硅钨钼酸掺杂聚苯胺催化合成环己酮乙二醇缩酮

采用浸渍法制备了硅钨钼酸掺杂聚苯胺催化剂.通过环己酮和乙二醇为原料合成环己酮乙二醇缩酮,探讨了硅钨钼酸掺杂聚苯胺催化剂对缩酮反应的催化活性,较系统地研究了原料量比,催化剂用量,反应时间诸因素对产品收率的影响.实验表明硅钨钼酸掺杂聚苯胺是合成环己酮乙二醇缩酮的良好催化剂,在n(环己酮)n(乙二醇)=12.0,催化剂用量为反应物料总质量的1.0%,环己烷为带水剂,反应时间1.0 h的优化条件下,环己酮乙二醇缩酮的收率可达79.2%.     

有机铜催化剂催化合成三乙氧基硅烷

传统的直接法合成三乙氧基硅烷多以卤化铜为催化剂,存在产品卤素含量高,反应过程中产物易水解的问题.本文以乙酸铜和自制双二乙基磷酸铜为催化剂,对硅粉与催化剂的混合体(触体)进行微波活化处理,研究了活性触体和乙醇进行反应合成三乙氧基硅烷的工艺影响因素,主要考察了微波功率、微波处理时间、反应温度、促进剂及搅拌速度等因素对三乙氧基硅烷的选择性和硅粉转化率的影响.通过对两种有机铜催化剂的对比研究发现,双二乙基磷酸铜的催化效果较好.微波处理触体[m(Si):m(双二乙基磷酸铜)=10∶1],以氟化铵和噻吩为双重促进剂,得到三乙氧基硅烷的选择性达到99.3%,硅粉转化率为41%.     

高选择性催化合成乙烯基三乙氧基硅烷

研究了5A分子筛固载铂催化剂的制备,并对它催化乙炔与三乙氧基硅烷硅氢加成反应的催化效果进行了探索.另外还考察了原料配比、催化剂铂含量、反应温度、乙炔流量等因素对目标产物收率的影响.     

含氟缩水甘油醚的合成及表征

采用十二氟庚醇通过醚化-闭环的两步法合成了十二氟庚基缩水甘油醚,考察了反应时间以及催化剂用量、加碱量对产物收率的影响,通过FTIR及13C-NMR表征了合成产物.结果表明,低温长时间的醚化反应有利于提高产物收率,碱用量的摩尔份敷为醇的1.2倍时,产物有较高的收率,达到86%.     

三氟丙醛的合成

以三氟丙烯基甲醚和正戊酸为原料,合成了三氟丙醛.考察了反应温度、物料配比、催化剂用量及反应时间对三氟丙醛收率的影响.在单因素实验基础上,进行了正交试验,得到了较佳反应条件,温度80℃,正戊酸:三氟丙烯基甲醚为1.3,催化剂用量2.3%,反应时间9h,此条件下三氟丙醛的收率为91.47%.     

3-氯丙基三甲氧基硅烷合成新方法的研究

为提高产率、降低成本,以3-氯丙烯和三甲氧基硅烷为原料、水合三氯化钌为催化剂进行3-氯丙基三甲氧基硅烷的一步合成反应,研究了反应温度、催化剂浓度、原料的加料方式、反应时间、原料的配比对产物收率的影响.结果表明,最佳的反应条件为反应温度80℃、钌催化剂质量分数63 μg/g、3-氯丙烯向三甲氧基硅烷中滴加方式、三甲氧基硅...     

光敏性有机硅丙烯酸酯的合成及表征

以含氢硅油和三缩丙二醇二丙烯酸酯(TPGDA)为原材料,氯铂酸为催化剂,采用硅氢加成方法直接合成了光敏性有机硅丙烯酸酯.探讨了反应时间、反应温度、溶剂、催化剂用量以及阻聚剂用量等因素对反应的影响,对反应产物进行了红外光谱分析,对产物的光固化性能进行了研究.     

甲基(γ-氯丙基)二氯硅烷的合成研究

以磷配体对氯铂酸硅氢加成催化剂进行改性,以γ-氯丙烯和甲基二氯氢硅为原料合成甲基(γ-氯丙基)二氯硅烷.探讨了该催化剂对硅氢加成反应的催化活性,较系统地研究了催化剂用量、配体与氯铂酸摩尔比、温度控制等因素对产品收率的影响.实验表明:氯铂酸-磷配体催化剂是合成甲基(γ-氯丙基)二氯硅烷的良好催化剂,在n(氯铂酸):n(磷配体)=1:3,催化剂用量为反应物料总摩尔数的1.5×10-5,一次投料方式,反应时间3.0h的优化条件下,甲基(γ-氯丙基)二氯硅烷的产率可达77.9%.     

环氧(甲基)丙烯酸酯树脂的制备及应用研究

用正交设计法研究了(甲基)丙烯酸对环氧树脂的改性反应，探讨了反应温度、催化剂和阻聚剂用量对产物的影响。用红外光谱(FT-IR)对产物的结构和性能进行了表征，同时进行了应用实验。     

硅粉形貌对人工合成高纯碳化硅粉料的影响

合成了适于半绝缘碳化硅单晶生长的高纯度SiC粉料.实验发现,不同的硅粉形状、粒度以及合成温度、时间都对合成产物的形貌、组成和产率有影响.合成产物的形貌通过扫描电子显微镜(SEM)观察,结构通过粉末衍射法(XRD)测定.结果表明,合成产率与Si粉的表面积有十分重要的关系,表面积越大,合成产率越高.合成温度和时间则决定了合成产物中岐睸iC和猹睸iC的比例.辉光放电质谱(GDMS)测量了合成产物的杂质含量,表明合成产物符合半绝缘SiC单晶的生长要求.     

正交法探讨均相碱催化制备生物柴油的优化条件

以菜籽油为原料,甲醇钠为催化剂,二异丙醚为共溶剂,通过酯交换法制取生物柴油,并考察了醇油摩尔比、催化剂用量、共溶剂用量、反应时间和温度对生物柴油产率的影响.通过正交试验得出菜籽油与甲醇酯交换反应的最优条件为:醇油比为6:1,甲醇钠催化剂用量为油重的1.2%,共溶剂与油的摩尔比为1.2 :1,反应温度60℃,反应时间80min,低速120r/min搅拌强度下,转化率达到96.45%.制得的生物柴油各理化指标均符合美国和德国生物柴油测试标准.     

二(3,5-二硝基苯甲酸)二甘醇酯的合成研究

文章以3,5-二硝基苯甲酸和二甘醇为原料,在钛酸四丁酯的催化条件下,合成了二(3,5-二硝基苯甲酸)二甘醇酯.正交试验结果显示,当酸醇的量比为2.05,催化剂的量为3,5-二硝基苯甲酸的0.95%,反应时间为100 min,带水剂的量占3,5-二硝基苯甲酸的35.5%,收率较高(90%),产物结果经IR、MS、H1NMR表征证实为目标化合物.     

掺杂镧的固体碱MgO/SBA-15催化大豆油制备生物柴油

采用浸渍法制备了掺杂镧的固体碱MgO/SBA-15催化剂,将其用于大豆油酯交换制备生物柴油的反应。XRD表征结果显示,活性组分在载体SiO2骨架中高度分散。考察了不同镧镁物质的量比、焙烧温度和催化剂用量等因素对催化剂性能的影响,发现镧的引入有利于催化剂与反应物的接触,从而提高催化剂的活性;镧和镁物质的量之比为0.5∶1,催化剂焙烧温度700℃,焙烧时间3h,催化剂质量分数为3%,反应时间3h时,生物柴油的产率达到95%以上。     

Synthesis of amorphous silicon carbide nanoparticles in a low temperature low pressure plasma reactor

Commercial scale production of silicon carbide (SiC) nanoparticles smaller than 10?nm remains a significant challenge. In this paper, a microwave plasma reactor and appropriate reaction conditions have been developed for the synthesis of amorphous SiC nanoparticles. This continuous gas phase process is amenable to large scale production use and utilizes the decomposition of tetramethylsilane (TMS) for both the silicon and the carbon source. The influence of synthesis parameters on the product characteristics was investigated. The as-prepared SiC particles with sizes between 4 and 6?nm were obtained from the TMS precursor in a plasma operated at low temperature and low precursor partial pressure (0.001-0.02?Torr) using argon as the carrier gas (3?Torr). The carbon:silicon ratio was tuned by the addition of hydrogen and characterized by x-ray photoelectron spectroscopy. The reaction mechanism of SiC nanoparticle formation in the microwave plasma was investigated by mass spectroscopy of the gaseous products.     

ZnO impregnated MgAl(O) catalyst with improved properties for biodiesel production: The influence of synthesis method on stability and reusability

ABSTRACT

A magnesium-aluminum layered double hydroxide was synthesized with co-precipitation method and zinc salt was impregnated on it. The final product was calcined and used as a catalyst in the transesterification reaction to produce biodiesel from waste cooking oil. Both MgAl hydrotalcite and Zn impregnated compound (Zn/MgAl(O)) were characterized using X-Ray Diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS) techniques. High surface area and nanometric pore size of Zn/MgAl(O) was determined using Bruneure-Emmett-Teller N₂ physisorption technique. Another fully co-precipitated ZnMgAl mixed oxide was synthesized by and compared with Zn impregnated product in the transesterification reaction. The reactions were performed at 65°C using 9:1 methanol to oil ratio for 3?h. The biodiesel yields were measured by gas chromatography (GC). Leaching amounts of surface active components of as-synthesized mixed metal oxides were determined by EDS and ICP analysis of used catalyst. Zn impregnated catalyst showed 78.45% conversion of the fatty acid to methyl esters and just 1.16% leaching of Zn was observed, that is much lower than the diminishing in the co-precipitated compound. Finally, the reaction and leaching proofs and the effect of synthesis method on the firmness of catalyst were discussed.     

Electrocatalytic activity of surface atoms of platinum supported on silicon

The influence of a carrier matrix on the electrocatalytic activity of platinum nanoparticles with respect to the reaction of methanol oxidation in an acid medium has been studied using a cyclic voltammetry technique. Platinum nanoparticles were formed on the surface of carbon black (commercial E-TEK type catalyst), p-type silicon single-crystals wafers with different resistivities, and mesoporous silicon. It is established that the activity of surface Pt atoms is higher for platinum nanoparticles supported on silicon than on carbon black. An increase in the resistivity of silicon favors growth in the catalytic activity of platinum. The most pronounced carrier effect is produced by the mesoporous silicon matrix.     

Preparation of Monodisperse Spherical SiO_2 by Microwave Hydrothermal Method and Kinetics of Dehydrated Hydroxyl

Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (...     

Modification of FAU zeolite as an active heterogeneous catalyst for biodiesel production and theoretical considerations for kinetic modeling

In this work, a high purity FAU-type zeolite catalyst was prepared from shale rock and modified as a heterogeneous efficient catalyst for biodiesel production from sunflower oil. The characterization properties for both of the prepared catalysts were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), Brunauer–Emmett–Teller (BET), and Fourier-transform infrared spectroscopy (FTIR). The incipient wetness impregnation method was adopted for loading the catalyst with three base precursors: NaOH, KOH, and Ca(OH)3. Different factors affecting transesterification reaction onto modified Na-K-Ca-FAU zeolite were investigated such as; temperature (35, 45, 55, and 65 °C), catalyst concentrations (2, 3,4, 5, and 6 wt%) and the molar ratio of methanol to sunflower oil (3:1, 6:1, 9:1 and 12:1). The optimum conditions of transesterification reactions were obtained for reaction time (4 h) and agitation rate (700 rpm) in a batch reactor at 65 °C reaction temperature, 5% catalyst concentration, and a 9:1 M ratio of methanol to oil. The experimental results showed that the conversion of triglyceride in sunflower oil to fatty acid methyl ester (FIME) increased from 48.62 to 91.6% when the FAU zeolite was loaded with 15 wt% of the three bases. The properties of the produced biodiesel were evaluated within the standard performance ASTM D-6751. This study shows that the three base precursors (i.e., NaOH, KOH, and Ca(OH)3) were successfully loaded onto support FAU zeolite and functioned as excellent catalysts for biodiesel production. Theoretical considerations for kinetic modeling in the heterogeneous transesterification reaction were investigated using MATLAB programming. The experimental and theoretical considerations for kinetic modeling were fitted well.     

MPCVD法在碳纤维上制备碳纳米管

利用微波等离子体化学气相沉积（MPCVD）法在碳纤维上制备了碳纳米管,并在此基础上系统地研究了微波功率、反应时间、催化剂前驱体的吸附时间以及吸附浓度对碳纳米管生长的影响.采用扫描电子显微镜（SEM）对样品的表面形貌进行表征.结果表明,微波功率、反应时间对碳纳米管的形貌有很大影响,此外,随着吸附时间的增加,碳纳米管的生长速度快且产量高;吸附浓度很大时,碳纤维表面上产生了大量的无定形碳和石墨,严重影响了碳纳米管的生长质量.