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1.
在凝胶体系NaX(F、Cl、Br)Na2OAl2O3SiO2CTAB(十六烷基三甲基溴化铵)H2O中,研究了水热合成中孔MCM41的合成条件。实验证明,在398K下晶化8~16d,NaX/SiO2介于0.01~0.05时,均可合成出MCM41分子筛;NaF的加入,可以加快MCM41分子筛的晶化速度;NaBr的加入,对形成MCM41分子筛有阻碍作用。采用XRD、SEM、TGDTA和N2吸附对合成样品加以表征,证明合成样品具有介孔分子筛特性。  相似文献   

2.
钒硅MCM—41沸石分子筛微波合成与表征   总被引:5,自引:0,他引:5  
以溴代十六烷基吡啶(CPBr)为模板剂,硅溶胶为硅源,用微波辐射的方法成功地合成出了高结晶度的中孔杂原子VMCM-41分子筛,探讨了微波反应釜压力、微波晶化时间、老化时间等合成因素的影响,确定了合适的配比范围及合成条件。利用XRD、TEM、IR等方法对VMCM-41中孔分子筛的结构作了表征,结果表明钒已进入分子筛骨架  相似文献   

3.
Eu(TTA)3/MCM—41介孔复合体的溶胶—凝胶法组装   总被引:2,自引:0,他引:2  
利用溶胶-凝胶法将稀土的Eu(TTA)3组装到MCM-41介孔分子筛的孔道中,并初步认定客体分子Eu(TTA)3是以加合物形式包裹于表面活性剂胶束中。该法制得的介孔复合体Eu(TTA)3/MCM-41,用XRD、HRTEM技术证实有短程有序的,规整的六方介孔结构和大小分布均匀的纳米晶粒。对其光致发光和荧光寿命的研究发现,与乙醇溶液中相比,Eu^3+的荧光寿命没有发生改变,但Stokes位移却明显增大;复合体中,能量是从主体MCM-41传递到客体Eu(TTA)3上。  相似文献   

4.
MCM-41中孔分子筛的合成及其性质   总被引:2,自引:2,他引:0  
以十六烷基三甲基溴化铵(CTAB)作模板剂,研究了水热体系中中孔MCM-41分子筛的合成条件。在H_2O/Si介于12~100,Si/Al介于10~∞,CTAB/Si介于0.08~0.2时,可以合成出MCM-41分子筛。在加入煤油等混合烃的合成体系中,可以合成出孔径大于4nm的MCM-41分子筛。用XRD、SEM、N_2吸附对合成样品加以表征,证明它们具有典型的中孔分子筛特性。探针反应证明它具有中强酸中心。  相似文献   

5.
MCM—48介孔分子筛的合成研究   总被引:14,自引:3,他引:11  
利用水热法合成了MCM-48介孔分子筛,通过IR,TG-DTA,XRD,XRD,TEM,N2吸附等方法对产物进行了表征,并系统地研究了晶化温度、晶化时间、凝胶组成等对合成MCM-48介孔分子筛的影响。  相似文献   

6.
MCM—41介孔分子筛合成研究:Ⅱ.微波辐射合成法   总被引:1,自引:1,他引:0  
许磊  刘宪春 《催化学报》1999,20(3):251-255
采用微波辐射技术合成了MCM-41介孔分子筛,并用XRD,SEM,IR,NMR和吸附等表征手段考察了其晶化过程,晶体形貌和稳定性等特点,结果表明,微波法合成MCM-41分子筛时诱导期极短,晶化速度很快且在晶化后期无转晶现象;微波法合成的MCM-41试样的吸附容量较低,但具有较强的耐热及水热稳定性和抗酸碱能力。  相似文献   

7.
MCM—41介孔分子筛合成研究:Ⅰ.水热合成法   总被引:1,自引:0,他引:1  
许磊  王公慰 《催化学报》1999,20(3):247-250
以十六烷基三甲基溴化铵为附加试剂合成了MCM-41介孔分子筛,并用XRD,SEM和IR等表征手段考察了晶化时间、晶化温度、物料组成和附加试剂用量等对其晶化过程的影响。结果表明,MCM-41介孔分子筛的晶化诱导期较长,在晶化后期存在着转晶现象,而且有一较适宜的晶化温度,物料组成和附加试剂用量范围。  相似文献   

8.
合成温度对中孔分子筛M41S材料结构转变的影响   总被引:7,自引:4,他引:3  
分别用氮气吸附-脱附测定、激光傅立叶红外(FTIR)、^29Si和^27Al固态魔角核磁共振(MASNMR)和微分热重(DTG)等手段表征了低表面活性剂浓度及低表面活性剂与硅原子摩尔经的十六烷基三甲基溴化铵与硅酸钠体系中不同温度形成的不同中孔M41S和微孔ZSM-5沸石,研究发现,合成温度从100℃温度至135℃,MCM-41的固体颗粒变细,孔壁厚增加而中孔表面积和体积降低,合成温度从135℃提高  相似文献   

9.
Cu修饰的MCM—41的合成,表征及对芳烃羟化反应催化作?…   总被引:15,自引:1,他引:14  
利用MCM-41形成过程中协同自组装特点,在合成过程中引入Cu(NH3)4^2+,制备出过渡金属表面修饰的纯硅介孔分子筛Cu-MCM-41,采用XRD,ICP,ESR,N2吸附等手段确定Cu处于MCM-41的表面,取代了端羟基中氢的位置,与骨架桥氧和硅羟基中的氧配位,利用苯酚羟化反应为探针,考察了Cu-MCM-41的催化活性。结果表明,Cu-MCM-41具有很高的苯酚羟化活性,与TS-1分子筛的催  相似文献   

10.
本文采用表面活性剂十六烷基三甲基溴化铵(C16TABr,以下为1631),在(Na,K)OHSiO2C16TABrH2O体系中分别利用室温、水热及干粉法进行了纯硅MCM41中孔分子筛的合成,考察了阳离子Na+、K+对MCM41合成及稳定性的影响。通过XRD对结晶度的测定,发现NaMCM41的晶化速率明显高于KMCM41,而热稳定性和水热稳定性较差,且a0值小于后者。同时发现,就合成方法而言,室温法得到的产物具有很高的结晶度,利用水热法合成的样品的热稳定性明显较高,而干法得到的分子筛产品具有优良的水热稳定性。  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
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   

16.
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   

17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
19.
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   

20.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

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