 36.4 kJ mol^?1 and frequency factor of 9.18 s^?1. The effects of reaction temperature, gas flow rate and feedstock particle size on the products distribution have been determined in a bubbling fluidized bed reactor. Pyrolytic bio-oil yield increases up to 42 wt% at 500 °C with the mean particle size of 1.7 mm and gas flow rate higher than 3U _mf , where the maximum heating value of bio-oil was obtained. The pyrolytic bio-oil is characterized by more oxygen, lower HHVs, less sulfur and more nitrogen than petroleum fuel oils. The pyrolytic oil showed plateaus around 360 °C in distribution of components’ boiling point due to high yields of fatty acid and glycerides.     

滇池蓝藻在亚/超临界乙醇中热化学催化液化制备生物油及其特性

在高压反应釜中,以亚/超临界乙醇为液化介质、以SO42-/ZrO2为催化剂催化液化滇池蓝藻制备生物油,考察了反应温度、反应时间、催化剂用量、料液比等对蓝藻液化效果的影响. 正交实验表明,反应温度270℃、反应时间40 min、催化剂SO42-/ZrO2加入量为蓝藻质量的2%、蓝藻与乙醇比为1:15 g/mL是最佳的条件,在此条件下液化率为87.46%,油产率为63.32%. 分析了生物油的特性和组分,生物油是一种组成复杂的有机混合物,其主要成分为十六烷酸乙酯.     

Amorphous α-Tricalcium Phosphate: Preparation and Aqueous Setting Reaction

The mechanical and setting properties of calcium phosphate cements are considerably determined by the pretreatment of the constituents. In this report we show for the first time that prolonged high-energy ball milling of α-tricalcium phosphate (α-TCP) led to mechanically induced phase transformation from the crystalline to the amorphous state. The amorphous material demonstrated a high reactivity such that the time for substantially complete conversion of α-TCP to calcium-deficient hydroxyapatite in 2.5% Na₂HPO₄ solution decreased from about 20 h (1 h of grinding in ethanol, 85% relative crystallinity) to 4–6 h for a material with a crystallinity of 8% (24 h of grinding). This reactivity could be attributed to an increased thermodynamic and kinetic solubility of the ground materials. Mechanically activated α-TCP cements were produced with compressive strengths of up to 80 MPa and setting times of 5–16 min. The effect of reactant preparation and cement mixing parameters on the physical and chemical properties of mechanically activated α-TCP cement was investigated. By comparing cements of similar porosity and degree of conversion it was demonstrated that apatite specific surface area has a strong influence on cement mechanical performance, which highlights the importance of this previously overlooked parameter in improving strength.