无水AlCl_3作用下EPDM的交联与接枝性能

以无水AlCl3为催化剂,在溶液体系考察了温度、催化剂用量、溶剂品种等因素对乙丙三元橡胶(EPDM)交联与接枝性能的影响。结果显示,无水AlCl3可以引发EPDM间产生交联反应;温度较低时,EPDM交联反应困难,但乙丙三元橡胶与聚苯乙烯(PS)间产生了接枝反应;在苯与二甲苯溶剂中不易形成活性正碳离子;催化剂用量增大,凝胶含量与交联密度增大;PS进入EPDM凝胶网络,使PS相热稳定性提高,玻璃化温度提高。     

双金属催化环氧化物聚合诱导期的研究

用观察反应体系压力变化的方法测定了不同条件下双金属氰化络合催化剂催化环氧丙烷(PO)聚合的诱导期。发现诱导期与催化剂的结构组成、反应温度、体系中水分含量、分子量调节剂和溶剂的种类及用量等因素有关。适当地提高聚合温度,严格控制体系中水分含量,并选择合适的分子量调节剂和加料工艺均能够有效地缩短诱导期。     

新型钼（VI）系配合物催化烯丙醇聚合反应研究

合成出一种新型Mo（Ⅵ）系配合物MoO2Cl2（MePhzPO）2，并用IR、1H-NMR对其结构进行表征。首次报道以MoO2Cl2（MePh2PO）2为催化剂，叔丁基过氧化氢（TBHP）为氧源，催化烯丙醇的直接聚合反应，产物为2，3-环氧-1-丙醇低聚物。此反应体系条件温和，易于控制；IR、1H—NMR及LC-MS的分析结果说明产物为低聚物。考察了单体与催化剂的比例、反应温度、反应时间、溶剂及氧源等对聚合反应及产物分子量的影响：甲苯是该反应的最佳溶剂；以甲苯为溶剂，反应温度80℃，反应时间4h，催化剂／烯丙醇／TBHP（摩尔比）为1／200／200，此时产物分子量可达到666。     

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.     

聚醚改性三硅氧烷的合成

以不饱和聚醚和含氢硅油为原料,氯铂酸作催化剂,异丙醇为溶剂,通过硅氢加成反应合成出聚醚改性三硅氧烷.通过控制反应物配比、反应温度、时间和催化剂用量,研究了反应的较优反应条件:聚醚中的C=C双键与含氢硅油中的Si-H键物质的量之比为1.1:1.0,反应温度75℃,反应时间5.0h,催化剂用量与含氢硅油中Si-H键物质的量之比为5.0×10-5:1.     

甲基辛基二甲氧基硅烷的合成研究

以辛烯和甲基二甲氧基氢硅为反应物,甲苯为溶剂,铂络合物为催化剂,在一定温度下生成甲基辛基二甲氧基硅烷.并讨论了反应温度、反应物的摩尔比、溶剂的用量、反应时间对产率的影响.     

用水热、溶剂热方法制备纳米CdS粒子及其光催化性能

以硫化钠和硫代乙酰胺为硫源,用水热和溶剂热方法制备了不同粒径的纳米硫化镉半导体光催化剂.借助X射线衍射（XRD）,UV-Vis漫反射对CdS催化剂进行了表征.以甲酸水溶液的光催化制氢反应为探针,评价了不同合成方法对催化剂活性的影响;用电化学方法测定了CdS光腐蚀程度.结果表明,反应物、溶剂与温度等都可影响CdS晶型与结晶度,导致其光催化活性差异;CdS光腐蚀性与其晶型有关,并随结晶度的提高显著降低,这说明通过控制合适的条件可制备高活性低腐蚀的CdS.     

新型钼(Ⅵ)系配合物催化烯丙醇聚合反应研究

合成出一种新型M o(Ⅵ)系配合物M oO2C l2(M ePh2PO)2,并用IR、1H-NM R对其结构进行表征。首次报道以M oO2C l2(M ePh2PO)2为催化剂,叔丁基过氧化氢(TBHP)为氧源,催化烯丙醇的直接聚合反应,产物为2,3环-氧-1丙-醇低聚物。此反应体系条件温和,易于控制;IR、1H-NM R及LC-M S的分析结果说明产物为低聚物。考察了单体与催化剂的比例、反应温度、反应时间、溶剂及氧源等对聚合反应及产物分子量的影响:甲苯是该反应的最佳溶剂;以甲苯为溶剂,反应温度80℃,反应时间4 h,催化剂/烯丙醇/TBHP(摩尔比)为1/200/200,此时产物分子量可达到666。     

超支化PNP铬系催化剂的合成及对乙烯齐聚的催化性能

以正己胺为核的1.0G超支化大分子(R6-1.0G)、氯代二苯基膦和CrCl3(THF)3为原料,合成了一种新型的超支化PNP铬系催化剂(R6-Cat)。红外光谱、核磁共振氢谱和紫外光谱证实合成产物的结构与理论结构相符。在合成的基础上,对该催化剂催化乙烯齐聚的性能进行了研究。考察了溶剂种类、反应温度、Al/Cr比、反应压力等条件对该催化剂催化乙烯齐聚性能的影响。结果表明,当以甲苯为溶剂,甲基铝氧烷(MAO)为助催化剂时,该催化剂表现出良好的催化乙烯齐聚性能。随着反应温度和Al/Cr比的增加,催化活性先升高后降低;而催化活性随着反应压力的增加而增大。当反应温度为35℃、Al/Cr比为500、反应压力为1.0 MPa时,催化活性可达2.02×104 g/(mol Cr·h),聚合产物主要是C8以下的低碳烯烃,含量高达92%以上。相同条件下,其催化乙烯齐聚的活性高于与其结构类似但烷基链长度不同的超支化PNP铬系催化剂。     

超支化PNP铬系催化剂的合成及对乙烯齐聚的催化性能EI北大核心CSCD

以正己胺为核的1.0G超支化大分子(R6-1.0G)、氯代二苯基膦和CrCl3(THF)3为原料,合成了一种新型的超支化PNP铬系催化剂(R6-Cat)。红外光谱、核磁共振氢谱和紫外光谱证实合成产物的结构与理论结构相符。在合成的基础上,对该催化剂催化乙烯齐聚的性能进行了研究。考察了溶剂种类、反应温度、Al/Cr比、反应压力等条件对该催化剂催化乙烯齐聚性能的影响。结果表明,当以甲苯为溶剂,甲基铝氧烷(MAO)为助催化剂时,该催化剂表现出良好的催化乙烯齐聚性能。随着反应温度和Al/Cr比的增加,催化活性先升高后降低;而催化活性随着反应压力的增加而增大。当反应温度为35℃、Al/Cr比为500、反应压力为1.0 MPa时,催化活性可达2.02×104 g/(mol Cr·h),聚合产物主要是C8以下的低碳烯烃,含量高达92%以上。相同条件下,其催化乙烯齐聚的活性高于与其结构类似但烷基链长度不同的超支化PNP铬系催化剂。     

Chemical modification of flexible and rigid poly(vinyl chloride) by nucleophilic substitution with thiocyanate using a phase-transfer catalyst

The purpose of this study was to examine the effect of a phase-transfer catalyst on the chemical modification of flexible and rigid poly(vinyl chloride) (PVC) by substituting chloride with thiocyanate (SCN) in order to develop a new process for recycling PVC. The effects of temperature and time on the reaction of a SCN/ethylene glycol (EG) solution on PVC were investigated in the presence and absence of tetrabutylammonium bromide (TBAB) as a phase-transfer catalyst. TBAB was found to accelerate the dehydrochlorination of both flexible and rigid PVC, thus allowing the reaction to take place over shorter reaction times. The substitution yield and substitution/dehydrochlorination ratio were higher in the presence of TBAB than in its absence. By reducing the reaction temperature, the substitution/dehydrochlorination ratio increased, and substitution occurred more rapidly when TBAB was present. The differences between flexible and rigid PVC were negligible. Together, these results indicate that the phase-transfer catalyst TBAB is effective in accelerating the substitution of chloride by SCN. This two-phase reaction allows for the easy separation of the polymer from the solvent without using other chemicals or thermal processes.     

Synthesis and characterization of PVAm/SBA-15 as a novel organic–inorganic hybrid basic catalyst

Composite polyvinyl amine/SBA-15 (PVAm/SBA-15) in various amounts of SBA-15 were prepared and characterized. The physical and chemical properties of PVAm/SBA-15 were investigated using FT-IR, XRD, BET, SEM and TGA techniques. The catalytic performance of each material was determined for the Knoevenagel condensation reaction between carbonyl compounds and ethyl cyanoacetate in the presence of ethanol as solvent. The effects of reaction temperature, solvent and the amounts of catalyst as well as recyclability of the catalyst were investigated. The catalyst used for this synthetically useful transformation showed a considerable degree of reusability besides being very active.     

竹炭基固体酸催化剂的制备及其催化性能研究

以4年生慈竹为炭源制备新型碳基固体强酸催化剂,以油酸与甲醇的酯化反应为模型反应主要考察了炭化温度、炭化时间、磺化温度和磺化时间等因素对其催化剂性能的影响。研究结果表明,以竹子作为碳源,利用硫酸合成碳基固体酸催化剂的最佳工艺条件为:碳化温度650℃,碳化时间6h,磺化温度140℃和磺化时间10h,在此条件下油酸与甲醇的酯化反应的转化率达到94.70%。竹炭基固体酸催化剂制备简单,催化酯化反应条件温和,克服了传统液体酸催化剂的缺点,具有良好的稳定性,且通过简单的过滤即可回收重复利用具有很好的应用前景。     

乳化炸药中硝酸铵-亚硝酸钠的发泡动力学研究

为了了解和控制乳化炸药中硝酸铵-亚硝酸钠反应的发泡速率,采用减重法和量气法研究了该反应过程的反应机理和反应动力学。结果表明,酸可作为催化剂,对整个反应过程起促进作用;其次,在酸作为催化剂条件下,反应速率随着实验温度的增加而增加,且反应符合Arrhenius模型。其中,反应活化能为57.87 kJ/mol,指前因子为1.48×10~6 mol/L·s。对比实验值和计算值可知,反应动力学方程合理。为实际生产中化学敏化反应速率的控制提供了理论依据。     

单因素对单分散二氧化硅微球制备的影响

以氨水为催化剂、正硅酸乙酯为硅源、醇为溶剂,采用改进的溶胶-凝胶工艺制备单分散SiO2微球,通过扫描电镜、激光粒度分析仪着重研究了正硅酸乙酯添加方式、反应温度、溶剂类型等单因素对SiO2的颗粒大小和形貌的影响.结果表明,正硅酸水解对醇溶剂是有选择性的,乙醇作为溶剂合成SiO2的单分散性和球形度最好.连续滴定和分步滴定更有利于单分散SiO2微球的形成.水解温度升高,生成的颗粒粒径将运渐增大,最佳反应温度为常温25℃或恒温水浴25～35℃.     

季铵盐对热熔预浸料用环氧树脂胶膜室温贮存期的影响

采用通常用作阳离子型表面活性剂和相转移催化剂的苄基三乙基氯化铵,作为酸酐/环氧树脂体系的促进剂,制备了复合材料预浸料用环氧树脂胶膜,研究了其室温和高温固化特征。结果表明,与咪唑类促进剂相比,季铵盐作促进剂的环氧树脂室温固化反应速率小,而高温固化反应速率和凝胶时间几乎相等,在保证环氧树脂固化体系高温固化速率的前提下,季铵盐对环氧树脂胶膜的室温固化产生明显的阻缓作用,实测环氧树脂胶膜室温贮存期由使用咪唑类的5 d延长为8 d,理论室温极限贮存时间由8 d延长为11 d。     

直接法制备三甲氧基硅烷的正交实验研究

为提高产率、降低成本,采用反歧化法制备了催化剂氯化亚铜,研究了硅粉和氯化亚铜经过微波预处理直接法合成三甲氧基硅烷,利用XRD、XRF、SEM对催化剂进行了表征.用正交实验方法探索了不同工艺条件对硅粉转化率、产物选择性和产物收率的影响.正交实验表明,各因素对产物收率影响的由大至小顺序为：硅粉占溶剂质量比例、反应温度、甲醇...     

Graphene oxide : a novel acid catalyst for the synthesis of 2,5-dimethyl-N-phenyl pyrrole by the Paal-Knorr condensation北大核心CSCD

Graphene oxide (GO) was used as an efficient and recyclable catalyst for the synthesis of N-substituted pyrrole using a Paal-Knorr condensation reaction between 2,5-hexanedione and aniline. The effects of reaction time, reaction temperature, solvent, catalyst loading and molar ratio of aniline to 2,5-hexanedione on the yield of 2,5-dimethyl-N-phenyl pyrrole were investigated. In situ NMR was used to follow the Paal-Knorr reaction at the molecular level. Results revealed that the oxygen-containing groups of GO, such as sulfonic acid and carboxyl groups, played a key role in this catalytic reaction. Polar protic solvents were favorable for the reaction. The catalytic activity increased with temperature without any side reaction. The GO could be easily recovered and showed remarkable reusability and excellent catalytic performance allowing it to be reused 5 times.     

Palladium-catalyzed hydrodehalogenation of 1,2,4,5-tetrachlorobenzene in water-ethanol mixtures

Palladium-catalyzed hydrodehalogenation (HDH) was applied for destroying 1,2,4,5-tetrachlorobenzene (TeCB) in mixtures of water and ethanol. This investigation was performed as a critical step in the development of a new technology for clean-up of soil contaminated by halogenated hydrophobic organic contaminants. The main goals of the investigation were to demonstrate the feasibility of the technology, to determine the effect of the solvent composition (water:ethanol ratio), and to develop a model for the kinetics of the dehalogenation process. All experiments were conducted in a batch reactor at ambient temperature under mild hydrogen pressure. The experimental results are all consistent with a Langmuir-Hinshelwood model for heterogeneous catalysis. Major findings that can be interpreted within the Langmuir-Hinshelwood framework include: (1) the rate of hydrodehalogenation depends strongly on the solvent composition, increasing as the water fraction of the solvent increases; (2) the HDH rate increases as the catalyst concentration in the reactor increases; (3) when enough catalyst is present, the HDH reaction appears to follow first-order kinetics, but the kinetics appear to be zero-order at low catalyst concentrations. TeCB is converted rapidly and quantitatively to benzene, with only trace concentrations of 1,2,4-trichlorobenzene appearing as a reactive intermediate. The results obtained here have important implications for the further development of the proposed soil remediation technology, and may also be important for the treatment of other hazardous waste streams.     

Solvent extraction of chlorinated compounds from soils and hydrodechlorination of the extract phase

The remediation of soils contaminated with chlorinated compounds was investigated. The process consists of solvent extraction followed by catalytic hydroprocessing (hydrodechlorination) of the extract phase. A mixture of ethylacetate-acetone-water (E-A-W) was adopted as solvent in the extraction process. Tests of extraction of chlorobenzene from a model contaminated soil were carried out and the Langmuir adsorption equation was characterized. The solvent, contaminated with different chlorinated compounds was then hydrotreated with a Pd/C catalyst. The chlorinated compounds tested are: chlorobenzene, hexachlorobenzene and hexachloroethane at various initial concentrations. The reaction runs were carried out at room temperature and at a hydrogen pressure of 1bar. Hydrotreating of these compounds takes place according to a Langmuir-Hinshelwood mechanism whose kinetic parameters were determined. The experiments show that high destruction efficiencies may be reached in reasonably short times, particularly for hexachloroethane. Longer times are necessary for the aromatic compounds (chlorobenzene and hexachlorobenzene) for which the CCl bond is much stronger than that in the aliphatic compound. Time for a 95% destruction efficiency for all experimental runs was determined. A noteworthy finding is that ethylacetate and acetone do not undergo any reaction during hydrotreating. Thus the treated extract solution may be recycled inasmuch as it conserves its full extracting capacity towards chlorinated compounds. A limitation in recycling is the inhibiting effect of benzene on the HDCl rate: benzene produced by HDCl of chlorinated compounds, accumulates in the solvent mixture in the event of recycling. Simulation of the process with the recycling of the solvent was carried out, accounting for the inhibiting effect of benzene.