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《现代塑料加工应用》2017,(6)
采用邻苯二甲酸酯类为内给电子体,制备了MgCl_2/SiO_2复合载体负载的Ziegler-Natta催化剂,考察了不同聚合条件、MgCl_2和SiO_2质量比、内给电子体结构对复合载体催化剂催化1-丁烯聚合的影响。结果表明,在三乙基铝(AlEt3)为助催化剂、铝钛物质的量比为200、聚合压力为0.10 MPa、聚合温度为30℃、氢气4 mL、聚合时间为2h时,催化剂活性较高,而外给电子体甲基环己基二甲氧基硅烷(CHMMS)加入聚合体系后,催化剂活性下降,但聚合产物等规度提高,当CHMMS与铝的物质的量比为0.033时,聚合产物的等规度最高为95.4%,复合载体催化剂中SiO_2比例增加,活性下降,邻苯二甲酸二异丁酯作为内给电子体更有利于聚丁烯-1等规度的提高。 相似文献
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通过浸渍负载碱式醋酸铬、脉冲流化程序升温焙烧活化法制备了硅胶负载型铬系催化剂(Cr/SiO2),研究了活化温度对催化剂结构及其催化活性的影响。结果表明,随着活化温度升高,催化剂的比表面积和总孔容变化不大,但是平均孔径和Cr(Ⅵ)含量有所下降;硅胶破损程度加剧,但大部分硅胶能保证完整的球状结构,催化剂的聚合活性增加,在700℃活化的催化剂活性最高,达到18.3 gPE·(gcat·h)-1。用脉冲流化法制备的催化剂的聚合活性均随聚合反应时间的增加先快速上升随后迅速降低并趋于一个稳定值。 相似文献
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以SBA-15为载体负载磷钨酸(HPW),用于催化四氢呋喃(THF)开环聚合,采用在线反应红外分析仪(ReactIR)测定THF转化率,实验考察了HPW负载质量百分比、3-氨丙基三乙氧基硅烷(APTES)/SBA-15质量比和载体SBA-15孔径等因素对催化剂的催化性能和THF转化率的影响。结果表明:采用直接浸渍法负载HPW,HPW最优负载质量百分比为40%;将SBA-15进行氨基改性后负载HPW,最优APTES/SBA-15质量比为mAPTES/mSBA-15=0.0712,且通过氨基改性可有效改善催化剂的重复利用性能;当载体SBA-15的比表面积较大时(853 m2·g-1)或孔径较大(比表面积较小498~585 m2·g-1)时,所制备的催化剂具有较高的催化效率、聚合产物平均分子量较大,催化剂的催化效率和聚合产物分子量随着孔径增大而增大。 相似文献
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苯胺基萘醌镍催化剂(Cat.1:4-甲基-2,6-双二苯甲基苯胺萘醌镍配合物、Cat.2:2,6-二异丙基苯胺萘醌镍配合物)可用于乙烯聚合,产物的形态难以控制,易黏釜,限制其工业化应用,因此对该催化剂进行负载化研究,通过将干燥的改性甲基铝氧烷(dMMAO)和一氯二乙基铝(Et_2AlCl)负载于球形纳米级二氧化硅表面,从而使催化剂非均相化。Cat.1-MMAO/SiO_2这类负载型催化剂能引发乙烯均聚,活性高和热稳定性好,在60℃时活性最高,在100℃高温下依旧保持较高的活性(3 600 kg polymer/(mol Ni·h))。随着聚合温度的升高,所得聚乙烯的分子量降低,当反应温度为40℃时,分子量最高(69.4×10~4g/mol),且分子量分布为1.7。该催化体系不仅保留了均相体系活性高稳定性好的特点,还能制备出球形聚合物,具有良好的工业应用前景。 相似文献
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《合成树脂及塑料》2017,(6)
引入硅胶载体,与乙氧基镁在有机混合溶剂中共浸渍得到镁质量分数分别为5.00%,10.00%和15.00%的催化剂前驱体,与TiCl_4反应制得一系列SiO_2/MgCl_2复合载体型Ziegler-Natta催化剂。将所得催化剂用于常压乙烯均聚合、乙烯与1-己烯共聚合和氢调实验,比较不同催化剂活性和产物性能的差异,考察镁负载量对催化剂的影响。结果表明:镁负载量显著影响催化剂的孔结构和组成;镁质量分数为15.00%时,所得催化剂的Ti含量、比表面积以及β-MgCl_2相对含量均较高,其均聚合活性、整体共聚合活性最高,所得聚乙烯具有更高的相对分子质量和更宽的相对分子质量分布;同时,该条件下所得催化剂还具有很好的氢调敏感性。 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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乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。 相似文献
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我厂3号回转窑(Φ4m×60m)生产线在1996年年底由SP窑(产量912t/d)改为NSP窑(产量1320t/d),预分解系统为四级旋风预热器带离线式分解炉 相似文献
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The miscibility of various amorphous polybutadienes with mixed microstructures of 1,4 addition units (cis, 1,4 and trans 1,4) and 1,2 addition units have been investigated. The studies here involved optical transparency, differential scanning calorimetry, and small angle light scattering. It was found that a 90 percent (cis) 1, 4 addition polybutadiene was immiscible with high (91 percent) 1,2 addition polybutadiene. Reduction of the 1,2 content to 71 percent induced an upper critical solution temperature (UCST) with the cis 1,4 polymer. Polybutadienes with 50 percent and 10 percent 1,2 contents were miscible above the crystalline melting temperature of the cis 1,4 polybutadiene. Immiscibility of the 91 percent 1,2 addition polymer was also found with a 10 percent 1,2 polybutadiene. The latter polymer also exhibits an UCST with the 71 percent 1,2 polymer. The results are used to interpret the characteristics of blends of polybutadienes of varying microstructure. 相似文献
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以F类粉煤灰为例,详细介绍了测定粉煤灰中烧失量的步骤、计算数学模型、影响测量不确定度的因素以及各项测量不确定度分量评定,人员、设备、材料、方法、环境都是影响测量不确定的因素。 相似文献
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The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003 相似文献