无机/有机复合载体负载TiCl3/(n-BuCp)2ZrCl2的乙烯气相聚合

采用溶胶-凝胶法将苯乙烯丙烯酸共聚物(PSA)包裹在负载型Ziegler-Natta催化剂表面,随后用表面改性剂n-BuSnCl3处理有机载体表面的官能团,最后在PSA上负载(n-BuCp)2 ZrCl2制得复合催化剂,研究了复合催化剂的气相聚合行为.实验首先通过BET、粒径分析、红外分析等手段考察了采用n-BuSnC...     

无机/有机复合载体SiO_2/MgCl_2·xBu(OH)_2/PSA负载TiCl_4催化剂的制备及其乙烯聚合行为

采用SiO2、MgCl2以及苯乙烯-丙烯酸共聚物(PSA)合成了SiO2/MgCl2.xBu(OH)2/PSA无机/有机复合载体并负载TiCl4,得到具有SiO2无机支撑层、MgCl2.xBu(OH)2加合物以及PSA有机载体3种化学环境的SiO2/MgCl2.xBu(OH)2/PSA/TiCl4复合载体负载催化剂。研究了复合载体组成对催化剂的载钛量、形貌以及乙烯聚合行为的影响。当PSA存在时,催化剂的载钛量明显降低。乙烯/1-己烯共聚的反应动力学结果表明,与SiO2/MgCl2.xBu(OH)2/TiCl4相比,无机/有机复合载体负载催化剂的动力学曲线具有一段较长的受扩散控制的诱导期,并且随着PSA质量分数的增加,诱导期延长,动力学曲线由衰减型转变为上升-稳定型。由于复合载体具有多种化学环境,使得负载催化剂活性中心种类增多,共聚性能提高,聚乙烯产品分子量分布变宽,熔流比显著提高。根据聚乙烯树脂的扫描电镜照片,探讨了复合载体负载催化剂在聚乙烯生长过程中的破碎机理。     

无机/有机复合载体负载TiCl_3/(n-BuCp)_2ZrCl_2复合催化剂用于宽峰聚乙烯的制备

采用溶胶-凝胶法,将苯乙烯-丙烯酸(PSA)共聚物包覆在以硅胶/MgCl2为载体的TiCl3催化剂上,负载(n-BuCp)2ZrCl2后制得Ziegler-Natta/茂金属复合催化剂。实验在同一反应釜中进行两段反应模拟双釜串联聚合工艺。在第一段反应中制备高分子量高支化度的乙烯/1-己烯共聚物,在第二段反应中,制备低分子量低支化度的聚合物。淤浆聚合结果表明,所得聚乙烯的熔融流动比(MI21.6/MI2.16)较宽,达到79,分子量分布达到18.6。两段反应得到的聚乙烯共混物的结晶度和熔融温度介于第一段、第二段单独反应时所得产物的结晶度和熔融温度之间,且DSC曲线具有单一的熔融峰,说明该两段反应法制备的聚乙烯共混物具有良好的共结晶行为。动力学研究同时表明,苯乙烯-丙烯酸共聚物的引入,使得催化剂的活性缓慢释放,活性持续时间明显长于负载于无机载体的催化剂,有利于灵活地调节各段反应的停留时间。     

复合载体负载型催化剂制备UHMWPE动力学行为

研究了采用氯化镁和硅胶复合载体负载Mg-Ti型催化剂催化乙烯聚合的性能和动力学行为,考察了聚合温度、时间、压力、助催化剂对催化剂性能的影响,以及链转移反应在其中所起到的作用。结果表明,温度对聚乙烯的相对分子质量影响最大,乙烯分压和聚合温度对催化剂的活性有明显影响,存在一个使催化剂高活性的最适宜铝钛物质的量之比。     

有机/无机复合载体负载复合催化剂生产聚乙烯共混物的共混性质

基于相转化法制备了复合微球载体负载的(n-BuCp)2ZrCl2/PSA/TiCl3复合催化剂。利用聚合物膜将两个传统的催化剂（茂金属和Ziegler-Natta催化剂）隔开,即先将Ziegler-Natta催化剂负载于无机载体上作为内核,随后将聚合物膜均匀沉积在无机载体催化剂表面,最后将茂金属催化剂溶液迅速负载于聚合物膜上,得到“内钛外茂”型(n-BuCp)2ZrCl2/PSA/TiCl3复合催化剂。在实验室条件下,模拟工业淤浆双釜串联反应工艺,在第一段反应中制备超高分子量(1.4×106 g/mol)高支化度的乙烯/1-己烯共聚物,在第二段反应中,制备低分子量低支化度的聚合物。调节两段反应的聚合时间,制备了不同组成的聚乙烯共混物。通过DSC和流变学的方法研究了聚乙烯共混物的共混性能,并与机械共混法得到的聚乙烯共混物的共混性质进行比较。     

MgCl2/SiO2复合载体的活化处理研究

对喷雾法球形MgCl2/SiO2复合载体进行程序升温活化处理,以除去残余的THF溶剂、并保持其规整的球形颗粒形态,对不同升温程序进行对比,最终找到最佳的活化处理方法并得到规整的球形活化复合载体;用活化载体制备负载Ziegler-Natta催化剂,其保持了规整的球形颗粒形态,乙烯聚合实验表明其有较高的聚合活性,聚合产物"复制"了催化剂的球形颗粒形态。     

高效MgCl2/SiO2复合载体型聚乙烯催化剂的研究

采用相同的工艺制备了两种不同的MgCl2/SiO2复合载体型Ziegler-Natta催化剂,考察了SiO2粒径对催化剂的形态结构及其催化乙烯聚合性能的影响,并利用BET测试仪和扫描电子显微镜(SEM)等对催化剂的形态和物性进行了表征。结果表明:加入小颗粒SiO2可以改善催化剂的颗粒形态和均匀程度,而且小颗粒SiO2制备的复合载体催化剂不仅具有较高的催化剂活性,还可使聚合产品的颗粒变得均匀,提高聚合物的堆密度,降低细粉含量,增强氢调敏感性。     

镍二亚胺配合物/复合载体催化剂合成支化PE

研究了在不用甲基铝氧烷.只以通用烷基铝为助催化剂的条件下,以SiO2和MgCl2的复合载体负载3种镍二亚胺配合物催化乙烯进行聚合,庚烷为溶剂制备支化聚乙烯(PE)。结果发现,聚合条件(如配体、载体改性方式、助催化剂、铝/镍、聚合温度和金属镍浓度等)对催化活性有很大的影响。没有经三乙基铝改性的复合载体负载空间位阻最小的镍二亚胺配合物在以-氯二乙基铝为助催化剂、聚合温度14℃、金属镍浓度0.12 mmol/L、铝/镍为80的条件下催化活性达290 kg/mol·h),生成的支化PE的支化度随着聚合温度的升高而迅速增加,受铝/镍的影响不大     

Ziegler-Natta催化剂制备低相对分子质量聚乙烯的研究

采用化学法对MgCl2载体进行改性,负载TiCl4活性组分,制备了Ziegler-Natta催化剂,并用于乙烯聚合制备低相对分子质量聚乙烯.结果表明:乙烯聚合时,同时使用内外给电子体时的聚合活性最高.选用该高效负载催化剂为主催化剂,三乙基铝为助催化剂,温度为100 ℃,压力为1.9 MPa,所制聚乙烯的黏均分子量为(1...     

TiO2-Al2O3复合载体用于加氢脱硫催化剂的性能研究

采用改进的溶胶-凝胶法制备了TiO2-Al2O3复合载体,将不同含量的钛溶胶采用不同方法负载在Al2O3,上制成复合载体,在不同温度下焙烧.用XRD、TEM、BET进行了表征,同时考察以其为载体制成催化剂的加氢脱硫活性.XRD结果表明,复合载体中TiO2和Al2O3分别以锐钛矿和γ-A12O3晶型存在.TEM结果表明,TiO2为纳米粒子且均匀分布在A12O3表面上.复合载体粒子形貌存在差异.以该复合载体所制催化剂在氢分压2 MPa,空速3 h-1,氢油体积比450的条件下,具有较高的加氢脱硫活性,可达98%以上.     

TiCl4 immobilized on a composite support SiO2/MgCl2·x(1,4-butanediol)/poly[styrene-co-(acrylic acid)] for ethylene polymerization: The barrier effect of poly[styrene-co-(acrylic acid)]

By immobilizing titanium-based Ziegler–Natta catalyst on composite support, SiO₂/MgCl₂·x(1,4-butanediol)/poly[styrene-co-(acrylic acid)] (SiO₂/MgCl₂·xBD/PSA) and SiO₂/MgCl₂·xBD/PSA/TiCl₄ (SMPT) were synthesized for ethylene polymerization. SiO₂/MgCl₂·xBD/TiCl₄ without PSA was also prepared for comparison. The results of energy-dispersive X-ray analysis, SEM, and thermogravimetric analysis demonstrated that SMPT had a unique core-mantle-shell structure. The PSA layer can be considered as a barrier for the mass-transfer of reactants based on the results of self-diffusion measurement by pulsed field gradient NMR and ethylene polymerization. The polyethylene produced by SMPT showed high molecular weight (MW) and broad molecular weight distribution (MWD). The influences of PSA content, hydrogen, and comonomer on the ethylene polymerization behavior were also investigated. The results further demonstrated that the PSA layer in the composite support had different diffusion capabilities to the reactants. The physical properties of the produced polyethylene implied the possibility to control the MW and MWD of polyethylene by the manipulation of PSA layer. The catalyst fragmentation during ethylene polymerization was also affected by the PSA shell due to its barrier effect. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Organic/inorganic support for immobilizing (n‐BuCp)2ZrCl2/TiCl3 hybrid catalyst for use in the preparation of polymer blends

Reactor blends of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and low‐molecular‐weight polyethylene (LMWPE) were synthesized by two‐step polymerization using a hybrid catalyst. To prepare the hybrid catalyst, styrene acrylic copolymer (PSA) was first coated onto SiO₂/MgCl₂‐supported TiCl₃; then, (n‐BuCp)₂ZrCl₂ was immobilized onto the exterior PSA. UHMWPE was produced in the first polymerization stage with the presence of 1‐hexene and modified methylaluminoxane (MMAO), and the LMWPE was prepared with the presence of hydrogen and triethylaluminium in the second polymerization stage. The activity of the hybrid catalyst was considerable (6.5 × 10⁶ g PE (mol Zr)^?1 h^?1), and was maintained for longer than 8 h during the two‐step polymerization. The barrier property of PSA to the co‐catalyst was verified using ethylene polymerization experiments. The appearance of a lag phase in the kinetic curve during the first‐stage polymerization implied that the exterior catalyst ((n‐BuCp)₂ZrCl₂) could be activated prior to the interior catalyst (M‐1). Furthermore, the melting temperature, crystallinity, degree of branching, molecular weight and molecular‐weight distribution of polyethylene obtained at various polymerization times showed that the M‐1 catalyst began to be activated by MMAO after 40 min of the reaction. The activation of M‐1 catalyst led to a decrease in the molecular weight of UHMWPE. Finally, the thermal behaviors of polyethylene blends were investigated using differential scanning calorimetry. Copyright © 2011 Society of Chemical Industry     

助剂B对含硅NiMo/Al2O3加氢处理催化剂性能的影响

考察了助剂B对含硅NiMo/Al₂O₃催化剂孔结构及表面酸性的影响，制备出一种孔容和比表面积大、孔分布集中、金属分布均匀和酸性适宜的加氢精制催化剂。分析结果表明，B的加入可以改善含硅氧化铝载体及催化剂的孔结构及表面酸性，有利于C—N键的断裂，从而提高催化剂的加氢脱氮性能。活性评价结果表明，采用适量B助剂改性的加氢处理催化剂具有高的加氢脱氮活性和稳定性。     

选择加氢催化剂载体氧化铝的改性及其工业应用(Ⅱ)

采用浸渍法制备稀土元素和／或碱金属改性的氧化铝加氢催化剂载体,考察了助剂稀土和碱金属的加入对氧化铝热稳定性、表面酸度的影响以及改性载体对活性组分Pd分散度的影响。采用BET法测定催化剂的比表面积,吸附一脱附法测试催化剂的表面物性,在工业装置上进行催化剂应用试验。结果表明,加入改性组分的氧化铝载体制成催化剂,其活性、选择性均有较大提高。     

酸改性CoPd/TiO2催化CH4-CO2直接合成C2含氧化合物

采用酸处理方法对CoPd/TiO₂催化剂进行改性,并将酸改性催化剂用于温和条件下CH₄-CO₂梯阶转化直接合成C₂含氧化合物（乙酸和乙醇）的反应。在150～300℃考察了浸酸方式和不同种类酸处理对催化剂活性和选择性的影响。采用X射线衍射（XRD）、X射线光电子能谱（XPS）、NH₃程序升温脱附（NH₃-TPD）和N₂吸附对催化剂进行了表征。结果表明,酸改性明显提高了CoPd/TiO₂上C₂含氧化合物的生成速率和选择性。浸酸方式对催化剂性能和结构有显著影响,先用酸浸渍载体然后再浸渍活性金属所得催化剂具有更高的活性。在H₃PO₄、HNO₃和HCl中,H₃PO₄浸渍的催化剂活性最佳,在150℃时C₂含氧化合物（乙酸和乙醇）的生成速率为3365 μg/(g·h),选择性达到91%。     

辛醇液相加氢精制催化剂的研究

采用共沉淀法制备了一种新型辛醇液相加氢催化剂。试验研究了助剂铝和不同的载体加入方式对催化剂性能的影响。用压汞法和TPR分别对催化剂的孔结构和还原性能进行了考察，并采用小型加压评价装置对催化剂的加氢活性进行了评价。结果表明，在该催化剂上异辛醛的加氢率达90％，辛烯醇加氢率约80％，加氢产物中辛醇质量分数提高0.5个百分点；Ni/SiO₂系催化剂中加入铝助剂有利于提高加氢活性，加入质量分数以4.5％～6.5％为最佳；催化剂的还原温度应低于600 ℃。     

CO_2 methanation over TiO_2–Al_2O_3 binary oxides supported Ru catalysts

TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.     

Na2CO3/TiO2催化剂的制备及催化性能研究

以钛酸正四丁酯为钛源,采用水热法制备出纯TiO2及Na2CO3修饰的TiO2催化剂样品.以亚甲基蓝溶液模拟染料废水为目标污染物,考察纯TiO2和经Na2CO3修饰后的Na2CO3/TiO2催化剂的催化性能.采用XRD、TEM、BET等方法对催化剂的结构和形貌进行了表征.结果表明,制备出的经Na2CO3修饰后的TiO2催...     

Support Effects on Thiophene Hydrodesulfurization over Co-Mo-Ni/Al2O3 and Co-Mo-Ni/TiO2-Al2O3 Catalysts

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.