共查询到16条相似文献,搜索用时 156 毫秒
1.
Fe(acac)3-Al(i-Bu)3-CCl4催化马来酸酐与降冰片烯共聚 总被引:1,自引:0,他引:1
研究了Fe(acac)3-Al(i-Bu)3-CCl4(acac=乙酰丙酮)催化体系对马来酸酐(MA)与降冰片烯(NBE)交替聚合反应的催化性能. 用元素分析、核磁共振和红外光谱研究了共聚物的结构,在单体比为1∶1时,共聚物中MA和NBE的含量分别为52.2%和47.8%. 凝胶渗透色谱结果表明共聚物分子量分布窄. 动力学研究结果表明, MA与NBE共聚对单体浓度呈一级反应,其表观活化能为74.3 kJ/mol. 相似文献
2.
3.
4.
5.
6.
7.
8.
9.
研究了FeCl2-Al(i-Bu)3-phen胶体催化剂各组分的配比、加入顺序、陈化等制备因素对催化性能的影响。由于各组分之间形成活性位的反应是快速反应,只有按phen FeCl3 Al(i-Bu)3的加入顺序,才能有效阻止深度还原;陈化能提高稳定和较稳定的胶体催化体系的催化活性,而对于不稳定体系,采用“单加”较适宜。陈化时加少量丁二烯,其催化活性高于不加丁二烯的,这是由于生成的丁二烯聚合物可起空间稳定作用,阻碍胶粒聚结,使其稳定在小颗粒范围内;采用适宜的[phen]:[Fe]:[Al]比,可制备出小而均匀的催化剂颗粒,且有利于还原生成活性位所需的Fe^2 ,同时得到相对稳定的胶体催化体系。 相似文献
10.
11.
12.
13.
José Bonilla-Cruz Laura Caballero Martha Albores-Velasco Enrique Saldívar-Guerra Judith Percino Víctor Chapela 《Macromolecular Symposia》2007,248(1):132-140
Recently we reported an experimental and theoretical (simulation) investigation on the mechanism of the induction period and the initial polymerization stages in the nitroxide mediated autopolymerization of styrene. In this paper we extend some of the results presented there and perform preliminary induction period experiments for the study of the mechanism and kinetics of the spontaneous copolymerization of styrene (S) and maleic anhydride (MA) in the presence of TEMPO and 4-OH-TEMPO. With even small amounts of MA (2% wt) the induction period is dramatically reduced by a factor of about 20 in comparison with the nitroxide-mediated styrene autopolymerization at 120 °C. Our results suggest that the initiation mechanism involves a first step of reaction between S and MA. We speculate that this reaction is a Diels-Alder cycloaddition followed by hydrogen abstraction through a monomer or TEMPO assisted homolysis to form a radical pair (monomer case) or a single radical (TEMPO case), which either initiates polymerization or is trapped by TEMPO depending on the conditions. Hall and Padias have studied similar electron donor-acceptor co-monomer pairs and favor the formation of a tetramethylene diradical as the initiating species for spontaneous copolymerization. In any case, the rate-limiting step would be the initial reaction of S and MA. These induction experiments allow us to obtain an initial estimate of the order of magnitude for the kinetic constant of the rate-limiting step, as 10−6 Lmol−1s−1. 相似文献
14.
顺酐催化氢化反应中琥珀酸酐的气相色谱分析 总被引:1,自引:0,他引:1
In this paper,a gas chromatographic method for the quantitative determination of succinic anhydride incatalytic hydrogenation of maleic anhydride is presented.The experimental results show that the use of SE-30,1,4-butylrolactone and chforoform as stationary phase,internal standard and solvent respectively is appropriate. 相似文献
15.
在杷来酸酐-苯乙烯本体聚合反应过程中,于70℃和低引发剂浓度(0.59-1.8×10^-3mol/L条件下,共聚物组成与单体的配比无关,生成无规共聚物;在高引发剂浓度(2×10^-2mol/L),随马来酸酐单体含量的增加,趋向生成1:1交替共聚物,温度的提高可以使生砀共聚物结构向1:1组成移动,当温度超过140℃时将生成无规共聚物,在本体聚合反应体系中,存在共聚反应和苯乙烯的均聚反应,而且随着的提 相似文献
16.
正丁烷氧化制顺酐流化床催化剂的性能 总被引:1,自引:0,他引:1
考察了前驱体制备过程中水合肼/五氧化二钒摩尔比(以下简记\r\n为n(N2H4)/n(V2O5))对催化剂性能的影响.由较高的n(N2H4)\r\n/n(V2O5)比制得的催化剂,其(VO)2P2O7相含量较多,正丁烷转化\r\n率较高.随着n(N2H4)/n(V2O5)比的减小,δ-VOPO4相的含量逐\r\n渐增多,正丁烷转化率随之升高;而顺酐选择性开始时升高,达到最大\r\n值后逐渐降低.在n(N2H4)/n(V2O5)=0.34时制备的催化剂最佳\r\n,在丁烷浓度为4.0%、空速为500h-1及反应温度为420℃的反应条件\r\n下,顺酐收率可达49.74%.本文中细粒床催化剂有较大的操作弹性. 相似文献