醇溶剂中TS-1催化丙烯环氧化的本征动力学与反应机理研究

研究了在三种不同醇溶剂(甲醇、异丙醇和仲丁醇)水溶液中TS—l催化丙烯过氧化氢环氧化反应的本征动力学，反应条件为温度30～60℃，丙烯压力0．4-0．6MPa。根据实验现象和各组分在TS-1上的吸附特点建立了该反应的Eley-Rideal机理模型，环氧化反应在吸附态的H2O2分子与游离态的丙烯分子之间进行，表面反应为速度控制步骤。通过实验数据对机理模型进行了参数估值，检验结果表明拟合效果较好，平均偏差在10％以内。最后对过程进行了进一步讨论，为该过程的工业化提供了依据。     

Regeneration of Lamina TS-1 Catalyst in the Epoxidation of Propylene with Hydrogen Peroxide

The deactivation and regeneration of the lamina titanium silicalite (TS-1) catalyst for the epoxidation of propylene with dilute H₂O₂was investigated in a fixed-bed reactor. In the scale-up experiment, the dosage of the lamina TS-1 catalyst is 2. 5 kg, after 1000 h reaction the catalyst still exhibits good performance and further increases the reaction time, the conversion of H₂O₂begins to decrease. TG and BET analyses of the deactivated catalysts show that the main species occluded within the zeolite pore are propylene oxide oligomers, and these species occupying the active Ti site and blocking the pores of the lamina TS-1 are the main reason for the deactivation of catalyst. The deactivated catalyst can be regenerated by different regeneration methods. The activity of deactivated catalysts regenerated by dilute H₂O₂or heat treatment by using air or nitrogen as a calcination media can be fully recovered, but a decline in propylene oxide (PO) selectivity of the regenerated catalyst has been observed during the first hours of reaction. However, water vapor treatment of the deactivated catalyst can improve the PO selectivity with the same activity as that of the fresh lamina TS-1 catalyst.     

Preparation and Catalytic Performance in Propylene Epoxidation of Hydrophobic Hierarchical Porous TS-1 Zeolite

Catalysis Letters - The contribution introduced a new type of titanosilicate molecular sieve HTS-1-X with high specific surface area, high titanium content, hierarchical pores, hydrophobicity, and...     

W/O型微乳液最大增容水量的研究

研究了电导率测定微乳液的最大增溶水量及最大增溶水量的影响因素。以Span80和Tween80为复配表面活性剂,正辛烷作为油相,在超声波作用下制备微乳液;利用电导率仪测定微乳液的电导率,利用Original lab绘图软件对得到的电导率作图,通过曲线的突变点来确定微乳液的最大增溶水量。亲水亲油平衡值(HLB)和表面活性剂浓度是微乳液最大增溶水量的两个主要影响因素,通过研究它们的变化对最大增溶水量的影响,我们得出了较佳的微乳液最大增溶水量。     

Epoxidation of Propylene with Hydrogen Peroxide Over TS-1 Catalyst Synthesized in the Presence of Polystyrene

Titanium silicalite-1 (TS-1) catalyst was synthesized in the presence of polystyrene (PS) particles (denoted as TS-1_PS catalyst) for use in the epoxidation of propylene with hydrogen peroxide. For the purpose of comparison, TS-1 catalyst was also synthesized by a conventional method (in the absence of polystyrene particles). In the epoxidation of propylene, the TS-1_PS catalyst showed a higher conversion of hydrogen peroxide and a higher selectivity for propylene oxide (PO) than the TS-1 catalyst. Consequently, the TS-1_PS catalyst showed a higher yield for PO than the TS-1 catalyst. Characterization results showed that the high catalytic performance of TS-1_PS was attributed to the enhanced hydrophobic property of the catalyst and the suppressed formation of anatase TiO₂ in the catalyst.     

Influence of Surfactant on the Characteristics of W1/O/W2-Microparticles

The water-in-oil-in water (W₁/O/W₂) double emulsion evaporation technique is widely used when the microencapsulation of soluble agents like naloxone HCl is intended. The present work shows the effect of HLB emulsifiers added to phase O on microsphere morphology, size, release, drug encapsulation efficiency. The addition of sorbitan ester to first emulsion (W₁/O) and the HLB of the surfactant have an important effect on the characteristics of poly-lactide-co-glycolide (PLGA) microparticles (MP). This MP with sorbitan esters added were smaller and released the hydrophilic drug, naloxone, with no-significant difference at pH 5 versus pH 7.5 (phosphate medium). This is an important fact when long-drug release is considered since it is known that PLGA degradation leads to media acidification. The HLB value had an important effect on drug loading. Sorbitan monooleate led to the highest naloxone loading. Because of its low HLB (4.3), it is most suitable for stabilizing the W₁/O emulsion, which is fundamental for the successful entrapment of a hydrophilic compound in MP prepared by double emulsion technique. Finally, drug solubility in the MP matrixes cannot be considered as a predictive parameter for drug encapsulation. Both surfactants increased the naloxone solubility in the polymer PLGA and only sorbitan monooleate increased the drug entrapment.     

水/油/水双重乳液系统内的水传递机理

利用毛细显微摄像技术直观、实时地研究了水/油/水双重乳液系统在不同油膜厚度情况下的水传递过程并测得了水传递速率.根据实验观察提出了一种新的水传递机理,即水以自发乳化的方式传递.控制水传递速率的传递机理因为油膜厚度的不同而变化当油膜厚度很小时,内、外水相处于相互接触位置,水主要通过表面活性剂水化的方式传递,且速率很大;当油膜厚度比较大时,内、外水相不接触,水主要通过自发乳化和形成反胶束的方式传递,速率相对较低.另外,研究还排除了水分子直接通过由于油膜厚度波动形成的表面活性剂薄层来传递的机理.     

胰岛素W/O型微乳液的制备及体外释药性能

制备了包封胰岛素(INS)的Tween 80-Span 80/乙醇/丁酸乙酯/水体系的W/O型微乳液。以最大增溶水量为指标,选择了合适的微乳液组分包封INS。考察了温度、盐度和pH对微乳液区域的影响。电导率法区分了微乳液的O/W、W/O和B.C.区域。动态光散射测定了微乳液的粒径和多分散度。125I同位素示踪法测定了INS微乳液体外释放效果。结果表明,微乳体系在水/乙醇(质量比为1.8∶1)的质量分数小于41%时形成W/O型微乳液,温度、盐度升高和pH降低使微乳区稍有减小。微乳液粒径和多分散度分别为35~45 nm和0.29~0.37。pH的降低对微乳液粒径影响不大,而药物的加入使微乳液粒径略有减小。载药微乳液粒径在制备3 d后突降,以后的27 d内保持在37 nm左右。该载药微乳液在7.5 h后进入缓释阶段,40 h时INS的释放率为66.20%。     

Surface-Initiated Gas-Phase Epoxidation of Propylene with Molecular Oxygen by Silica-Supported Molybdenum Oxide: Effects of Addition of C3H8 or NO and Reactor Design

The gas-phase epoxidation of propylene was studied over MoO _x /SiO₂ catalysts in a reaction system with a post-catalytic bed volume. In the reaction of a mixture of propylene and propane with oxygen below 578 K, propylene oxide (PO) was mainly formed from the oxidation of propylene. It was found that the oxidation reaction was very sensitive to the temperature of the post-catalytic space more than the temperature of the catalyst bed, strongly indicating that radical reactions occurring in the post-catalytic bed free space were responsible for the PO formation. The addition of NO increased propylene conversions and PO selectivity at low conversions, confirming that radical reactions were involved in the propylene reactions.     

Epoxidation of allyl alcohol to glycidol using titanium silicalite TS-1: effect of the method of preparation

The epoxidation of allyl alcohol with hydrogen peroxide catalysed by the microporous titanium silicalite TS-1 has been investigated with respect to the effect of the method of catalyst preparation. Three methods of TS-1 synthesis have been studied using the standard tetrapropyl-ammonium cation as template (i) using tetraethyl orthosilicate, tetraethyl orthotitanate as reagents, (ii) using a fluoride method and (iii) using tetrabutyl orthotitanate as the titanium source. The TS-1 samples were characterised by electron microscopy, X-ray diffraction and infrared spectroscopy. The method of preparation controlled the morphology of the TS-1 crystals and in particular the crystallisation time was found to be an important parameter. Data are presented that correlate the activity for the epoxidation of allyl alcohol with the morphology of TS-1. In addition it is found that the catalytic activity of TS-1 for this reaction is not related to the intensity or presence of the infrared absorption band at ca. 960 cm^–1.     

电导率法研究W/O微乳液中Pd纳米微粒的化学破乳负载

利用水-Tween-80-Span-80-环己烷微乳液合成了粒径为5~10 nm、高度分散的Pd纳米微粒. 结果表明,随着破乳剂用量的增大,含Pd微乳液与破乳剂的混合体系依次呈现微乳液、分层、胶体或微乳液体系. 破乳剂的亲水性与分子结构是影响破乳行为的主要参数. 利用混合物体系分层与再均相的临界区域,在微乳液浸渍a-Al2O3载体的同时,使其中的Pd纳米微粒破乳沉积,实现了Pd在载体表面的均匀负载. TEM及XPS分析表明,Pd的微粒粒径为10~20 nm, 以单质形态结合于载体表面.     

Regimes of Multiple Emulsions of W1/O/W2 and O1/W/O2 Type in the Continuous Couette‐Taylor Flow Contactor

The flow regimes of multiple emulsions in the continuous Couette‐Taylor flow (CTF) contactor and characterization of the dispersion state are reported. The proposed method of multiple emulsion preparation is a one‐step procedure on the contrary to the classical two‐step procedure. The effect of operating parameters in the CTF contactor on multiple emulsion appearance, structure (drop size and packing), and rheological behavior is discussed. The key factors affecting multiple emulsion preparation in the CTF apparatus were the phases ratio, the rotational flow, and an annular gap width. The influence of an axial flow was more significant in the range of small rotational rates. The operating conditions were optimized to find the best characteristic multiple emulsions (largest interfacial area). The paper presents the same exemplary data of using W₁/O/W₂ emulsions as emulsion liquid membranes (ELMs) in the extraction process and O₁/W/O₂ for control active agent (drug) release.     

Epoxidation of allyl alcohol to glycidol using titanium silicalite TS-1: effect of the reaction conditions and catalyst acidity

The epoxidation of allyl alcohol to glycidol using the titanium silicalite TS-1 with hydrogen peroxide as the oxidant is described and discussed in detail. The reaction conditions (alcohol, solvent, temperature) required to obtain 100% selectivity to glycidol are described and this selectivity has been observed at conversions of allyl alcohol of up to 20%. Addition of excess hydrogen peroxide enhances conversion but does not appear to affect selectivity to glycidol deleteriously, whereas addition of hydrogen peroxide over an extended time period is not particularly beneficial. The major side reactions are the oxidation of the alcohol solvent and the ring opening solvolysis of the glycidol that leads to the formation of alkoxy diols. Base treatment of the TS-1 using sodium azide enhances the glycidol selectivity, whereas the incorporation of Brønsted acid sites by addition of aluminium into the framework structure of TS-1 enhances the selectivity to the products of solvolysis ring opening reactions.     

Au/TS-1的合成及其对环己烷氧化反应的影响

用不同的:实验方法制备得到了钛硅负载金催化剂(Au/TS-1).并用于催化环己烷液相选择氧化反应。发现以无机钛硅为原料水热合成得到的Au/TS-1催化剂具有良好的催化性能;在反应体系中以氧气作为氧化剂,考察了反应时间、温度、压力等因素对催化剂活性的影响。结果表明,当叔丁基过氧化氢用量为0.04 g时,在150℃,1.0 MPa的条件下反应2.5 h,环己烷的转化率达到了9.42%,目的产物(环己醇、环己酮和环己基过氧化氢)的选择性为89.38%。     

Resistance to sulfidation of the catalytic reduction of NOx over Ag/Al2O3 by controlling the loadings of Ag and Ag+

SO₂ strongly decreased the catalytic activities of low loading Ag/Al₂O₃ below 500 °C in selective catalytic reduction (SCR) of NO_x by propene with or without the assistance of non-thermal plasma (NTP), which was mainly attributed to the competition between SO₂ and NO. By controlling the loadings of Ag and Ag⁺ over alumina, the resistance of SO₂ was remarkably enhanced between 400 °C and 500 °C in thermal SCR. In the NTP-assisted SCR, most of the NO_x conversions were also apparently recovered from 250 °C to 500 °C.     

Highly Active/Selective Heterogeneous Catalyst Co/Ts-1 for Epoxidation of Styrene by Molecular Oxygen: Effects of Catalyst Preparation Conditions and Reaction Conditions on the Reaction

In the study, highly active/selective heterogeneous catalyst Co/TS-1 has been prepared successfully. The catalyst was characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), diffuse reflectance UV–visible(DR UV–vis) and transmission electron microscopy (TEM). Liquid-phase catalytic epoxidation of styrene to styrene epoxide by molecular oxygen was carried out at atmospheric pressure in the presence of Co/TS-1 catalyst. Sacrificial co-reductant or other promoted reagent such as t-butyl hydroperoxide (TBHP) was not added in the reaction system. A 94.5 mol% conversion of styrene with an epoxide selectivity of 74.3 mol% was attained after 3.5 h reaction. It is noteworthy that there is a synergy between the Co and the Ti in the catalyst in the liquid phase epoxidation of styrene.     

C12G1.50/正丁醇/环己烷/H2O W/O体系中的酶催化酯合成反应研究

研究了在十二烷基聚葡糖苷C12G150/正丁醇/环己烷/H2O体系形成的油包水(W/O)微乳液中,脂肪酶Novozym100T催化正己酸和正丁醇的酯合成反应及其影响因素。结果表明,反应初始速率V0随正己酸的初始浓度CHA0增大而增大;随正丁醇的初始浓度CROH0的增大而减小,后V0进入一"坪区"。这可能是形成酶-正丁醇络合物所致。C12G1.50、正丁醇的浓度及两者的总浓度对初始浓度的影响也进行了讨论。     

微乳液法制备条件对纳米SiO_2粒子形貌和粒径分布的影响

研究TritonX - 10 0 /正辛醇 /环己烷 /水 (或氨水 )微乳液稳定相行为与制备条件的关系 ,发现K〔m(TritonX - 10 0 )∶m(正辛醇 )〕 =1 5 ,而水相是氨水时微乳液系统有较宽单相W/O型微乳区 ,是正硅酸乙酯 (TEOS)水解制备纳米SiO2 粒子的适宜介质系统。在h〔n(H2 O)∶n(TEOS)〕 =4 ,R〔n(H2 O)∶n(TritonX - 10 0 )〕 =6 5和K =1 5的条件下 ,TEOS受控水解制得疏松球形无定形晶态SiO2 粒子 ,粒度分析表明 99 7%粒径为 4 0～ 5 0nm     

W_1/O/W_2乳液油相薄化速率的影响因素

用乳粒发生器制备约2 mm的大直径W1/O/W2乳粒,研究了油相中Span80和水相中CaCl2对油膜薄化的影响,同时也研究了外相水用氟苯(FB)溶剂饱和后对双重乳粒体系油膜薄化的影响。结果表明:Span80和CaCl2的浓度越大,油相的薄化速率越大;外相水中FB的加入将降低乳液体系油相的薄化速率。