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采用无机钛硅原料合成了钛硅分子筛TS-1,经酸处理后对合成的钛硅分子筛TS-1进行二次晶化修饰改性.用X射线衍射仪(XRD)、傅立叶红外光谱(FT-IR)和扫描电子显微镜(SEM)对二次晶化后的钛硅分子筛进行表征,发现晶粒变小,钛进入了分子筛的骨架中.考察了二次晶化后的催化剂对环己酮氨氧化反应的催化性能.结果表明,二次晶化法可提高TS-1分子筛的催化性能,在氨、环己酮和过氧化氢的物质的量之比为2.0∶1.0∶1.5、催化剂用量为18 g/mol和75 ℃的条件下,反应4 h后,过氧化氢的转化率、环己酮的转化率和环己酮肟的收率分别为98.12%,97.07%和93.33%. 相似文献
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以钛硅分子筛TS-2为催化剂,过氧化氢为氧化剂,甲醇为溶剂,研究TS-2催化剂催化丙烯生成环氧丙烷.考察了停留时间、反应温度、反应压力和催化剂用量对环氧丙烷收率和选择性的影响.实验结果表明,合适的反应条件为50℃,0.30 MPa,催化剂用量为反应物质量的3.44%,停留时间90 min.在该条件下反应,过氧化氢的平均转化率和环氧丙烷的选择性分别为45%和96%左右.TS-2催化剂的重复使用实验表明,TS-2催化剂在催化丙烯环氧化制环氧丙烷的反应中具有较好的催化活性和稳定性. 相似文献
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分别以硅溶胶和三氯化钛(TiCl_3)作为硅源与钛源、以四丙基溴化胺(TPABr)为模板剂,制备了一系列低成本的大颗粒钛硅分子筛(TS-1)。使用XRD,FTIR,UV-vis,SEM,N_2吸附-脱附等技术对催化剂进行表征,研究了结晶温度和碱度对TS-1的结构与催化性能的影响。评估了催化剂对于环己烷氧化制备KA油(环己醇和环己酮)的催化活性,考察了不同氧化剂用量和催化剂用量下KA油的产率。结果表明:以TS-1-5为催化剂,在最佳反应条件下KA油的产率达到了23.0%,选择性为97.8%,催化剂在重复使用4次后的活性与结构没有发生明显变化。这种大颗粒的TS-1可以在10 min内通过自然沉降从反应体系中分离,而传统钛硅分子筛至少需要5 h。 相似文献
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以无机钛硅为原料、四丙基溴化铵(TPABr)为模板剂、乙胺水溶液为碱源的TPABr-乙胺体系合成钛硅分子筛TS-1,研究了碱用量对TS-1分子筛结晶和催化性能的影响。利用FT-IR、XRD、UV-Vis和SEM等对TS-1分子筛的结晶情况进行了表征。以催化烯丙醇环氧化为探针反应,研究碱用量对TS-1分子筛催化性能的影响。在硅源、碱源摩尔比1∶1.9与1∶0.25之间调节碱加入量,结果表明,TPABr-乙胺体系法合成的样品,具有典型的MFI特征结构。合成出的TS-1分子筛晶体呈长方体形,长度约为4.4~8.8μm。碱用量减少得到的TS-1催化剂样品的相对结晶度低;当碱用量降低至0.25时,得到无定形态粉末;碱用量增多合成的TS-1分子筛样品相对结晶度高,非骨架钛物种和锐钛矿含量减少,晶粒的尺寸缩小,催化丙烯醇氧化产物的选择性显著提高,达到98%。 相似文献
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采用四丙基氢氧化铵(TPAOH)溶液对未焙烧钛硅分子筛TS-1(TS-1-B)进行二次晶化改性,以尿素为沉淀剂通过沉积-沉淀法制备改性和非改性的TS-1-B固载Au纳米催化剂,对比研究这两种催化剂丙烯氢氧环氧化反应性能的差异,阐明二次晶化改性对TS-1-B表面结构及催化行为的影响。结果表明:二次晶化改性提高了TS-1-B结晶度,降低了缺陷位硅羟基数量;改性的TS-1-B表面疏水性的提高有助于抑制产物环氧丙烷(PO)在羟基位点上吸附,其固载的金催化剂表现出显著提高的稳定性和活性。此外,对该催化剂的动力学行为也进行了研究,并计算了主/副产物生成活化能。 相似文献
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《化学与生物工程》2016,(8)
以正硅酸乙酯为硅源、钛酸丁酯为钛源、四丙基氢氧化铵(TPAOH)为模板剂,采用二次晶化法在TPAOH/SiO_2=0.1时合成不同硅钛比的TS-1分子筛,通过XRD、FTIR、UV-Vis、SEM等对TS-1分子筛的结构和形貌进行表征,并以苯酚羟基化反应为探针反应考察其催化性能。结果表明,胶液中硅钛比相同时,二次晶化法合成的TS-1分子筛骨架钛含量高于传统方法,且随着胶液中钛含量的增加,骨架钛含量呈增加趋势;当硅钛比为20时,骨架钛含量达到饱和,多余钛原子以锐钛矿形式聚集;TS-1分子筛粒径较小,为200~300nm。由于骨架钛含量高、粒径小,TS-1分子筛在苯酚羟基化反应中表现出较好的催化性能,当硅钛比为20时,苯酚转化率达到最高,为27.30%。 相似文献
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采用水热合成法制备Ce修饰介孔磷酸铝,再通过原位还原法负载纳米Au-Pd制备催化剂;通过以空气为氧化剂的环己烷选择性氧化反应测试催化剂的催化性能,并考察水热温度、Ce掺杂量、负载贵金属对催化剂催化氧化环己烷的的影响。结果表明,以140℃水热制备的Ce掺杂质量分数为0. 15%的Ce0. 15-APO(140)负载Au-Pd双金属(Au与Pd质量比3∶1)催化剂活性最高。在反应温度120℃,空气压力1 MPa和反应1 h的条件下,环己醇+酮的产率可达11. 81%,选择性达99%,催化剂在同样条件下循环使用5次,活性无明显下降。 相似文献
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Fang Yao Lixin Xu Jili Luo Xiao Li Yue An Chao Wan 《Korean Journal of Chemical Engineering》2018,35(4):853-858
A variety of TiO2@SBA-15 supporters with various TiO2 loadings were synthesized using a facile sol-gel method. Gold (Au)-based catalysts were prepared with an environmentally benign and economical bioreduction method via Cacumen Platycladi (CP) leaf extract and immobilized on various TiO2@SBA-15 supporters with different TiO2 loadings. The as-prepared biosynthesized Au catalysts were applied in the liquid-phase cyclohexane oxidation. The results showed that the Au nanoparticles were well-dispersed on TiO2@SBA-15, and the Au existed as Au0. These biosynthesized Au catalysts are promising for cyclohexane oxidation, achieving a turnover frequency up to 3,426 h?1 with a 14.1% cyclohexane conversion rate. 相似文献
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《Catalysis communications》2007,8(3):247-250
Four microporous materials, zeolites HZSM-5, Y, Beta and TS-1, were used as the supports to prepare supported gold catalysts using impregnation or deposition precipitation. The gold catalysts were tested in the direct synthesis of hydrogen peroxide from H2 and O2 and for CO oxidation. The effect on the catalytic activity of different metal (e.g., Pd, Pt, Cu, Ag, Rh or Ru) on the synthesis of hydrogen peroxide was also tested. Organic substrates, such as cyclohexane or cyclooctene, were introduced to investigate the possibility of in situ H2O2 oxidation with these catalysts. 相似文献
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《Catalysis communications》2009,10(15):2485-2488
TS-1 (titanium silicalite-1) catalysts were hydrothermally synthesized in the presence of polymethylmethacrylate bead (denoted as TS-1_PMMA) and polystyrene bead (denoted as TS-1_PS) for use in the direct epoxidation of propylene with hydrogen peroxide. TS-1 catalyst was also synthesized by a hydrothermal method in the absence of polymer bead. It was revealed that TS-1_PMMA and TS-1_PS catalysts showed a better catalytic performance than TS-1 catalyst in terms of conversion of hydrogen peroxide, selectivity for propylene oxide, and yield for propylene oxide, due to their enhanced hydrophobicity. Among three catalysts, TS-1_PS with the highest hydrophobicity showed the best catalytic performance. 相似文献
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Graham J. Hutchings Silvio Carrettin Philip Landon Jennifer K. Edwards Dan Enache David W. Knight Yi-Jin Xu Albert F. Carley 《Topics in Catalysis》2006,38(4):223-230
Selective oxidation is of key importance in the synthesis of chemical intermediates. For many years a number of oxides and
supported metal catalysts have been used. The key questions involved in the design of selective oxidation catalysts are discussed
in the initial part of this paper. One of the most exciting recent developments in the field of selective oxidation has been
the discovery that supported gold catalysts are active. The second part of the paper discusses Au/C catalysts, which are shown
to be particularly versatile for oxidation reactions. Four examples of selective oxidation are described using molecular oxygen
as oxidant: (a) selective oxidation of glycerol to glycerate in the presence of base; (b) the oxidation of cyclohexane to
cyclohexanol and cyclohexanane in the presence of a radical initiator; (c) the oxidation of hydrogen to hydrogen peroxide,
and (d) the oxidation of benzyl alcohol to benzaldehyde under solvent free conditions. In contrast, the Au/C catalysts are
not active for oxidation of carbon monoxide at ambient temperature. These examples demonstrate that there exists a rich potential
for Au/C as a selective oxidation catalyst and that research efforts should now be focussed on selective oxidation using supported
gold catalysts. 相似文献
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Hong Zhao Jicheng Zhou Hean Luo Chuyi Zeng Dehua Li Yuejin Liu 《Catalysis Letters》2006,108(1-2):49-54
Nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method. The prepared
sample was characterized by XRD, TEM, and N2 sorption. The results showed that the sample of Ag/MCM-41 had no appreciable incorporation of silver into the mesoporous
matrix of MCM-41 with good crystallinity, and silver nanoparticles were dispersed inside or outside of the channels in the
mesoporous host. The catalytic performance of the sample for the cyclohexane liquid-phase oxidation into cyclohexanone and
cyclohexanol by oxygen in the absence of solvents without inducing agents was investigated. The 83.4% selectivity to cyclohexanol
and cyclohexanone at 10.7% conversion of cyclohexane was obtained over Ag/MCM-41 catalyst at 428 K for 3 h. The turn over
numbers (TONs) of Ag/MCM-41 was up to 2946. The catalytic activity of Ag/MCM-41 was also compared with Ag/TS-1 as well as
Ag/Al2O3. The results indicated that Ag/MCM-41 showed superior activity to both Ag/TS-1 and Ag/Al2O3. A calcined Ag/MCM-41 was found to be an efficient catalyst for the cyclohexane oxidation into cyclohexanol and cyclohexanone
using oxygen as oxidant. 相似文献
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钛硅分子筛TS-1的合成改性及其催化功能 总被引:1,自引:0,他引:1
钛硅分子筛TS-1由于其优异的催化氧化性能而受到极大关注,TS-1的制备及基础研究是催化领域的一个热点。本文重点综述了近年来钛硅分子筛催化材料的合成、改性及其催化应用的研究进展,包括钛硅分子筛(TS-1)的水热合成方法和同晶取代合成法、改性、成型与负载以及钛硅分子筛催化氧化功能和酸催化功能的研究。 相似文献
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Titanosilicates TS-1 with mesoporous/microporous hierarchical structures have been synthesized in the presence of an organosilane surfactant. Highly porous crystals, with regular pores of ca. 2.5–3.5 nm diameter, are obtained under hydrothermal conditions similar to those used for the preparation of conventional catalysts. The organosilane has a great influence on the textural properties of TS-1, but does not significantly affect the amount and coordination of Ti species in the framework. Mesoporous TS-1 have been used as catalysts in various oxidation reactions with an aqueous H2O2 and their activity has been compared with those of a conventional TS-1 and a mesoporous amorphous TiMCM-41. Data show that mesoporous TS-1 does not possess the expected properties for hierarchical catalysts, i.e. the properties of the conventional catalysts with advantages of mesoporous solids. In particular, the gain in diffusion due to intracrystalline mesopores is totally inhibited by the increase of the hydrophilic character of the zeolite, resulting from very high silanol group populations on the external surface. 相似文献
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Zirconium silicalite-1 (ZS-1) catalysts with MFI structure were prepared using a hydrothermal synthesis method. XRD, SEM,
IR,29Si MAS NMR, UV-VIS DRS, physical adsorption of nitrogen, and elemental analysis were then performed to evaluate its physico-chemical
properties, and evidences of Zr4+ incorporation into the zeolite framework were provided : The unit cell volume of zirconium silicalite-1 increased linearly
with increases in zirconium content, and the characteristic framework i.r. spectra shifted to lower frequencies as Zr4+ was incorporated into the silicalite-1 lattice. For its catalytic reaction test, liquid phase 2-butanol oxidation using hydrogen
peroxide as an oxidant was carried out. All of the zirconium silicalite-1 samples synthesized were active for the 2-butanol
oxidation, but activities obtained using ZS-1 catalysts were lower than TS-1 catalyst. Zirconium in the zeolite frameworkwas found to be the active site for the 2-butanol oxidation. 相似文献