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1.
高志贤  程昌瑞 《分子催化》1997,11(4):268-272
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   

2.
氟氯有机化合物对HZSM-5分子筛改性过程中氟和氯的作用   总被引:2,自引:0,他引:2  
利用XRD,MAS,NMR,IR和XPS等手段研究了CF4-nCln改性的HZSM-5分子筛的体相和表面结构的变化。结果表明,改性过程中F和Cl均能使HZSM-5脱铝和脱硅。Cl可以使沸石骨架SiO2/Al2O3升高,而F除使沸石骨架脱铝外,还会极化其晶格。F比Cl更容易在沸石表面富集。F和Cl是通过取代O或OH与沸石表面Si或Al作用的。改性后的沸石表面有数种含氟表面物种存在。  相似文献   

3.
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   

4.
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   

5.
首次介绍了一种以HZSM-5为载体,以La2O3为促进剂,采用浸渍法制成的Fe2O3-La2O3/HZSM-5新型催化剂,在常压,反应温度为300℃条件下,以H2O2为氧化剂使苯羟基化为苯酚,取得了苯的最高转化率和苯酚的选择性分别达到40.2%和94.0%的结果。  相似文献   

6.
根据实验结果,从理论上分析了Al2O3无机膜反应器对HZSM-5,0.4%Ga/HZSM-5和0.5%Pt-0.4%Ga/HZSM-5催化剂上丙烷芳构化反应历程的影响。结果表明,氢气在烷烃活化、环烃形成芳烃和低碳烯烃加氢过程中担当着重要角色,膜反应器通过影响这些步骤,进而影响整个芳构化反应的选择性。  相似文献   

7.
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   

8.
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   

9.
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   

10.
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   

11.
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   

12.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
19.
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   

20.
(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   

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