30 research outputs found
Oxidation Esterification of Acetol with Methanol to Methyl Pyruvate over Supported Au Catalysts
本论文以生物质衍生化合物羟基丙酮的选择性氧化酯化制备高附加值丙酮酸甲酯为目标,围绕醇氧化酯化制备酯类化合物的过程展开讨论,针对选择性氧化酯化反应中催化剂酸碱性的影响进行研究,寻求能有效催化羟基丙酮转化制备丙酮酸甲酯的多功能催化剂。 本文比较了具有不同载体的负载型金催化剂催化反应性能,并用Hammett指示剂法对各个载体酸碱度进行测定,结果表明,酸碱两性催化剂催化性能优于单一酸碱性催化剂,以具有适宜酸碱两性的HAP载体上负载Au得到的Au/HAP催化剂表现出相对最佳催化活性。 为了进一步明确催化剂酸碱度的作用并由此研制丙酮酸甲酯合成的高效催化剂,本文制备了不同Ca/P比即具有一定酸碱度差异的...To develop an efficient process for the synthesis of methyl pyruvate from biomass-derived acetol, this dissertation has focused on the study of the effect of acid-base nature on the catalytic performances of supported Au catalyst and the reaction mechanisms involved. Au-based catalysts using different supports were investigated for the oxidative esterification of acetol to methyl pyruvate. The re...学位:理学硕士院系专业:化学化工学院_物理化学学号:2052014115162
An Empirical Test of the Pecking Order Theory
学位:工商管理硕士院系专业:管理学院工商管理教育中心_工商管理硕士(MBA)学号:19981509
Simultaneous determination of 19 phthalate esters in cosmetics using gas chromatography-mass spectrometry
建立了同时测定化妆品中19种邻苯二甲酸酯的气相色谱-质谱(gC-MS)方法。样品经二氯甲烷超声提取后,用硅胶-中性氧化铝(2∶3,M/M)混合填料固相小柱保留、乙酸乙酯-正己烷(8∶2,V/V)洗脱等步骤净化后,采用gC-MS对19种目标物进行定性、定量分析。采用保留时间与特征离子丰度比共同进行定性分析,减少了复杂样品基质中的干扰。在优化的实验条件及0.1、0.5、2.0μg/g的添加水平下,平均加标回收率为72.2%~110.9%,其中加标水平为0.1μg/g的相对标准偏差(rSd,n=6)小于10.3%;方法检出限(以3倍标准偏差计)为0.006 5μg/g(邻苯二甲酸二异戊酯)~0.062μg/g(邻苯二甲酸二异丁酯)之间。应用该方法检测了6种化妆品中19种PAES的含量。该方法可推广用于多种类型化妆品中PAES的测定。A method was developed for the simultaneous determination of 19 phthalate esters(PAEs) at trace level in cosmetics by solid phase extraction(SPE) purification and gas chromatography-mass spectrometry(GC-MS) detection.The PAEs were extracted from cosmetic samples by dichloromethane with ultrasonic-assisted technique,purified by an SPE column packed with silica gel and neutral alumina(2∶ 3,m / m) with the elution of 20 mL of mixed solvent of ethyl acetate-hexane(8∶ 2,v / v).Qualitative and quantitative analysis were carried out by GC-MS in full scan and selected ion monitoring modes.The retention time of quantitative ions and the abundance ratio of characteristic ions were applied to rapidly and accurately identify each analyte so as to prevent the occurring of possible mistakes from complex matrix intervention.Under optimized conditions,the average recoveries for a shampoo sample spiked with the standards at 0.1,0.5,2.0 μg / g were in the range of 72.2% and 110.9%,and the relative standard deviations(RSDs) for the 19 PAEs were less than 10.3%(n = 6) at the spiked level of 0.1 μg / g.The limits of detection(LODs,as 3 times of standard deviation) were between 0.006 5 μg / g(for diisopentyl phthalate) and 0.062 μg / g(for diisobutyl phthalate).The method was successfully applied to the determination of the PAEs in 6 types of cosmetics.It is expected to promote the determination of the PAEs in other cosmetics with different matrices.福建省食品药品监督管理局和福建远东技术服务有限公司委托项
Fe@Fe2O3/石墨烯复合材料的制备与电化学性能研究
采用水热反应和高温固相反应方法合成了Fe@Fe2O3/石墨烯复合材料。运用扫描电子显微镜(SEM)、X射线衍射(XRD)、光电子能谱仪(XPS)和透射电镜(TEM)对复合材料进行了物理表征。结果表明,..
化学氧碘激光器的化学效率以及碘原子多次参与激光作用的现象及其理论分析
通过对COIL各系统评价参数的分析,得到了化学效率依赖于O_2(~1△_g)百分含量的上限表达式,并通过对不同工作条件下亚音速运转的COIL实验数据的综合分析,得到了化学效率η_c的经验公式.进一步通过作为激活介质的激发态碘原子I~*的能量转化效率的定义,首次证明了在COIL中,碘原子多次参与激光作用的现象,并对此作了初步的理论分析