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1.
TiCl4/SiO2负载型催化剂用于丁二烯聚合——I.催化剂制备条件对聚合的影响 总被引:2,自引:2,他引:0
用球磨法制备的SiO2负载TiCl4催化剂进行丁二烯溶液聚合,考察了催化剂制备条件对催化效率的影响,分析了聚合物的结构。结果表明:球磨48h,负载钛质量分数4%的催化剂具有较好的催化效率;SiO2在负载TiCl4前用适量Al(i-Bu)3处理,或将球磨法制备的TiCl4/SiO2催化剂与适量Al(i-Bu)2Cl在100℃下反应1h,均能大幅度提高催化剂的活性;在40~50℃下,聚合按溶液淤浆聚合形式进行,产物为低顺式聚丁二烯。 相似文献
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用球磨法制备的SiO_2负载TiCl_4催化剂进行丁二烯溶液聚合,考察了催化剂制备条件对催化效率的影响,分析了聚合物的结构。结果表明:球磨48 h,负载钛质量分数4%的催化剂具有较好的催化效率;SiO_2在负载TiCl_4前用适量Al(i-Bu)_3处理,或将球磨法制备的TiCl_4/SiO_2催化剂与适量Al(i-Bu)_2Cl 在100 ℃下反应1 h,均能大幅度提高催化剂的活性;在40~50 ℃下,聚合按溶液淤浆聚合形式进行,产物为低顺式聚丁二烯。 相似文献
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TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅱ.聚合条件及聚合动力学 总被引:1,自引:1,他引:0
《合成橡胶工业》2001,24(5):281-284
使用以球磨法制备的SiO2负载TiCl4催化剂进行丁二烯溶液聚合,考察了聚合条件对催化效率的影响以及在20~60℃下的聚合动力学.确定了适宜的聚合条件以加氢汽油为溶剂,Al/Ti摩尔比为20,Ti/Bd摩尔比为2×10-4,50℃聚合10h以上.溶液聚合动力学研究结果表明,本体系在低转化率下为稳态聚合,其稳态聚合速率方程为Rp=kpf[Ti]0[Bd],聚合的表观活化能为11.4kJ/mol. 相似文献
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TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅱ.聚合条件及聚合动力学 总被引:1,自引:1,他引:0
使用以球磨法制备的 SiO2负载 TiCl4催化剂进行丁二烯溶液聚合,考察了聚合条件对催化效率的影响以及在 20~ 60℃下的聚合动力学。确定了适宜的聚合条件:以加氢汽油为溶剂, Al/Ti摩尔比为 20, Ti/Bd摩尔比为 2× 10- 4, 50℃聚合 10 h以上。溶液聚合动力学研究结果表明,本体系在低转化率下为稳态聚合,其稳态聚合速率方程为 Rp=kpf[Ti]0[Bd],聚合的表观活化能为 11.4 kJ/mol。 相似文献
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研究了含Mg载体ClMg(OR)·ROH(R为乙基和正丁基)的制备和反应机理。分别以CH2Cl2,CHCl3,CCl4作为溶剂,在n(C2H5OH)/n(Mg)为2.0的条件下,可以合成ClMg(OC2H5)·C2H5OH载体,并且成本较低。采用ClMg(OR)·ROH为载体与TiCl4反应,制备了乙烯聚合用负载型催化剂,研究了该催化剂的制备规律和催化乙烯聚合的性能。结果表明:以ClMg(OC4H9)·C4H9OH为载体制备TiCl4/MgCl2催化剂,载Ti时间为2 h,载Ti温度为110℃,TiCl4用量为2.0 mL/g,载Ti次数为3次时,制备的负载型催化剂催化乙烯聚合具有较高的活性,可达4.6 kg/(g·h)。 相似文献
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合成了一种新的同双核钛茂金属催化剂[(CH3C5H4)TiCl2]2[C5H4CH2CH2OCH2CH2C5H4](A),用元素分析和1H-NMR进行了表征.在助催化剂的作用下,该催化剂体系可有效催化甲基丙烯酸甲酯(MMA)本体和溶液聚合.考察了助催化剂、反应温度和时间对聚合的影响.结果表明,Al(i-Bu)3催化性能优于Al(Et)3和甲基铝氧烷(MAO).以Al(i-Bu)3为助催化剂,本体聚合在MMA和A的摩尔比为1 500,Al(i-Bu)3和A的摩尔比为20,60 ℃,反应时间20 h条件下,单体转化率达98.6%,PMMA的粘均分子量为 7.87×105;溶液聚合在MMA和A的摩尔比为1 500,Al(i-Bu)3和A的摩尔比为20,80 ℃,反应时间15 h条件下,单体转化率77.3%,PMMA的粘均分子量3.24×105.聚合所得PMMA分子量分布为5.0~7.0. 相似文献
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在WCl_6-C_4H_(?)OH催化体系中各种助催化剂对聚合活性的影响表明,以Al(i-Bu)_(?)为助催化剂体系的聚合活性最高,AlEt_2Cl和AlEt_3体系的聚合活性相近;CH_3PhOH/Al(i-Bu)_3=1(mol比)的助催化剂体系和Al(i-Bu)_3体系的聚合活性相近,但适宜Al/W(mol比)的范围增宽,醇类作助催化剂的配位体时,体系的聚合活性降低;在实验条件下,Al(i-Bu)_2H体系无聚合活性;以AlEt_3、Al(i-Bu)_3、Al(i-Bu)_2OPhCH_3和Al(i-Bu)_2OC_4H_(?)分别作助催化剂时,对产物分子量影响较小,并均能得到1,2-结构含量大于85%的1,2-聚丁二烯。 相似文献
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Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu2O, Bi2O3 and ZnMn2O4 are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu2O/TiO2 and Bi2O3/TiO2 by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed. 相似文献
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Surface-phase ZrO2 on SiO2 (SZrOs) and surface-phase La2O3 on Al2O3 (SLaOs) were prepared with various loadings of ZrO2 and La2O3, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH4/CO2 reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al2O3 and Pt/SiO2 catalysts. CO2 or CH4 pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides.
The zirconia can be homogeneously dispersed on SiO2 to form a stable surface-phase oxide. The lanthana cannot be spread well on Al2O3, but it forms a stable amorphous oxide with Al2O3. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO2 and Pt/Al2O3 by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO2 and Pt/Al2O3 catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO2 adsorbed on the basic sites of SZrOs and SLaOs. 相似文献
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以冰乙酸和异戊醇为原料,Al_2(SO_4)_3/FeCl_3为催化剂,对催化合成乙酸异戊酯的条件进行研究。考察催化剂用量、乙酸与异戊醇物质的量比以及反应时间对乙酸酯化率的影响。结果表明,Al_2(SO_4)_3/FeCl_3具有良好的催化活性,在乙酸物质的量为0.1 mol、乙酸与异戊醇物质的量比为1∶4、催化剂用量1.0 g、反应时间2.0 h和带水剂环己烷用量10 m L反应条件下,重复实验3次,平均乙酸酯化率为93.50%。 相似文献
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稀土固体超强酸SO2-4/TiO2/La3+催化合成醋酸丁酯 总被引:13,自引:0,他引:13
《化学世界》2001,42(12):653-654
研究了以固体超强酸SO24-/TiO2/La3+催化剂,醋酸和正丁醇为原料合成醋酸丁酯,并考察了影响反应的因素.结果表明醇酸物质的摩尔比为1.61、催化剂用量0.6
g、带水剂甲苯7 mL、反应时间2.5 h是最适宜的反应条件,其酯化率可达96.2%. 相似文献
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Free acids of the iron substituted heteropoly acids (HPA), H7[(P2W17O61)FeIII(H2O)] (HFe1) and H18[(P2W15O56)2FeIII2(H2O)2] (HFe2) were prepared from the salts K7[(P2W17O61)FeIII(H2O)] (KFe1) and Na12[(P2W15O56)2FeIII4(H2O)2] (NaFe4), respectively. The iron-substituted HPA were adsorbed on to XC-72 carbon based GDLs to form HPA doped GDEs after water washing with HPA loadings of ca. 1 μmol. The HPA was detected throughout the GDL by EDX. Solution electrochemistry of the free acids are reported for the first time in sulfate buffer, pH 1-3. The hydrogen oxidation reaction was catalyzed by KFe1 at 0.33 V, with an exchange current density of 38 mA/cm2. Moderate activity for the oxygen reduction reaction was observed for the iron substituted HPA, which was dramatically improved by selectively removing oxygen atoms from the HPA by cycling the fuel cell cathode under N2 followed by reoxidation to give a restructured oxide catalyst. The nanostructured oxide achieved an OCV of 0.7 V with a Tafel slope of 115 mV/decade. Cycling the same catalysts in oxygen resulted in an improved catalyst/ionomer/carbon configuration with a slightly higher Tafel slope, 128 mV/decade but a respectable current density of 100 mA/cm2 at 0.2 V. 相似文献
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Qingzhao Li Changsui Zhao Xiaoping Chen Weifang Wu Baiquan Lin 《Chemical Engineering and Processing: Process Intensification》2010
Pulverized coal combustion in O2/N2 and O2/CO2 environments was investigated with a drop tube furnace. Results present that the reaction rate and burn-out degree of O2/CO2 chars (obtained in O2/CO2 environments) are lower than that of O2/N2 chars (obtained in O2/N2 environments) under the same experimental condition. It indicates that a higher O2 concentration in O2/CO2 environment is needed to achieve the similar combustion characteristic to that in O2/N2 environment. The main differences between O2/N2 and O2/CO2 chars rely on the pore structure determined by N2 adsorption and chemical structure measured by FT-IR. For O2/CO2 char, the surface is thick and the pores are compact which contribute to the fragmentation reduction of particles burning in O2/CO2 environment. The organic functional group elimination rate from the surface of O2/CO2 chars is slower or delayed. The present research results might have important implications for further understanding the intrinsic kinetics of pulverized coal combustion in O2/CO2 environment. 相似文献
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The modification of activated carbon fibres prepared from a commercial textile acrylic fibre into materials with monolithic shape using phenolic resin as binder was studied. The molecular sieving properties for the gas separations CO2/CH4 and O2/N2 were evaluated from the gas uptake volume and selectivity at 100 s contact time taken from the kinetic adsorption curves of the individual gases. The pseudo-first order rate constant was also determined by the application of the LDF model. The samples produced show high CO2 and O2 rates of adsorption, in the range 3-35 × 10−3 s−1, and in most cases null or very low adsorption of CH4 and N2 which make them very promising samples to use in PSA systems, or similar. Although the selectivity was very high, the adsorption capacity was low in certain cases. However, the gas uptake in two samples reached 23 cm3 g−1 for CO2 and 5 cm3 g−1 for O2, which can be considered very good. The materials were heat-treated using a microwave furnace, which is a novel and more economic method, when compared with conventional furnaces, to improve the molecular sieves properties. 相似文献
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A solid state metathesis approach has been applied to synthesize perovskite oxides such as BaTiO3, PbTiO3, K0.5Bi0.5TiO3 and Na0.5Bi0.5TiO3, these were characterized by powder XRD, IR and energy dispersive spectra (EDS). Potassium titanium oxalate and metal chlorides are used as the starting materials. X-ray analysis shows the formation of a single phase with tetragonal structure for BaTiO3, PbTiO3, K0.5Bi0.5TiO3 and a monoclinic structure for Na0.5Bi0.5TiO3. The Infrared spectra of these compounds show the characteristic band due to Ti–O octahedron for all the compounds. The EDS spectra show the relative ratio of the metal ions. The morphology of synthesized compounds was obtained from SEM measurements. 相似文献