Cu-Zn-Al催化剂上糠醛气相加氢制糠醇的研究

Mn改性Cu Zn Al催化剂是糠醛气相加氢制糠醇的有效催化剂 ,在较温和的条件下 (氢醛比 :9;糠醛液体空速 :1 0h-1;反应温度 :130℃ ) ,糠醛转化率为 99 8% ,糠醇选择性 97 7%。K助剂的浸入可进一步提高糠醇的选择性。工业侧线运行结果表明 ,Cu Zn Al催化剂有较好的活性     

Characteristics of hemicelluloses obtained from sweet sorghum based on successive extractions

Hemicelluloses were successively extracted from sweet sorghum by hot water, dioxane, DMSO, and different concentrations of NaOH between 0.5% and 6.0%. The yields of the seven fractions together accounted for 88.6% of the original hemicelluloses. The obtained hemicellulosic subfractions were comprehensively investigated by both destructive methods such as alkaline nitrobenzene oxidation and acid hydrolysis and nondestructive techniques such as gel permeation chromatography, Fourier‐transform infrared, ¹³C‐nuclear magnetic resonance, and 2D‐heteronuclear singular quantum correlation. Sugar composition studies showed that the water‐soluble polysaccharides consisted mainly of glucose, while xylose, arabinose, and glucuronic acid were the major sugars in other hemicellulosic fractions. It was found that the hemicelluloses from sweet sorghum were l‐ arabino‐(4‐O‐methyl‐d‐ glucurono)‐xylans. Comparison with the hemicellulosic fractions dissolved by the alkali treatment, the hemicellulosic fraction extracted by DMSO had lower molecular weight. In addition, it was also found that the hemicelluloses prepared by dioxane and DMSO were more branched since that they had higher nonxylose/xylose ratios than those extracted by the alkali treatment, which were more linear and contained higher amounts xylose. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42790.     

五种金属离子对Rhodosporidium toruloides Y2产油的影响

研究Fe3+、Cu2+、Mg2+、Ca2+和Zn2+等五种金属离子对Rhodosporidium toruloides Y2产油的影响;采用单因素实验设计法,生物量测定采用重量法,油脂含量测定采用氯仿甲醇法,葡萄糖浓度采用DNS法测定;发酵培养基中添加适当浓度的Fe3+(10 mg/L)、Cu2+(10 mg/L)、Mg2+(0.5 g/L)、Ca2+(1 g/L)和Zn2+(5 mg/L)可提高酵母生物量和油脂含量。其中Cu2+、Ca2+和Zn2+添加对酵母生长和产油的影响较为显著,生物量得率达到0.35 g/g以上,油脂得率达0.20 g/g,分别比空白组增加了16.7%和33.3%;本研究通过优化金属离子浓度提高了R.toruloides Y2生物量和油脂积累效率,为提高微生物油脂生产效率提供了有用的参考。     

固体废物中多环芳烃萃取的前处理技术及测定方法综述

多环芳烃(PAHs)是环境中广泛存在的一类污染物,其存在于水体、大气及土壤介质中,具有种类多及对环境危害大的特点。近年来,PAHs逐渐成为人们研究的重点,虽然国内外已有PAHs的监测技术的分析标准,但是其提取与测定是一个系统的过程,且不断发展和优化。比较了近年来固体废物(如土壤、污泥等)中PAHs的分析过程中所涉及的萃取、净化及测定方法,总结了各种分析方法的优缺点,介绍了一些新的分析技术。     

Exploring suitable ZSM-5/MCM-41 zeolites for catalytic cracking of n-dodecane: Effect of initial particle size and Si/Al ratio

In this study, various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5. The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied. The results of XRD, TEM N₂-adsorption-desorption, NH₃-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals, and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5. Catalytic cracking of n-dodecane (550 ℃, 4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance, with the improvement higher than 87% in the catalytic activities and 21% in the deactivation rate compared with untreated zeolites. This could be ascribed to their suitable pore structure, which enhanced the diffusion of reactant molecules in pores of catalysts.     

微波法促进ZnO在ABS表面附着及影响因素的研究

通过采用微波方法使氧化锌(Zn O)在苯乙烯-丁二烯-丙烯腈共聚物(ABS)上进行附着,并使用XRD和扫描电镜手段观察Zn O微粒形态,使用附着质量与亲水性表征不同微波时间,不同预聚物浓度及不同粗糙度的ABS表面对Zn O生成的影响。结果表明:使用微波方法可以快速(2 min)有效地使Zn O晶体附着在塑料表面。     

钦州湾海域夜光藻赤潮发生区水文气象因子变化研究

通过跟踪监测2011年4月发生在钦州湾海域的夜光藻赤潮,分析了环境因子变化情况与赤潮发生区域的营养状况。结果表明:适宜的水文气象条件和丰富的营养盐为夜光藻赤潮的爆发及维持提供了基础。其中高氮磷比成为限制夜光藻生长的重要因素。     

供给侧视角下仪器分析课程分层分类教学研究

在供给侧视角下,通过优化分类仪器分析教学大纲,实施分层教学及考核方法,改进教学方法及手段,激发学生对仪器分析课程学习的兴趣和积极性,提高仪器分析课堂教学质量,提升学生对课堂关注度,实施因材施教,以满足专业及学生的需求,满足用人单位的需求,提高学生的就业竞争力。     

三元水盐体系冰点和共晶点的测定、相图表达及计算

针对Na⁺//Cl^-,NO₃^--H₂O、Na⁺//Cl^-,SO₄^2--H₂O和Na⁺,K⁺//Cl^--H₂O 3个三元水盐体系,测定了不同组成时溶液的冰点、共晶点以及降温过程的析盐规律,绘制出三元体系温度-组成立体相图。结果表明：三元体系的冰点、共晶点、相关系与组成可用三棱柱表达,3个三元水盐体系在共晶点温度下均无复盐存在,各含有1个两盐与冰的共晶点,3条单盐与冰或盐盐的共晶线,1个冰和两个单盐结晶区;用三元体系温度-组成立体相图能更直观地表达三元水盐体系的结晶区、冰点、共晶点和溶液组成的关系,可以判断溶液降温过程中的盐或冰的析出类型、温度;同时建立了冰点经验公式,应用经验公式和过量吉布斯自由能模型预测三元体系的冰点和共晶点,计算值和实验值吻合良好。