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随着纳米科技的飞速发展,合成纳米材料的新方法层出不穷。由于在纳米材料合成中的特殊效应,超声化学法用于制备特殊功能的纳米材料引起了材料科学界的极大关注,并取得了显著的进展。本文介绍了超声化学法制备纳米材料的原理和合成形态的控制纳米材料。 相似文献
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ZnO粉是用于传感器、压敏电阻、颜料、电子记录器、医用等的重要材料.ZnO粉的制备方法有多种,如溶胶-凝胶法,溶体蒸发分解法、湿化学合成法、气相反应法等.其中水热合成法是比较理想的方法,这种方法广泛用于优质氧化物粉的合成.然而,采用传统的水热法是难以合成ZnO纳米粉的. 相似文献
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目前,用合成共聚物和树脂制活性炭已成为普遍研究的课题。这种炭材料没有杂质,而且通过对原材料选择和处理的方法可控制其元素组成和孔结构。由于合成炭具有许多独特的优点,故被用于最危急的情况下,如在医学上用于碱液的吸附解毒。 相似文献
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氟络钛酸钾〔K2(TiF6)〕可用于改善牙科材料的性能。通过合成技术的改进,使合成反应时间大大缩短,合成技术更为安全可靠。文中介绍的改进方法成本低廉、工艺简单、易于操作,具有较好的实用性及推广价值。 相似文献
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The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst 相似文献
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Mesoporous titania (TiO(2)) was synthesized by hydrothermal method using cetyltrimethyl ammonium bromide (CTAB) as a template and using anhydrous ethanol and tetra-n-butyl titanate (TBOT) as raw materials. Mesoporous titania solid superacid and nanosized titania solid superacid catalysts were prepared by wet impregnation method. The structure and property of as-prepared samples were characterized by means of XRD, FT-IR and N(2) physical adsorption. The esterification of salicylic acid with isoamyl alcohol and the condensation of cyclohexanone with ethylene were used as model reactions to test the catalytic activities of the catalysts. On the other hand, the comparison of catalytic activities of the prepared solid superacid catalysts and the conventional liquid acid H(2)SO(4) was also carried out under the same experimental conditions. The results show that the catalytic activities of the prepared solid superacid catalysts were higher than that of the conventional liquid acid H(2)SO(4), and that the catalytic activity of mesoporous TiO(2) solid superacid is the highest among the three catalysts. Mesoporous TiO(2) solid superacid is a good catalyst for the synthesis of isoamyl salicylate or cyclohexanone ethylene ketal. 相似文献
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A magnetic SO42−/ZrO2–B2O3–Fe3O4 solid superacid catalyst is prepared via a simple chemical co-precipitation approach. The obtained materials were characterized in detailed by X-ray powder diffraction, thermogravimetric analysis–different scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), electron microscopy (SEM and TEM), and Mossbauer spectra. Powder X-ray diffraction patterns show that in this composite oxide the transformation temperature of ZrO2 from tetragonal to monoclinic phase is higher compared to the pristine SO42−/ZrO2 material. The introduction of Fe3O4 endows the superacid with a super-paramagnetic property while in a ferromagnetic state after calcination. The superacid exhibits high catalytic activity in forming ethyl acetate by esterification. 相似文献
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采用溶胶-凝胶法和浸渍法制备了系列SO_4~(2-)/TiO_2-Al_2O_3固体超强酸催化剂,运用XRD、NH_3-TPD、FT-IR、PyFTIR、XPS、SEM等技术手段,研究了复合催化剂材料的结构与性质,初步探讨了固体超强酸SO_4~(2-)/TiO_2-Al_2O_3催化剂的构效关系,得到适宜的催化剂制备条件为:n(TiO_2)/n(Al_2O_3)=1∶2、硫酸浸渍浓度1mol/L、催化剂焙烧温度500℃。考察了物料物质的量比、催化剂用量、反应时间等对催化合成冰片的影响。结果表明,在物料物质的量比为1∶0.4,催化剂用量为α-蒎烯质量的7%,采用程序升温方式(65℃-1h,75℃-4h,90℃-1h)加热的条件下,固体超强酸SO_4~(2-)/TiO_2-Al_2O_3催化剂的催化活性最高,α-蒎烯的转化率高达100%,龙脑的收率高达59.74%,SO_4~(2-)/TiO_2-Al_2O_3固体超强酸催化剂在重复使用6次的条件下,α-蒎烯的转化率均不变,龙脑的收率下降2.99%,催化剂的重复使用性良好。 相似文献
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催化乳酸铵酯化的改性树脂的制备与表征 总被引:1,自引:0,他引:1
为降低酯化催化剂的制备成本,提高催化酯化反应的性能,以磺酸型阳离子交换树脂和FeCl3·6H2O为原料,采用液固溶剂法制备了固体酸催化剂.利用XRF,FTIR,XRD,NH3-FTIR对催化剂进行表面酸性、元素含量等性质的测试表征.研究表明,FeCl3与阳离子交换树脂的Bronsted酸中心(SO3H)发生化学反应形成了新的Lewis酸中心,络合到树脂上的Fe3+量为11.8%.测试了催化剂促进乳酸铵和正丁醇酯化反应的催化活性,当催化剂用量为1.5%时,酯化率高达96.1%. 相似文献
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竹炭基固体酸催化剂的制备及其催化性能研究 总被引:3,自引:0,他引:3
以4年生慈竹为炭源制备新型碳基固体强酸催化剂,以油酸与甲醇的酯化反应为模型反应主要考察了炭化温度、炭化时间、磺化温度和磺化时间等因素对其催化剂性能的影响。研究结果表明,以竹子作为碳源,利用硫酸合成碳基固体酸催化剂的最佳工艺条件为:碳化温度650℃,碳化时间6h,磺化温度140℃和磺化时间10h,在此条件下油酸与甲醇的酯化反应的转化率达到94.70%。竹炭基固体酸催化剂制备简单,催化酯化反应条件温和,克服了传统液体酸催化剂的缺点,具有良好的稳定性,且通过简单的过滤即可回收重复利用具有很好的应用前景。 相似文献
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A series of composite solid superacid catalysts SO(4)(2-)/ZrO(2)-M(x)O(y) (M=Ti, Ni, Si) were prepared and investigated by means of Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). All catalysts exhibit good catalytic activity in the electrochemical reaction of p-xylene with methanol assisted with a pair of porous graphite plane electrodes and the selectivity of main products higher than 90% were observed. In particular, SO(4)(2-)/ZrO(2)-SiO(2) catalyst exhibited excellent catalytic activity. According to the experimental results, a possible free radical reaction mechanism confirmed by XPS and ultraviolet-visible (UV-vis) spectra was proposed. It may be concluded that a simple and feasible electrochemical catalytic oxidation reaction at room temperature and standard atmosphere may be possible. 相似文献