Hydrogen dual-fuelling of compression ignition engines with emulsified biodiesel as pilot fuel

Dual-fuel compression ignition (CI) engine operation with hydrogen is a promising method of using hydrogen gas in CI engines via high-cetane pilot fuel ignition. However, hydrogen dual-fuel operation with neat pilot fuels typically produce: high NO_x emissions; and high combustion chamber pressure rise rates (leading to increased “Diesel knock” tendencies). While water-in-fuel emulsions have been used during normal CI engine operation to cool the charge and slow combustion rates in an effort to reduce NO_x emissions, these water-in-fuel emulsions have not been tested as pilot fuels during hydrogen dual-fuel combustion. In this work two water-in-biodiesel emulsions are tested as pilot fuels during hydrogen dual-fuel operation. Hydrogen dual-fuel operation generally produces at best comparable thermal efficiencies compared with normal CI engine operation, while the emulsified biodiesel pilot fuels generally increase thermal efficiencies when compared with the neat biodiesel pilot fuel during dual-fuel operation. There is also a clear reduction in NO_x emissions with emulsified pilot fuel use compared with the neat pilot fuel. The thermal efficiency increase is more apparent at higher engine speeds, while the NO_x reduction is more apparent at lower speeds. This is due to two conflicting effects (exclusive to emulsified pilot fuel) that occur in tandem. The first is the cooling effect of water vapourisation on the charge, while the second is the microexplosion phenomenon which enhances fuel-air mixing. The NO_x emission reduction is due to the emulsified pilot fuel lowering pressure rise rates compared with the neat pilot fuel, while the efficiency increase is due to a more homogeneous charge resulting from the violent microexplosion of the emulsified pilot fuel. Smoke, CO, HC and CO₂ emissions remain comparable to neat pilot fuel tests. Overall, emulsified pilot fuels can reduce NO_x emissions and increase thermal efficiencies, however not at the same instance and under different operating conditions. The general trends of reduced power output, reduced CO₂ and increased water vapour emission during hydrogen dual-fuel operation (with neat pilot fuels) are also maintained.     

Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquids： Effect of Specific Ions and Reaction Parameters

Caffeic acid phenethyl ester（CAPE） is a rare, naturally occurring phenolic food additive. This work systematically reported fundamental data on conversion of caffeic acid（CA）, yield of CAPE, and reactive selectivity during the lipase-catalyzed esterification process of CA and phenylethanol（PE） in ionic liquids（ILs）. Sixteen ILs were selected as the reaction media, and the relative lipase-catalyzed synthesis properties of CAPE were measured in an effort to enhance the yield of CAPE with high selectivity. The results indicated that ILs containing weakly coordinating anions and cations with adequate alkyl chain length improved the synthesis of CAPE. [Emim][Tf2 N] was selected as the optimal reaction media. The optimal parameters were as follows by response surface methodology（RSM）： reaction temperature, 84.0 °C; mass ratio of Novozym 435 to CA, 14︰1; and molar ratio of PE to CA, 16 ︰ 1. The highest reactive selectivity of CAPE catalyzed by Novozym 435 in [Emim][Tf2 N] reached 64.55%（CA conversion 98.76% and CAPE yield 63.75%, respectively）. Thus, lipase-catalyzed esterification in ILs is a promising method suitable for CAPE production.     

长碳链二元酸酯的合成及其物化性能

以杂多酸为催化剂、不同链长的二元酸为原料,合成了系列长碳链二元酸二元酯,考察了影响合成反应的因素及碳链长度对合成酯物化性能的影响. 结果表明,在回流温度160℃、醇/酸摩尔比3:1、催化剂用量为总质量1%、反应时间120 min、带水剂用量为总质量10%的条件下,酯化率达98%以上. 合成的酯具有良好的物化性能,其倾点最低为-74℃,闪点最高为258℃,粘度指数最大为187,优于现有商业化酯类润滑油基础油,达到现有航空润滑油基础油的标准. 随着碳链增长,合成酯粘度增大,增加醇碳链长度对粘度的影响大于增加酸碳链长度的影响.     

从四大酯类含量分析糟烧白酒

糟烧属其他香型白酒,是江南一带特有的一种白酒.目前,糟烧的发展状况较为缓慢,远远落后于其他白酒,主要表现在:工艺落后,出酒率低,口感不爽,放香不足,后味涩杂等方面.研究发现,糟烧的不足之处与糟烧中酯类的含量有很大关联.本实验重点将白酒中所含有的四大酯类(乙酸乙酯、丁酸乙酯、已酸乙酯和乳酸乙酯)作为切入点,对糟烧白酒中四大酯类进行分析检测,对提高糟烧白酒的质地及口感具有指导意义.结果显示糟烧中乳酸乙酯的含量占总酯的比例达74％,远远高于其他白酒中的相对含量.     

CO2对啤酒发酵过程中酵母生长代谢及酯的形成影响

啤酒加压发酵形成高浓度的CO2会使酿酒酵母生长受到抑制,导致主要风味物质酯的生成减少.CO2通过反馈抑制丙酮酸脱羧反应、降低基质和酵母胞内pH值、改变细胞膜的流动性和膜电势、抑制酵母的生长.乙酸酯类是乙酰辅酶和高级醇之间在醇酰基转移酶的催化作用下形成的.乙酰辅酶A、高级醇、醇酰基转移酶AATase活力是酯类形成的关键因素.发酵参数如温度和压力,特别是CO2对酯形成的研究是对酯形成机理的重要补充.然而,近年对CO2影响酯生成的研究并没有形成明确的机制理论.与乙酸酯相反,CO2可以刺激C6-C10中链脂肪酸乙酯(MCFA ethyl esters)的增加.CO2除了以底物形式参与酿酒酵母脂肪酸合成外,还能促进合成的进行,使脂肪酸积累,最终形成脂肪酸酯.     

二烯丙基双酚A催化改性酚醛型氰酸酯树脂的催化固化

研究了二烯丙基双酚A（DBA）催化改性酚醛型氰酸酯树脂（cy-5）,通过差示扫描量热法（DSC）、热重分析（TG）、冲击性能和动态热机械分析（DMA）测试,分析了改性树脂的热性能和力学性能。研究表明：DBA对cy-5有催化和增韧的双重作用,当DBA的添加量为5%（质量分数）时,催化效果最为明显,含10% DBA的改性树脂固化物的冲击强度达到7.41 kJ/m2,改性树脂固化物的玻璃化转变温度（Tg）和储能模量（E'）均有所降低,但幅度不大。     

方便面和方便米线中酞酸酯的污染现状研究

目的：了解方便面和方便米线中酞酸酯(PAEs)的污染状况。方法：样品用无水甲醇超声提取,上清液经干燥脱水过0.45μm滤膜过滤,采用毛细管气相色谱技术分析。结果：在采集的56袋市售方便面、25袋方便米线中检测到的邻苯二甲酸二丁酯和邻苯二甲酸二(2-乙基己基)酯的含量分别为：方便面调味酱料：未检出～59.38mg/kg、未检出～172.15mg/kg;方便面面饼：未检出～9.28mg/kg、未检出～1.08mg/kg;方便米线调味酱料：未检出～16.52mg/kg、未检出～44.75mg/kg。结论：方便面和方便米线食品存在不同程度的PAEs污染。     

氮化硼粒子增强氰酸酯树脂基复合材料的研究

在玻璃布增强氰酸酯树脂（CE）基复合材料中加入氮化硼(BN)粒子,制得CE/玻璃布/BN复合材料。研究了BN粒子含量对复合材料性能的影响。结果表明,经偶联剂处理的BN粒子使体系凝胶时间缩短,反应活性略有提高。BN粒子的加入可以明显提高复合材料的弯曲强度和层间剪切强度,在BN加入量为8 %时,复合材料的弯曲强度和层间剪切强度达到最大值,分别提高了5 %和36 %。加入BN粒子后,复合材料的起始热分解温度都较未填充体系有所提高,耐热指数升高,热稳定性相应提高。     

不同催化剂对松香季戊四醇酯合成的影响

针对目前制备松香季戊四醇酯的催化剂毒性较强或成本昂贵,且所需能耗大等问题,本文以高效、无毒、绿色环保、廉价的羧酸盐和碱性盐类化合物为催化剂催化松香和季戊四醇酯化反应合成松香季戊四醇酯,考察了催化剂种类和用量、n（松香）∶n（季戊四醇）、反应时间和反应温度等因素对酯化反应的影响,得出较佳的反应条件,即n（松香）∶n（季戊四醇）为1∶0.25、松香30.0g、催化剂硬脂酸锌为松香质量的0.20%、反应时间7h、反应温度250℃。在上述条件下,所得产物松香季戊四醇酯的酸值为18.07mg/g、软化点为94.7℃、色泽为9～10（铁钴法）。同传统催化剂氧化锌相比,在不使用其他助剂的情况下,所得产物色泽浅、软化点和酸值较低,且反应具有催化剂用量少、反应温度低、无需分离催化剂等优点。     

山嵛酸双酯基有机硅季铵盐的微波合成工艺及性能

以山嵛酸、N-甲基二乙醇胺以及γ-氯丙基三甲氧基硅烷为主要原料,分别经过酯化和季铵化反应两步合成了一种超长碳链的双酯基有机硅季铵盐,并通过单因素、正交试验得到了微波法合成目标产物的最优工艺条件为：设置微波功率为800W,物料摩尔比为n（硅烷）∶n（酯胺）=1.2∶1,反应温度为170℃,溶剂用量为m（溶剂）∶m（原料）=0.8∶1,反应时间为12h,产品产率达96.60%。此方法克服了长链叔胺季铵化过程中普遍耗时过长的困难,提高了反应速率,而且实验重复性良好。实验中采用红外光谱、核磁共振氢谱对中间体及目标产物的结构进行了表征,与预期结果一致;建立了高效液相色谱-蒸发光散射检测器（HPLC-ELSD）测定季铵盐纯度的方法,基线稳定,峰型良好,产品纯度达98.77%,具有一定的参考价值。性能测试结果表明：对比DC-5700,目标产物具有良好的热稳定性,优异的乳化及增溶性能;其水溶液的临界胶束浓度为1.81mmol/L,表面张力（γ_CMC）为49.4mN/m。