Cu基催化剂上的酸中心研究

催化剂表面的酸中心常常是反应发生的活性部位,直接影响催化剂的催化活性,红外光谱法由于可以有效区分B酸和L酸,而被广泛应用来研究固体材料表面酸性。利用原位吡啶-FT-IR表征方法,对吸附吡啶的还原后纯Cu、Cu-Cr和Cu-Cr-Zr 5%催化剂样品分别进行程序升温研究,研究结果表明:纯Cu催化剂表面具有L酸中心,没有B酸中心;Cu-Cr和Cu-Cr-Zr 5%催化剂表面都具有L酸中心,同时因为Cr的加入,引入了B酸位,但这些B酸中心的数量相比L酸来说相对较少,强度较弱。     

Cu/ZnO/Al_2O_3甲醇合成催化剂AsH_3中毒热力学分析

利用HSC热力学软件对Cu/Zn O/Al_2O_3甲醇合成催化剂As H_3中毒热力学进行了计算。分析了在150°C~300°C的合成温度下催化剂可能发生的化学反应,并比较各自发反应的化学平衡常数。结果表明:合成原料气组分(CO、H_2O、N_2、O_2)能引起催化剂砷中毒。其中,O_2对催化剂砷中毒的影响最大,参与反应的热力学竞争力最强,产物Cu_3As、As_2O_5、As_2O_3和Cu_3(AsO_4)_2可能导致催化剂失活。为应对砷中毒,应在合成反应之前深度净化合成气。     

不同表面活性剂对尿酸电化学行为的影响

在银掺杂聚L-苯丙胺酸修饰电极上,以人体代谢产物尿酸为探针,研究了不同表面活性剂(十六烷基三甲基溴化铵(CTMAB)、十二烷基硫酸钠(SDS)和聚乙二醇单辛基苯基醚(Triton X-100))存在下对尿酸电化学行为的影响。结果表明,三种不同类型表面活性剂对尿酸的电化学行为均有影响,不同表面活性剂存在下,尿酸在修饰电极上氧化电位变化不大,氧化电流均有所降低,在研究的三种不同类型表面活性剂中,对峰电流的影响最大的是CTMAB、最小的是SDS。     

CoMo/Al_2O_3催化剂上FCC汽油加氢脱硫活性研究

采用等体积浸渍法合成了Co/Mo/Al_2O_3催化剂,采用N_2吸附-脱附、扫描电镜(SEM)对催化剂进行了表征,针对CoMo/Al_2O_3催化剂,改变温度和空速进行催化裂化(FCC)汽油加氢脱硫评价试验,考察了FCC汽油中单环噻吩类和苯并噻吩类硫化物的脱硫率,发现了加氢脱硫活性与硫化物的电子云密度相关联的规律:硫化物的电子云密度越高,则加氢脱硫转化率越高,硫化物越容易脱除。采用Gaussian 03程序中的密度泛函理论(DFT)方法,在B3LYP/6-31G水平上对噻吩及其衍生物的分子结构进行了全优化计算,获得了噻吩及其衍生物中双键键级及硫原子的电负性,验证了试验中硫化物加氢脱硫和其电子云密度相关联的规律。     

表面活性剂和有机小分子对固体支撑双层膜的影响

利用表面等离子体共振(surface plasmon resonance,SPR)和交流阻抗技术,研究了表面活性剂和有机小分子对两种固体支撑双层膜的影响.结果表明其破坏磷脂膜的机理不同,且这两种固体支撑双层膜在抗化学破坏能力方面具有细微的差别.     

浓H_2SO_4改性活性炭催化甲苯与氯化苄的苄基化反应

以活性炭负载浓硫酸作为固体催化剂,以甲苯与氯化苄为原料进行合成反应,研究了反应温度、反应时间、原料配比和催化剂用量对反应的影响,确定了最佳工艺条件,即月(甲苯):n(氯化苄)=3:1,反应温度100℃,反应时间12 h,催化剂用量7.9%(相对于氯化苄),邻苄基甲苯产率为31.1%:n(甲苯):n(氯化苄)=3:1,反应温度90℃,反应时间12 h,催化剂用量10.5%相对于绿化苄),对苄基甲苯产率为41.8%;n(甲苯):n(氯化苄)=3:1,反应温度90℃,反应时间7h,催化剂用量7.9%(相对于绿化苄),间苄基甲苯产率为3.4%。     

用离子选择电极测定硝盐包覆层的痕量阴离子表面活性剂

工业上一般生产的硝酸钠和亚硝酸钠会产生结块现象,影响使用质量。若在结晶母液槽中加入一定浓度的阴离子表面活性剂十二烷基苯磺酸钠(DBS),在晶粒界面能生成包覆层,可防止结块。如何控制监测结晶槽中痕量 DBS 的浓度,将是生产过程的关键。由于大量的 NO_3~-或 NO_2~-离子的存在,对测定痕量阴离子表面活性剂的次甲基兰比色法和电位滴定法带来干扰。本文用液膜型阴离子洗涤剂电极(AD 电极),研究了在0.01～0.20MNaNO_3或 NaNO_2电介质溶液中 DBS 的临界胶束浓度(CMC)的变化规律和电极的线性响应范围,建立了直接电位法测定硝盐包覆层的痕量阴离子表面活性剂。当 DBS 浓度为     

浆态床法合成二甲醚的模拟研究

对于直接以合成气作为原料,使用Cu-Zn-Al和γ-Al2O3构成的双重催化剂、采用浆态床法合成二甲醚的反应体系,使用全混流反应器模型结合化学反应动力学进行模拟。组分方程使用超松弛迭代方法并结合C 编程进行求解,编制了计算机程序。通过模拟计算,讨论了压力、温度、空速、催化剂配比、反应气中不同氢碳比以及CO2含量对反应收率、DME选择性的影响,并讨论了在不同氢碳比下对CO转化率和CO与H2总转化率的影响,从而寻找合适的反应条件,为工业化生产提供参考。     

铁基催化剂上费托合成本征动力学研究

采用共沉淀方法制备了低温沉淀铁基催化剂,并在管式固定床反应器中对其动力学性能进行了考察。假定H2在催化剂表面不同的吸附形式,推导得到了基于H2解离吸附与非解离吸附的CO消耗本征动力学模型。动力学实验数据拟合以及通用全局算法优化结果表明,基于H2以解离态吸附在催化剂表面并参与费托合成反应所推导得到的动力学方程更加符合实验结果。数据拟合及统计学分析表明,在温度230℃~260℃,压力2.0 MPa~4.0 MPa,空速(2000~3000)h-1,H2/CO摩尔比0.96~2.08的操作条件范围内,在该低温沉淀铁基催化剂上的费托合成反应活化能为81.42 k J/mol,在文献所报道范围内。     

金纳米颗粒制备及其光学特性研究

采用晶种生长法通过改变晶种对生长溶液的体积比例、引入离子合成了棒状和星形金纳米颗粒.首先用NaBH4作为还原剂制得小粒径球形金纳米颗粒作为晶种溶液,生长溶液中引入AgNO3为辅助试剂、溴化十六烷三甲基铵(CTAB)为表面活性剂来引导合成形貌不同的颗粒.对制备的球状、棒状和星状金纳米颗粒进行了紫外-可见光谱测试和表面增强...     

聚甘油脂肪酸酯QSPR的研究

采用量子化学MOPAC-AM1和单点能方法计算聚甘油脂肪酸酯的分子结构参数,然后用逐步线性回归方法建立聚甘油脂肪酸酯HLB值的定量结构性质(QSPR)模型,所得的预测模型中包含4个参数[单位质量分子所含氧原子数Xo、生成热fHm、电子能Ee和水合能Eh,预测值及外部检验的复相关系数(R2)和标准偏差(SD)分别为0.9553、0.73722和0.9678、6.34426。结果表明,量子化学方法计算简单,对聚甘油脂肪酸酯结构的表征能力较强,所建定量结构性质模型具有能较好的预测能力和较强的稳健性,并在一定程度上阐明了聚甘油脂肪酸酯HLB值与其分子结构之间的关系。     

Estimation of surface tension of methyl esters biodiesels using computational intelligence technique

Due to environmental benefits, methyl esters biodiesel got a considerable attention as a viable substitute to petroleum-based diesel. Surface tension plays significant role in atomization of this biodiesel since it controls the combustion process inside the engine through fuel–air mixing. Experimental determination of the surface tension of biodiesel is expensive and time consuming which limits its application as substitute for petroleum-based diesel. This is because proper choice of any methyl esters for diesel engine applications depend on the value of surface tension as high value of surface tension brings about difficulty in droplet formation. This work employs computational intelligence technique on the platform of sensitivity based linear learning method (SBLLM) to develop methyl esters surface tension estimator (MESTE) which estimates surface tension of methyl esters biodiesel with high degree of accuracy. Surface tensions of eight different classes of methyl esters were estimated at different temperatures by training and testing of neural network using SBLLM. The estimated surface tensions were compared with experimental results as well as surface tension obtained from Parachor model and Goldhammer model. The outstanding performance of the developed MESTE suggests its potential in estimating surface tension of methyl esters biodiesel for enhancing the atomization in biodiesels engine applications.     

Theoretical Study on Free Fatty Acid Elimination Mechanism for Waste Cooking Oils to Biodiesel over Acid Catalyst

A theoretical investigation on the esterification mechanism of free fatty acid (FFA) in waste cooking oils (WCOs) has been carried out using DMol³ module based on the density functional theory (DFT). Three potential pathways of FFA esterification reaction are designed to achieve the formation of fatty acid methyl ester (FAME), and calculated results show that the energy barrier can be efficiently reduced from 88.597 kcal/mol to 15.318 kcal/mol by acid catalyst. The molar enthalpy changes (Δ_rH_m°) of designed pathways are negative, indicating that FFA esterification reaction is an exothermic process. The obtained favorable energy pathway is: H⁺ firstly activates FFA, then the intermediate combines with methanol to form a tetrahedral structure, and finally, producing FAME after removing a water molecule. The rate-determining step is the combination of the activated FFA with methanol, and the activation energy is about 11.513 kcal/mol at 298.15 K. Our results should provide basic and reliable theoretical data for further understanding the elimination mechanism of FFA over acid catalyst in the conversion of WCOs to biodiesel products.     

脂肪酯结构与折光指数之间定量关系的探讨

根据分子拓扑学原理，用距离矩阵描述分子结构，用染色因子标识分子中的原子，发展了一种结构性能关系研究的新方法．据此探讨了脂肪酯结构与折光指数的关系、提出了预测折光指数的定量关系式．对１４９种脂肪酯的计算结果表明，折光指数预测值与实验值的一致性令人满意，平均误差０．２１６％．     

催化反应转化率与催化剂组分含量的关系式

针对三种不同物料连续流动催化反应系统:(1)MoVTeNbO/SiO2用于丙烷选择氧化制丙烯醛反应;(2)KMoNi/SiO2用于高硫合成气制甲硫醇反应;(3)MoNiP/Al2O3用于噻吩加氢脱硫反应.在各自的固定反应条件下,研究催化反应转化率与催化剂组分含量的关系,提出半经验表达式:xA=1-exp[-G(wi)],G(wi)=6∑l=0n∑j=1j≠in∑i=1 bijlwiwlj.利用此式拟合上述3个催化反应系统的实验数据,平均相对偏差分别为1.97%,1.54%和1.42%,拟合精度较高,证明所提出的关系式是合理的,而且颇有普适性,可用于优化设计催化剂组分的含量.     

Production of Candida antarctica lipase B gene open reading frame using automated PCR gene assembly protocol on robotic workcell and expression in an ethanologenic yeast for use as resin-bound biocatalyst in biodiesel production

A synthetic Candida antarctica lipase B (CALB) gene open reading frame (ORF) for expression in yeast was constructed, and the lycotoxin-1 (Lyt-1) C3 variant gene ORF, potentially to improve the availability of the active enzyme at the surface of the yeast cell, was added in frame with the CALB ORF using an automated PCR assembly and DNA purification protocol on an integrated robotic workcell. Saccharomyces cerevisiae strains expressing CALB protein or CALB Lyt-1 fusion protein were first grown on 2% (w/v) glucose, producing 9.3 g/L ethanol during fermentation. The carbon source was switched to galactose for GAL1-driven expression, and the CALB and CALB Lyt-1 enzymes expressed were tested for fatty acid ethyl ester (biodiesel) production. The synthetic enzymes catalyzed the formation of fatty acid ethyl esters from ethanol and either corn or soybean oil. It was further demonstrated that a one-step-charging resin, specifically selected for binding to lipase, was capable of covalent attachment of the CALB Lyt-1 enzyme, and that the resin-bound enzyme catalyzed the production of biodiesel. High-level expression of lipase in an ethanologenic yeast strain has the potential to increase the profitability of an integrated biorefinery by combining bioethanol production with coproduction of a low-cost biocatalyst that converts corn oil to biodiesel.     

氧化钙固硫反应动力学中的计算机模拟碱金属离子效应

研究了用催化剂提高CaO固硫率的可行性及其催化剂对固硫反应动力学的影响。用热天平研究了在CaO中添加不同催化剂后的固硫反应的进程,并用等效粒子模型来模拟和处理实验数据,计算了固硫反应动力学参数。结果表明,CaO固硫反应初期为表面化学反应控制阶段,后期转为产物层扩散控制阶段。碱金属的盐类催化剂均能使固硫反应前期的化学反应控制阶段的反应活化能E_α下降。E_α的大小按催化剂中Li~ 、Na~ 、K ~ 、Cs~ 离子半径增大的顺序依次递减;而碱金属盐类催化剂使固硫反应后期的产物层扩散控制阶段的反应活化能E_P不同程度地增加。     

草酸二甲酯加氢制乙醇酸甲酯产品分离方案模拟比较

草酸二甲酯(DMO)加氢制乙醇酸甲酯(MG)是延长煤化工产品链的一条重要技术路径。由于乙醇酸甲酯(MG)的主要用途是水解制备乙醇酸(GA),工艺上可以有2种分离方案。方案1为先精馏提纯MG,然后MG水解制备GA。方案2则为DMO加氢反应混合物直接先去水解,然后再进行产物分离获得GA。本文分别对2种分离工艺进行了模拟,并对精馏塔级数,回流比,过程能耗等方面进行了比较,结果表明方案1能耗更低,且产品分离塔所需理论板数较少,所以DMO加氢制MG反应产物采取先精馏分离MG后水解生产GA的工艺比较合理。     

Plant-wide design and control of acetic acid dehydration system via heterogeneous azeotropic distillation and divided wall distillation

Energy-saving plant-wide design and plant-wide control of an acetic acid dehydration system with the feed containing methyl acetate and p-xylene are investigated in the study. A heterogeneous azeotropic distillation using isobutyl acetate as an entrainer is designed to obtain high-purity acetic acid at the column bottom and to keep a small acetic acid loss through the top aqueous draw. The accumulation of p-xylene in the column is avoided by adding a side product stream. The mixture in the aqueous phase of decanter, containing mostly water, methyl acetate, and isobutyl acetate is separated using a divided wall distillation column. The whole acetic acid dehydration system includes a heterogeneous azeotropic distillation column and a divided wall distillation column.The control strategies using temperature loops are proposed for this acetic acid dehydration system. For the heterogeneous azeotropic distillation column, the requirements for acetic acid compositions in both the aqueous phase of the decanter and the column bottom can be satisfied by designing entrainer inventory temperature control and cascade temperature control simultaneously. The stages of controlled temperatures are chosen by singular value decomposition and closed-loop analysis methods based on the criteria of minimum entrainer makeup. For the divided wall distillation column, steady-state analysis methods are used for the selection of proper controlled and manipulated variables and the determination of their pairings. Dynamic simulation results demonstrate that the proposed plant-wide control strategy can maintain product purities and reject external disturbances in feed flow and composition changes as well as internal disturbances such as changes in liquid and vapor splits.     

Theoretical investigation of the selective dehydration and dehydrogenation of ethanol catalyzed by small molecules

Catalytic dehydration and dehydrogenation reactions of ethanol have been investigated systematically using the ab initio quantum chemistry methods The catalysts include water, hydrogen peroxide, formic acid, phosphoric acid, hydrogen fluoride, ammonia, and ethanol itself. Moreover, a few clusters of water and ethanol were considered to simulate the catalytic mechanisms in supercritical water and supercritical ethanol. The barriers for both dehydration and dehydrogenation can be reduced significantly in the presence of the catalysts. It is revealed that the selectivity of the catalytic dehydration and dehydrogenation depends on the acidity and basicity of the catalysts and the sizes of the clusters. The acidic catalyst prefers dehydration while the basic catalysts tend to promote dehydrogenation more effectively. The calculated water-dimer catalysis mechanism supports the experimental results of the selective oxidation of ethanol in the supercritical water. It is suggested that the solvent- and catalyst-free self-oxidation of the supercritical ethanol could be an important mechanism for the selective dehydrogenation of ethanol on the theoretical point of view.