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1.
利用XRD、XPS、TPR等技术对Ga2O3/HZSM-5催化剂进行表征,结果表明,催化剂中镓组分以聚集态和分散态的形式存在,其中聚集态中α-Ga2O3在一定条件下可转化为β-Ga2O3;分散态又可分为游离Ga2O3和与HZSM-5产生相互作用的镓组分,催化剂预处理条件及反应一再生过程对镓的分布及状态有较大影响。 相似文献
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用气相流动吸附法(grafting)制备复合载体,用浸渍法(impregnation)制备MoO3/(TiO2-SiO2)催化剂.应用LRS和TPR技术研究MoO3在复合载体TiO2-SiO2表面的分散状态,发现TiO2在SiO2表面的分散可增强MoO3与载体之间的相互作用,提高MoO3在载体表面的分散阈值.催化剂的活性评价在固定床中压反应装置中进行,以69%(wt)环己烷、20%(wt)的环己烯、10%(wt)的苯、1%(wt)的噻吩混合液为反应液,以噻吩、环己烯和苯的转化率作为催化剂的HDS、HYD、BHD活性指标.结果表明,经TiO2调变后,其HDS、HYD、BHD活性都较原来高,对于不同MoO3含量的MoO3/(TiO2-SiO2),HDS、HYD催化性能测试发现,当MoO3含量低于分散阈值时,其HDS、HYD活性随MoO3含量线性上升,但在高于分散阈值后,几乎保持不变.该催化剂对苯几乎没有加氢活性,显示出很高的环己烯加氢选择性.通过分散阈值与其HDS、HYD活性的关系可知,分散阈值可作为优化加氢精制催化剂配比的一个重要参数,具有较强的实际意义 相似文献
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Zn/HZSM-5分子筛上乙烯、乙烷芳构化的协同作用机理 总被引:2,自引:0,他引:2
运用NH_3-TPD、IR-OH、Py-IR、CO-IR及XPS等手段对Zn/HZSM-5及其浸碱催化剂的酸组分和金属组分构成的L酸性质进行了表征,考察了催化剂对乙烯、乙烷的芳构化作用.发现Zn/HZSM-5中形成了Zn ̄(2+)-L强酸中心,使分子筛的B酸中心减少.浸碱也可使分子筛的B酸减少,芳构化反应的活性和选择性均与Zn/HZSM-5的双中心Zn ̄(2+)-L酸和B酸的相互匹配密切相关,B酸和L酸存在最适合匹配,因此Zn/HZSM-5在乙烯、乙烷芳构化反应中存在最佳锌含量. 相似文献
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环己酮肟在改性氧化锆催化剂上的Beckmann重排反应Ⅲ.B_2O_3对ZrO_2的改性效应 总被引:1,自引:0,他引:1
采用IR和XRD技术研究了B2O3/ZrO2催化剂的结构性质,用ICP-MS测定了样品中B2O3的含量,通过Hammet指示剂正丁胺滴定法测定了B2O3/ZrO2系列催化剂的表面酸性;研究了载体预处理温度对样品表面酸性和结构的影响,以及B2O3含量对样品催化性能的影响;比较了B2O3负载于ZrO2,Al2O3,SiO2,TiO2,MgO和HZSM-5上催化活性和目的产物选择性的差异,讨论了B2O3/ZrO2催化剂在气固相Beckmann重排反应中的作用特点 相似文献
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Zn/HZSM—5分子筛上乙烯,乙烷芳构化的协同作用机理 总被引:2,自引:0,他引:2
运用NH3-TPD、IR-OH、Py-IR、CO-IR及XPS等手段对Zn/HZSM-5及其浸碱催化剂的酸组分和金属组分构成的L酸性质进行了表征,考察了催化剂对乙烯、乙烷的芳构化作用,发现Zn/HZSM-5中形成了Zn^2+-L强酸中心,使分子筛的B酸中心减少,浸碱也可使分子筛的B酸减少,芳构化反庆的活性和选择性均与Zn/HZSM-5的双中心Zn^2+-L酸的相互匹配密切相关。B酸和L酸存在最适合 相似文献
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高活性沸石酯化催化剂的研究 总被引:2,自引:0,他引:2
用硼酸和硫酸对含Al2O3的β和ZSM5沸石进行处理,制备了一系列沸石MxOy和SO24/沸石MxOy)催化剂。用NH3TPD和Hammett指示剂法测定了催化剂的表面酸性。对H2SO4处理的样品进行了X射线物相分析。用BET法测定了Hβ及HZSM538对乙酸的吸附等温线和饱和吸附量。对催化剂的活性,均通过乙酸和乙醇在液相、90℃和不分水条件下的酯化进行表征。结果表明,HβAl2O3经硼酸和硫酸处理后,乙酸的转化率由39.53%提高到54.92%。HZSM538Al2O3经同样处理后,乙酸的转化率由24.45%提高到44.87%。SO24/沸石MxOy的最佳焙烧温度范围是500~550℃。此外,在固定床反应器内于100~130℃和LHSV为6h1的条件下,对SO24/HβAl2O3B2O3的活性位的稳定性进行了初步实验。反应在110℃连续进行12h后,乙酸的转化率始终稳定在69%左右。 相似文献
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沸石在环己烯水合反应中的催化性能 总被引:1,自引:0,他引:1
用Hβ及不同方法制得的HZSM-5沸石作催化剂,对环己烯-水,环己烯-水-乙酸两种反应体系中的水合反应进行了研究。用GC-IR对产物进行了定性分析。用BET重量法测定了各种沸石对反应物的饱和吸附量。结果表明,在两种反应体系中,Hβ的催化活性显著地高于HZSM-5。GC-IR分析表明,在HZSM-5上,主要副产物是环己烯-[1]-酮-[3]和4-甲基环戊烯;在Hβ沸石上,主要副产物是2-环己烯基环己 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
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Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described. 相似文献
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用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在. 相似文献
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Jona Mirnik Eva Pušavec Kirar Sebastijan Ričko Uroš Grošelj Amalija Golobič Franc Požgan Bogdan Štefane Jurij Svete 《Tetrahedron》2017,73(24):3329-3337
A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu0 as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than CuI in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT). 相似文献
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George E. Magoulas Thomas Garnelis Constantinos M. Athanassopoulos Dionissios Papaioannou George Mattheolabakis Konstantinos Avgoustakis Dimitra Hadjipavlou-Litina 《Tetrahedron》2012,68(35):7041-7049
(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C60, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine. 相似文献