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Dehydration of Ethanol into Ethylene over Solid Acid Catalysts 总被引:8,自引:0,他引:8
The dehydration of ethanol into ethylene was investigated over various solid acid catalysts, such as zeolites and silica–alumina,
at temperatures ranging 453–573 K under atmospheric pressure. Ethylene was produced via diethyl ether during the dehydration
process. H-mordenites were the most active for the dehydration. It was suggested that the catalyst activity could be correlated
with the number of strong Br?nsted acid sites in the catalyst. Further, the H-mordenite was more stable with a SiO2/Al2O3 ratio of 90 than with a SiO2/Al2O3 ratio of 20. 相似文献
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综述了各种聚氨酯用改性聚醚多元醇 ,包括聚合物多元醇、聚脲多元醇、聚合多元醇和不饱和聚酯多元醇等 ,重点介绍了应用比较广泛的聚合物多元醇和聚脲多元醇。 相似文献
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以环氧丙烷(PO)为原料,三(2-羟乙基)异氰脲酸酯(THEIC)为起始剂,采用实验室自制的双金属氰化配合物(DMc)为催化剂,合成具有类似于异氰酸酯三聚结构、本身具有可膨胀阻燃结构的异氰脲酸聚醚多元醇。考察了温度/压力与时间的关系,研究了原料中的水分、聚合温度及催化剂对聚合反应的影响。结果表明:诱导期中温度和压力均随时间的延长而升高;聚合期中压力和温度较为恒定,物料完全反应后釜内压力接近于0;水分在聚合反应体系中的阻聚作用是异常明显的;在温度为135℃,催化剂的质量分数为440×10^-6的条件下,催化剂的催化效率和产率最高,诱导期和反应时间缩短。 相似文献
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以可再生资源蓖麻油制备的蓖麻油甲酯、己二酸、乙二醇为原料,钛酸四正丁酯为催化剂,经酯化、缩聚合成蓖麻油酸基聚酯多元醇,考察了反应时间、催化剂、蓖麻油甲酯对聚酯多元醇热稳定性能的影响,采用凝胶色谱(GPC)、红外光谱仪(IR)、示差扫描量热仪(DSC)对蓖麻油酸基聚酯多元醇的相对分子质量、结构、热稳定性进行了系统的表征。实验表明,在醇酸(己二酸∶乙二醇)比为1.15、催化剂质量分数0.04%~0.05%、温度180℃,真空缩聚2h的条件下,制得相对分子质量为2600~3800、分布指数(PDI)为1.89~2.44的不同蓖麻油酸含量的聚酯多元醇,蓖麻油酸基聚酯多元醇的熔点随着蓖麻油酸含量的增加而降低。 相似文献
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丙烯酸及其酯应用广泛,全球需求量日益增加。目前,丙烯酸的制备主要靠丙烯部分氧化法,对不可再生资源石油高度依赖,而石油资源日渐短缺与丙烯酸需求快速增长产生矛盾不可避免。寻求一条可持续的绿色发展路线合成丙烯酸及其酯迫在眉睫,乳酸及其低碳醇脱水法就是丙烯酸及其酯制备的理想方法。文章对乳酸及其低碳醇酯脱水制备丙烯酸及其酯的催化剂及工艺条件进行了较为系统的总结,特别是对近十年的研究进展的总结。以二氧化硅负载的磷酸盐、硫酸盐催化剂研究较多,活性较高;以改性后的分子筛譬如Y型分子筛具有非常高的反应活性和丙烯酸及其酯的选择性。另外,锂皂石、膨润土的良好催化性能也值得关注。 相似文献
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以三羟乙基异氰脲酸酯为起始剂,双金属氰化物DMC为催化剂,催化缩水甘油和环氧丙烷(PO)合成超支化聚醚多元醇,并用马来酸酐(MA)对其改性制备不饱和超支化聚醚酯多元醇。讨论了PO与MA的摩尔比对聚合反应的影响,并使用红外光谱和核磁共振图谱对产物结构进行表征。结果表明:适量的聚合单体MA的引入可以提高聚合反应速率,缩短聚合反应时间。当PO与MA的摩尔比为45∶1时,聚合反应时间最短,单体转化率最高。 相似文献
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利用松香改性多元酸马来海松酸合成了马来海松酸聚酯多元醇(MAPP),考察了制备MAPP过程中的诸多影响因素,包括催化剂种类和用量、常压下反应时间、二元醇的种类、反应温度以及醇酸的物质的量比、减压反应时间等,并对制备产品的相对分子质量进行了高效凝胶色谱(GPC)表征。最终得出制备高性能MAPP的最优方案,即反应物在常压下于220℃反应4 h,催化剂选择0.10%(质量分数)氧化锌、在减压下反应3 h、n(二甘醇)∶n(马来海松酸)为1.20。利用所研制的MAPP制备的水性聚氨酯(WPU)具有更高的硬度、更强的拉伸强度和更好的耐水性。 相似文献
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聚醚多元醇羟值测定方法的改进 总被引:3,自引:0,他引:3
通过对聚醚多元醇羟值测定方法的改进,使聚醚多元醇中的羟值测定时间由原来的2h缩短为30min。改进后的方法具有简单、快速、准确等优点。 相似文献
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The influence of the acid treatment on cyclohexanone selectivity of phenol hydrogenation over Pd on active carbon was studied in liquid phase reaction and by temperature-programmed desorption. Acid treatment of activated carbon led to an increased cyclohexanone/cyclohexanol ratio. Acid modification of the carbon support enriched the electron density of Pd, and enhanced the desorption of the phenoxy species, which resulted in improved cyclohexanone selectivity in phenol hydrogenation. 相似文献
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磷腈类催化剂及其在聚醚多元醇合成中的应用 总被引:2,自引:0,他引:2
详细描述了磷腈类催化剂的合成方法及其在聚醚多元醇生产中的应用,同时介绍了该类催化剂的脱除与回收方法。采用承载的磷腈类催化剂不仅可简化生产聚醚的后处理工艺,而且能有效地降低其生产成本。 相似文献
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The highly active Pd/C catalysts for formic acid electrooxidation have been prepared by a modified polyol process at different pH values of reaction solutions and different reducing temperatures, respectively. Their physical properties have been characterised by energy dispersive analysis of X‐ray, X‐ray diffraction and transmission electron microscopy. Their electrochemical performances for formic acid electrooxidation have been tested by cyclic voltammetry and amperometric i–t curves. The results of physical characterisations show that all the Pd/C catalysts present an excellent face centered cubic crystalline structure. Their particle sizes are decreasing firstly and then increasing with the increasing of the pH values of reaction solutions. The reducing temperatures also markedly affect the Pd particle sizes. And their nanoparticles have narrow size distributions and are highly dispersed on the surface of carbon support, and Pd metal loading in Pd/C catalyst is similar to the theoretical value of 20 wt.%. The results of electrochemical measurements present that the Pd/C catalyst prepared by waterless polyol process at the pH value of 10 and the reducing temperature of 120 °C has the smallest particle size of about 5.6 nm, and exhibits the highest catalytic activity (1172.0 A · gPd<?h‐2.85>–1<?h.8>) and stability for formic acid electrooxidation. 相似文献
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Narendra Kumar Marina Lindblad Jaana Makkonen Väinö Sippola Heidi Österholm Marja Tiitta 《化学,工程师,技术》2021,93(6):974-980
Catalytic dimerization of 1-hexadecene is shown to be a promising path to make high quality base oil. The base oil is produced by hexadecene dimerization with acid mesoporous silica-alumina catalyst, followed by distillation and hydrogenation. The base oil stock had a high viscosity index (typically 140–150) and a low volatility (Noack typically less than 8 %). The best performance in hexadecene dimerization was achieved with the MCM-22 zeolite embedded MCM-41 catalyst within the silica-alumina catalysts compared. Commercial mesoporous silica-alumina catalysts behaved similarly to a non-commercial MCM-41 catalyst. Y-zeolite and ion exchange resin Amberlyst-35 deactivated fast. 相似文献
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硅氧烷接枝改性ABS 总被引:1,自引:0,他引:1
以过氧化苯甲酰为引发剂,用溶液接枝共聚法将甲基丙烯酰氧基丙基三甲氧基硅烷(MPTMS)接枝到丙烯腈-丁二烯-苯乙烯三元共聚物(ABS)上。用红外光谱对产物进行表征,采用热重分析仪、氧指数仪、锥形量热仪和万能电子拉力机测试产物的热性能、燃烧性能和力学性能。结果屁示,接枝后材料的氧指数提高了2.6%,点燃时间从28s延长到36s.热释放速率降低40%,总烟释放量从4300m^3降至3167m^3,表明MPTMS已被接枝到ABS上.可提高ABS的阻燃性。接枝ABS的拉伸强度有较大提高,冲击强度有所下降,但影响较小。 相似文献
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高选择性乙醇脱水制乙烯催化剂的研制 总被引:1,自引:0,他引:1
徐菁 《化学反应工程与工艺》2011,27(1):64-67
采用在氧化铝中引入氧化硅组份和水蒸汽处理手段来提高乙醇脱水制乙烯催化剂的酸量,从而达到提高乙烯选择性的目的.考察了氧化硅含量和水蒸汽处理条件对催化剂活性和稳定性的影响.结果表明,氧化硅含量是催化剂选择性和稳定性兼顾的关键,适当水蒸汽处理有利于提高催化剂的选择性.以20%氧化硅含量制得的氧化硅-氧化铝复合催化剂,再在55... 相似文献