共查询到18条相似文献,搜索用时 187 毫秒
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在离子液沐中,采用钨酸为催化剂,用过氧化氢水溶液为氧化剂,一步催化氧化环戊烯合成戊二醛。催化体系经4次循环,催化活性未见明显降低,并进一步讨论了CPE与H2O2物料配比、反应温度、反应时间对戊二醛收率的影响,并确定了最佳合成工艺条件:n(C5H8):n(H2O2)=1:4,反应温度40℃,反应时间8hr。戊二醛总收率73%。 相似文献
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以钨酸为原料,通过原位合成法将W~(6+)引入六方介孔全硅分子筛HMS骨架中,制备了W- HMS催化剂。采用XRD、FT-IR以及EDS对所得催化剂结构进行了表征,并通过环戊烯过氧化氢非均相催化氧化制备戊二醛,考察了其催化活性。结果显示,W-HMS催化剂的催化性能与W的量密切相关.在n_(si)/n_w(物质的量比)大于或等于30时,催化剂保持了完好的HMS分子筛结构,W原子以嵌入HMS骨架的形式高度分散于载体内表面,构成催化活性中心,对环戊烯氧化反应转化率可达100%,生成戊二醛的选择性达79.3%。 相似文献
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环戊烯催化氧化合成戊二醛的研究 总被引:1,自引:0,他引:1
对环戊烯催化氧化合成戊二醛的工艺进行了研究,考查了影响反应的主要因素,摸索出最佳工艺路线:在叔丁醇溶剂中,以钨酸与硼酐(质量比为1:1)为催化剂,双氧水为氧化剂,反应时间为4h,温度为35℃,戊二醛的收率约为46%。 相似文献
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对羟基苯甲酸丁酯的合成及催化剂的选择 总被引:2,自引:0,他引:2
对以正丁醇和对羟基苯甲酸为原料合成对羟基苯甲酸丁酯的催化剂及反应条件进行了研究。硫酸氢钠是合成对羟基苯甲酸丁酯的一个新型、良好的催化剂。最佳反应条件为:醇酸摩尔比为4:1,催化剂用量为对羟基苯甲酸质量的5%,反应时间为4h。上述条件下对羟基苯甲酸丁酯的收率为91%。 相似文献
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Tungsten-containing hexagonal mesoporous silica (W-HMS) supported tungsten oxide catalysts (WOx/W-HMS) was prepared for the selective oxidation of cyclopentene with aqueous hydrogen peroxide to glutaraldehyde. X-ray diffraction (XRD) results indicated that the crystal form of the active phase (tungsten oxide) of the WOx/W-HMS catalysts was dependent on the W loading and calcination temperature. X-ray photoelectron spec- troscopy (XPS) analysis revealed that the dispersed tungsten oxides on the surface of W-HMS support consisted of a mixture of W(V) and W(VI). It was found that a high content of amorphous W species in (5+) oxidation state resuited in the high catalytic activity. When the W loading was up to 12% (by mass) or the catalyst precursor was treated at temperature of 623 K, the catalytic activity decreased due to the presence of WO3 crystallites and the oxidation of W(V) to W(VI) on the catalyst surface. Furthermore, NH3-temperature-programmed-desorption (NH3-TPD) analysis showed that the effects of W loading and calcination temperature on the acidity of the catalysts were related to the catalytic activity. A high selectivity of 80.2% for glutaraldehyde with a complete conversion of cyclopentene was obtained over 8%WOx/W-HMS catalyst calcined at 573 K after 14 h of reaction. 相似文献
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W-modified HMS and SBA-15 mesoporous materials (Si/W molar ratio equal to 40) were synthesized using sodium tungstate as tungsten
source. In order to prepare NiW catalysts these mesoporous materials were impregnated with an aqueous solution of nickel salt
of 12-tungstophosphoric acid Ni3/2PW12O40. The synthesized W-HMS, W-SBA-15 materials and NiW catalysts have been characterized by SBET, XRD, UV–Vis DRS, FT-IR, TPD of NH3, 29Si MAS NMR, SEM and HRTEM. The influence of these particular supports on catalytic activity of NiW catalysts was studied in
the reaction of hydrodesulfurization (HDS) of thiophene. The results from the FT-IR and UV–Vis DR spectroscopy confirm incorporation
of W into the HMS and SBA-15 structures. Additionally 29Si MAS NMR measurements revealed relatively stronger effect of W ion incorporation in HMS structure on degree of silica cross-linking
as compared to the effect of W ion incorporation in SBA-15 structure. The catalytic study showed that both W-HMS and W-SBA-15
materials modified with W are good supports for NiW catalysts in the HDS reaction of thiophene. The catalysts show lower selectivity
for butanes than a reference NiW/γ-Al2O3 catalyst leveling of about 10% for chosen experimental conditions. 相似文献
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Qian Zhao Jinyu Chu Tingshun Jiang Hengbo Yin 《Korean Journal of Chemical Engineering》2008,25(5):1008-1013
Mesoporous titania was prepared by hydrothermal method and mesoporous titania solid superacid catalyst was prepared by wet
impregnation method. The structure and property of the as-prepared catalysts were characterized by means of XRD, FT-IR and
N2 physical adsorption. Isoamyl salicylate was synthesized by using concentrated sulfuric acid and solid superacid as catalyst,
respectively. The effects of the molar ratio of raw material, the amount of catalyst, reaction time and reaction temperature
on the yield of the product were systematically investigated. The results show that mesoporous titania solid superacid is
a good catalyst for synthesizing isoamyl salicylate. The optimum conditions of isoamyl salicylate synthesized by using mesoporous
titania solid superacid are the following: the molar ratio of salicylic acid to isoamyl alcohol is 1: 4, the quantity of catalyst
is 1.6 g, the reaction time is 5 h, the reaction temperature is 130 °C and the yield can reach 94.6%. 相似文献
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采用浸渍法制备了Sb-SBA-15催化剂,通过XRD、N2吸附-脱附、FTIR对其进行表征,结果表明,Sb-SBA-15催化剂仍具有六方介孔结构。考察了苯/氯化苄的摩尔比、反应时间、催化剂用量、反应温度对Sb-SBA-15催化苯与氯化苄苄基化反应的影响,并研究了反应的动力学。实验结果表明,Sb-SBA-15对苯与氯化苄的苄基化反应具有良好的催化性能,最佳反应条件为:苯与氯化苄的摩尔比8、反应时间3h、催化剂用量0.1g、反应温度120℃。在最佳条件下,氯化苄的转化率可达96.78%,二苯甲烷的选择性高达99%以上。 相似文献
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用巯丙基硅氧烷对磁性介孔硅胶改性,并通过烯丙基官能化离子液体的双键与巯基之间的自由基加成反应将具有不同侧链烷基的离子液体负载到磁性介孔硅胶表面,制备了磁性介孔硅胶负载碱性离子液体催化剂.采用红外光谱分析、X射线衍射、有机元素分析、氮气物理吸附/脱附分析和样品振动磁强计对催化剂的结构和磁性能进行了表征,最后通过催化三油酸甘油酯与甲醇酯交换反应对其催化性能进行了评价.结果表明,随着离子液体侧链烷基碳个数的增多,磁性介孔硅胶负载离子液体催化剂的离子液体负载量降低,比表面积和孔体积降低.当离子液体侧链烷基为辛基、十二烷基或十六烷基时,油酸甲酯产率均高于95%,并且反应3次后油酸甲酯产率依然高于90%. 相似文献
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介孔SO_4~(2-)/ZrO_2的制备、表征及性能 总被引:1,自引:0,他引:1
以正丙醇锆为锆前躯体,硫酸铵为硫源,十六烷基三甲基溴化铵(CTAB)为模板剂,溴化钾为添加剂,按n(Zr4+)∶n(CTAB)∶n(SO24-)=2∶1∶2,在水热条件、酸性介质中合成了介孔ZrO2/SO24-。通过X射线衍射(XRD),N2物理吸附,扫描电镜(SEM),FTIR分析手段对其结构进行了表征;并以乙酸正丁酯的酯化反应为探针反应,考察了其催化活性。结果表明,采用两步焙烧法去除模板剂后,该样品的介孔结构类似于MCM-41,d值为3.85nm;在500℃焙烧后,该样品仍具有274m2/g的比表面积及3.2nm的平均孔径;SEM显示焙烧后的样品形貌为球形颗粒;FTIR分析得出,焙烧产物ZrO2/SO42-中S=O键对Zr4+有强的吸电子作用,产生强的Lewis酸中心。当催化剂用量为正丁醇质量的2.5%,n(乙酸)∶n(正丁醇)=1∶2,反应3h后,乙酸的转化率达91.48%。 相似文献
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以SO42-/ZrO2为母体,引入稀土元素La、Ce对其进行改性,制备出一系列稀土固体超强酸催化剂,用X射线衍射、红外光谱和BET手段表征了催化剂的物化性能。研究了催化剂合成生物柴油的催化性能,系统考察了n(甲醇):n(脂肪酸甘油三酯)、催化剂用量、反应温度、反应时间等因素对生物柴油产率的影响。结果表明:稀土的引入使活性四方相ZrO2更加稳定;催化剂中形成了固体超强酸结构,且改性后酸强度增大,催化剂活性中心数目增加。SO42-/ZrO2-La2O3的催化活性较高,n(甲醇)∶n(脂肪酸甘油三酯)=10∶1、m(催化剂)∶m(原料油)=4∶100、反应温度250℃、反应时间9 h,此时甲酯的产率可达到73.46%。该催化剂活性较高,重复使用3次后生物柴油产率仍在60%之上。 相似文献