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利用可溶性全氟磺酸树脂和二氧化钛前躯体钛酸丁酯液-液相体系, 结合蒸汽水热结晶方法制备了全氟磺酸树脂/二氧化钛杂化薄膜, 并通过扫描电子显微镜(SEM)、X-射线衍射(XRD)、红外光谱分析仪(FT-IR)及紫外-可见分光光度计(UV-vis)等测试方法对杂化薄膜的形貌、晶型、结构及光学性能进行了表征. 结果表明: 蒸汽水热结晶法能促进全氟磺酸树脂/二氧化钛杂化薄膜的结晶和相变; 水热后该杂化薄膜表面平整光滑, 没有裂纹, 二氧化钛晶型为锐钛矿并以球形微粒均匀分散在全氟磺酸树脂基体中; 随着杂化体系中二氧化钛含量的增多, 其粒径逐渐减小、团聚现象消失且杂化薄膜的紫外吸收性能显著提高. 相似文献
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本文用付立叶变换红外光谱法研究了全氟磺酸树脂中不稳定端基的分解程度与热压成膜温度之间的关系,发现在全氟磺酸树脂的红外光谱中位于1812cm~(-1)处的游离的不稳定羧端基受热分解是造成树脂热压成膜产品中存在大量气泡的主要原因,而且当热压成膜温度增加时,1812cm~(-1)处吸收峰减小,而位于1776cm~(-1)处则产生一个新的吸收峰,两者之间有较好的规律性。同时还发现,树脂在热压成膜过程中存在着两个游离的不稳定端基之间的化合反应。 相似文献
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主要对乙烯-四氟乙烯共聚物(ETFE)、聚全氟乙丙烯(FEP)、聚偏氟乙烯(PVDF)、全氟磺酸树脂(PFSA)和全氟羧酸树脂(PFCR)这几种典型含氟树脂的加工流变行为和线性粘弹性进行了综述。FEP高速挤出时稳定流动区非常窄,并且进行模型拟合时发现其剪切流动行为符合Carreau模型。ETFE为热流变简单高分子,其剪切粘度、拉伸粘度、挤出胀大和动态模量等流变函数均可进行时温叠加。在低剪切速率下,PVDF熔体表现出牛顿流体行为;在高剪切速率下,PVDF熔体呈现出剪切稀化现象。PFSA和PFCR熔体的表观黏度随剪切速率、温度的升高而降低,流动曲线显示该熔体属于假塑性流体。 相似文献
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全氟辛基磺酸稀土金属盐催化氟两相Friedel-Crafts酰化反应;氟两相催化;全氟辛基磺酸稀土金属盐;全氟溶剂;Friedel-Crafts酰化 相似文献
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全氟辛基磺酸稀土金属盐催化氟两相Friedel-Crafts烷基化反应;氟两相催化;全氟辛基磺酸稀土金属盐;全氟溶剂;Friedel-Crafts烷基化 相似文献
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《Comptes Rendus Chimie》2016,19(10):1247-1253
High surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol–gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719 m2/g) mesoporous (pore size 67 Å and pore volume 1.19 cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol–gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Brønsted acidity. These catalysts showed very high catalytic activity for esterification; a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost. 相似文献
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Concentrated homogeneous mineral acids have been widely used as catalysts in industrial processes for several decades. These catalysts are corrosive to the apparatus, and there are large volumes of chemically reactive waste stream that are difficult to deal with[1]. In order to solve these problems, investigators have replaced these mineral acids with solid acid catalysts. Besides inorganic solid acid catalysts such as zeolite, solid organic polymeric resins containing acid groups, especially sulfuric acid resins such as Amberlyst[2], have attracted much attention. Compared with most inorganic acid catalysts, they have the advantages of their potentially high acidity, controllable surface area and porosity[3]. This article reports a novel sulfonated poly(phthalazinone ether sulfone ketone) (S-PPESK) resin and its application to isobutene oligomerization. S-PPESK exhibits high catalytic activity and excellent dimerization selectivity. 相似文献
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ecent advances in liquid-phase organic reactions over solid acids are described based on the catalyses of acidic clays and silica-included heteropoly compounds. Zinc ion-exchanged smectite clays, particularly nontronite clays, were effectively applied as insoluble, readily recoverable solid acid catalysts to liquid-phase Friedel-Crafts reactions. Montmorillonite K10 catalyzes the synthesis of alkylporphyrin derivatives from aliphatic aldehydes and pyrroles more efficiently than the conventional homogeneous acids such as BF3 etherate. 12-Tungstophosphoric acid and its acidic Cs salt could be included in a silica matrix by means of sol-gel technique involving hydrolysis of ethyl orthosilicate forming insoluble and easily separable solid acid catalysts. These silica-included heteropoly compounds were thermally more stable than an ion-exchange resin catalyst such as Amberlyst-15, and catalyzed the hydrolysis of ethyl acetate in the liquid phase more efficiently than the resin, H-ZSM-5 and even than aqueous heteropolyacid. 相似文献
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以乙醇和乙酸的酯化作为反应模型,考察固体酸催化剂阳离子交换树脂、SO42-/ZrO2和分子筛在微波加热条件下的酯化活性。结果表明,三类固体酸催化剂的活性顺序为Amberlite树脂﹥SO42-/ZrO2﹥HZSM-5,催化剂活性与酸度一致;酯化反应中水的含量对催化剂的活性有不同程度的影响,水含量较高时催化剂SO42-/ZrO2酯化活性明显变差,而阳离子交换树脂仍具有较高的酯化活性。采用阳离子交换树脂对生物油进行微波催化酯化提质后,原生物油中含有的大量不同种类的羧酸被有效地转化成各种酯类,酯类化合物由原油中的4种增加到13种。与传统加热条件下生物油催化提质比较,生物油微波提质具有明显优势,提质后生物油组分得到优化。 相似文献
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表面含磷酸的介孔分子筛P-SBA-15的合成及其性能评价 总被引:4,自引:1,他引:4
采用后合成法,将磷酸固载在纯硅介孔分子筛SBA-15表面上。利用X射线衍射(XRD)、红外光谱(IR)、氮气吸附 脱咐法(BET)分析方法表征催化剂的物理性能。结果表明,催化剂P-SBA-15在高温焙烧后保持了稳定的介孔分子筛SBA-15结构,该催化剂的比表面积和孔径分别为605.45m2/g和5.576nm(磷硅摩尔比5%)。选用十一碳烯酸与异丙醇的酯化反应对催化剂P-SBA-15的催化反应性能进行评价,同时与其他几种微孔沸石分子筛催化剂催化性能相比表明,磷酸改性的介孔分子筛P SBA 15是合成十一烯酸异丙酯较为理想的固体酸催化剂,考察了催化剂的稳定性。 相似文献
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酸碱性硅溶胶对浆状Cu/Zn/Al催化剂性能的影响 《燃料化学学报》2015,43(10):1221-1229
在完全液相法研究发现的基础上,选用酸、碱性硅溶胶,制备Cu/Zn/Al/Si浆状催化剂,采用X射线衍射(XRD)、氢气程序升温还原(H2-TPR)、红外光谱分析(FT-IR)、氮气吸附、氨气程序升温脱附(NH3-TPD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)等对催化剂进行了表征。结果表明,两类硅溶胶引入Cu/Zn/Al催化体系后,与前驱体制备环境一致的酸性硅溶胶能显著提高催化剂的CO的转化率和二甲醚的选择性,最高分别可达65.38%和76.26%。酸性硅溶胶削弱了Cu与其他组分的相互作用力,催化剂表现为易于还原、晶粒度大,暴露出丰富的反应所需的Cu0活性晶面。此外,硅溶胶的酸碱性质还改变催化剂酸中心的强度和数量且使强、弱酸中心均向低温方向迁移,酸性硅胶制备的催化剂中弱酸中心数量多,进而提高了催化剂活性和二甲醚的选择性。大比表面积和介孔孔隙丰富的催化剂孔结构亦有利于催化剂活性和二甲醚选择性的提高。 相似文献
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New magnetically recoverable solid acid catalysts for acid‐catalyzed reactions were designed via the surface chemical functionalization of silica‐coated magnetite nanoparticles (SCMNPs) with sulfonic acid groups. First, the SCMNPs were covalently functionalized with 3‐aminopropyl groups to achieve Amp‐SCMNPs. Then, reaction of the Amp‐SCMNPs with 1,4‐butane sultone followed by acidification with phosphotungstic acid (HPW) or diluted sulfuric acid produced magnetically recoverable solid acid catalysts, HPW‐ampsul‐SCMNPs and H‐ampsul‐SCMNPs, respectively. Both catalysts were characterized by various physicochemical analyses such as Fourier transform infrared (FT‐IR) and inductively coupled plasma‐optical emission (ICP‐OES) spectroscopies, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and energy‐dispersive X‐ray (EDX) analyses. Finally, the catalytic activities of the prepared catalysts were examined in the esterification of acetic acid with butanol and acetalization of benzaldehyde with ethylene glycol. Excellent catalytic efficiencies were obtained in both cases. The catalysts were consecutively recovered and reused five times without significant loss of their activities. 相似文献
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Fluorous reverse-phase silica gel (FRPSG)-supported Lewis acids which have fluorous ligands acted as effective catalysts of Baeyer-Villiger and Diels-Alder reactions in water. Direct esterification of carboxylic acid with alcohol in organic media was also catalyzed. The FRPSG-supported Lewis acids could be recycled by simple filtration after the reaction. 相似文献
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磁性二氧化硅微球的表面修饰及其在植物基因组核酸纯化中的应用 总被引:3,自引:3,他引:0
在利用自主研发的专利技术制备球形磁性硅胶微球的基础上,对磁性硅胶微球进行表面改性,使其表面分别键合硅羟基、环氧基、邻二醇基和羧基等官能团,并对表面官能团进行了定量研究。以小牛胸腺基因组脱氧核糖核酸(DNA)为模型化合物,研究了核酸在不同表面官能团的磁性硅胶上的吸附和脱附行为,发现表面具有硅醇基的磁球对DNA的回收率最高。将改性后磁性微球应用于玉米DNA的提取,得到了平均长度大于8kb的高纯度基因组DNA。与传统的有机溶剂抽提法相比,基于磁性微球的核酸固相萃取法具有快速简便、省时省力、易于自动化的特点,适合于大规模植物基因组DNA的样品制备。 相似文献