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酸化膨润土催化合成草酸二丁酯 总被引:4,自引:0,他引:4
以酸化膨润土(SO42-/Bentonite)固体酸为催化剂,草酸和正丁醇为原料,合成草酸二丁酯。考察焙烧温度对催化剂活性的影响。结果表明,焙烧温度500 ℃时催化剂活性较好。考察反应温度、原料配比、催化剂用量和反应时间等因素对酯化反应的影响,通过正交实验得到最佳酯化反应工艺条件:n(正丁醇)∶n(草酸)=3.5∶1,w(SO42-/Bentonite)=1.5%,反应温度130 ℃,反应时间3 h。最佳酯化反应条件下,草酸的转化率达到95.8%。催化剂重复使用6次后,草酸转化率达到93.6%。 相似文献
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硫酸氢钾催化合成乙酸正丁酯 总被引:1,自引:0,他引:1
以硫酸氢钾为催化剂,对以乙酸和正丁醇为原料合成乙酸正乙酯的反应条件进行了研究,研究了酸醇摩尔比、催化剂用量、反应时间、回流温度等因素对酯化率的影响,优化反应条件如下:n(乙醇)∶n(乙酸)∶n(硫酸氢钾)=1∶4∶0.0074;反应时间45min;回流反应温度117 ̄124℃,酯化率可达86.5%。 相似文献
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杂多酸H_3PW_6Mo_6O_(40)超声催化合成乙酸正丁酯 总被引:3,自引:1,他引:2
以磷钨钼杂多酸作催化剂,在超声条件下,以正丁醇和冰醋酸为原料,合成乙酸正丁酯。首先制备了催化剂磷钨钼杂多酸,并对其进行了IR和XRD表征,证明了所制备的磷钨钼杂多酸催化剂具有Keggin的结构。进一步较系统地研究了酯化反应中催化剂焙烧温度、催化剂用量、带水剂种类与用量、醇酸摩尔比、反应时间等对酯化率的影响。结果表明,反应的适宜条件为:在20 kHz,1.0 W/cm2的超声条件下,催化剂焙烧温度为400℃,用量为0.6 g,带水剂为甲苯,用量为10 mL,反应温度为120℃,n(正丁醇)∶n(乙酸)=1.5∶1(乙酸用量为0.4mol),反应时间60 min,酯化率可达99.3%。 相似文献
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以可膨胀石墨为催化剂,柠檬酸和正丁醇为原料,催化合成柠檬酸三丁酯。考察了酸醇摩尔比、催化剂用量和反应时间等因素对柠檬酸酯化率的影响。最佳反应条件为:柠檬酸38.5g(0.2mol),n(柠檬酸)∶n(正丁醇)=1∶4.5,催化剂1.0g,反应时间4.5h,柠檬酸的酯化率达到99.3%。且催化剂可连续使用6次,催化活性无明显降低。 相似文献
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以固体超强酸S2O82-/TiO2为催化剂、冰乙酸和正丁醇为原料合成乙酸正丁酯,考察反应条件对酯化率的影响。结果表明,最佳反应条件n(醇)∶n(酸)=1.4∶1,催化剂用量0.5 g(冰乙酸用量0.2 mol),过硫酸铵浓度0.75 mol.L-1,115~117℃反应1.5 h,酯化率达99%以上。催化剂可重复使用,且对设备腐蚀程度较小。 相似文献
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Properties of two high performance engineering thermoplastics, amorphous polyethersulfone (PES) and semicrystalline polyetheretherketone (PEEK), are discussed. Both resins can be processed by conventional techniques, compounded with high performance fibers, and have high service temperature (up to 300°C). Due to the amorphous character PES can be dissolved and spray coated into metals. 相似文献
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Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively. 相似文献
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This semicrystalline phase, originally named ‘calcium silicate hydrate(II)’ by Taylor (1950), has been studied with X-rays, electron optics, chemical investigation of silicate anion type, infrared spectra, and thermal methods. It is structurally related to jennite (C9S6H11) and probably also to the fibrous CSH of cement pastes, the three phases forming a sequence of decreasing crystallinity. The specimen studied had approximate composition C2SH3.2 after standing over saturated CaCλ2 at about 15°C. CSH(II) contains metasilicate chains and pyrosilicate groups and has a disordered layer structure. Much of the water can be lost reversibly without significant change in lattice parameters. 相似文献
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采用固相合成法制备了(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54(α=0.1~0.5)系陶瓷,表征了该陶瓷的相组成和显微结构,测试了微波介电性能.结果表明:α=0.3时,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷为单相的新钨青铜结构固溶体.α>0.3时,相继出现了第二相BaLa2Ti4O12和La0.66TiO2.993.随α的增加,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷的相对介电常数(εr)先增大后有所波动,品质因数(Qf)先增大后减小,谐振频率温度系数(τf)单调减小.α=0.3时,在1 350℃烧结的陶瓷的微波介电性能最佳:εr=98.77,Qf=5184GHz,τf=10.9×10-6/℃,优于不掺杂的BaO-Sm2O3-TiO2陶瓷的. 相似文献
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Summary In the present work we describe, the synthesis and characterization of a new gel obtained by crosslinking a cooligomer of butadiene-acrylic acid (BuAA), by reaction with acrylonitrile and acrylic acid. The purified product was characterized by FTIR, elemental analyses and scanning electronic microscopy. The thermal properties were studied and swelling indexes were determined in different solvents and at different pH values. The capacity of poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid) [gel A] to separate different organic substances, such as amino acids and colorants, was determined. 相似文献
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Witold Brostow Kwan-Ho Seo Jong B. Beak Jeong C. Lim Kwan-Ho Seo 《Polymer Engineering and Science》1995,35(12):1016-1021
The miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures Tg of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control Tg and melting temperature Tm of PPS by varying amounts of PPSE in blends. The melt crystallization temperature Tmc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE. The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ?2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases. 相似文献
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The addition of side groups to improve the photooxidative stability of polymers used in polymer-based light-emitting diodes (LEDs) is explored. Infrared spectroscopy and computational chemistry techniques are used to study the effects of chemical substitution of the reactive vinylene moiety in poly(phenylene vinylene) (PPV). The bond order of the vinylene group in small oligomers is calculated using semiempirical techniques to assess the improvement in stability toward oxidants such as singlet oxygen. We find that PPV dimers allow relative comparisons across a range of possible substitutions. Experimental results correlate well with these calculations. The addition of electron-withdrawing substituents, such as nitrile groups, to the vinylene moiety is found to be particularly effective in reducing the reactivity of alkoxy-substituted PPV toward singlet oxygen. The photooxidative stability of a poly(phenylene acetylene) (PPA) derivative is also studied. It appears that this family of polymers is more stable toward photooxidation than are its PPV analogs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2451–2458, 1998 相似文献
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Hybrid films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were prepared with different molecular weights of poly(ethylene oxide) (PEO). The cross-linking reaction between PEO and PEDOT:PSS was performed at high temperature and confirmed by using differential scanning calorimeter (DSC), contact angle measurement, and solid-state 1H NMR. The effect of chemical reaction on the conductivity and morphology of these hybrid films was studied by using 4-point probe and atomic force microscope (AFM), respectively. As-spun PEO/PEDOT:PSS films have lower electric conductivity due to the addition of nonconductive PEO, and exhibits no molecular weight dependence on conductivity. After chemical cross-linking reaction at high temperature, only PEDOT:PSS films with lowest molecular weight PEO additives show enhanced conductivity with increasing reaction time. AFM result indicates that the heat-treated PEO/PEDOT:PSS hybrid films show grain-like morphology compared to ethylene glycol treated PEDOT:PSS films which shows continuous PEDOT domain. In the present work we demonstrate that the cross-linking reaction can be used to improve the wet stability of PEDOT:PSS nanofiber, showing good water resistance and excellent dimensional stability. 相似文献