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1.
镧改性铁催化剂的研究Ⅱ.镧改性铁催化剂的碳化性能   总被引:1,自引:0,他引:1  
周钰明  丁莹如 《催化学报》1993,14(5):383-386
用穆斯堡尔谱和Cahn微量天平技术研究了Fe2O3/γ-Al2O3,Fe2O3-La2O3/γ-Al2O3和Fe2O3/La2O3/γ-Al2O3催化剂的碳化性能。结果表明:铁碳化物的生成与催化剂活性组分同载体的相互作用有关。La2O3改性后的Fe2O3/La2O3/γ-Al2O3催化剂,由于活性组分与载体之间存在强相互作用,在F-T反应过程中没有检测到铁碳化物相。同时,La2O3的添加提高了催化  相似文献   

2.
沈俭一  林励吾 《催化学报》1993,14(5):343-348
用原位穆斯堡尔谱考察了不同担载量的Fe/AC催化剂的氮化以及随后的碳化行为。Fe/AC催化剂经500℃H预还原后,于350℃流动态氨气中氮化5小时可生成ε-氮化铁,其穆斯堡尔谱呈双峰(δ~0.42mm/s,△~0.32mm/s)。再在合成气(2H2/CO)中进行碳化处理,ε-氮化铁中的氮原子可逐渐被碳原子取代而转化为氮碳化铁和碳化铁,但铁的担载量越高,这种取代越困难。8%Fe/AC催化剂在250℃  相似文献   

3.
用浸渍法制得一系列不同铁负载量的Fe2O3/ZrO2催化剂,应用催化反应评价结合穆斯堡尔谱对催化剂的CO加氢反应性能、催化剂活性相结构及催化剂铁物种在合成气反应过程中的物相变化进行了研究.结果表明,铁负载量的大小对于Fe2O3/ZrO2催化剂的F-T反应催化性能有很大影响,铁负载量适当时,Fe2O3/ZrO2催化剂铁锆间适当的强相互作用使得催化剂在保持较高催化活性的同时高选择性地生成低碳烯烃,产物分布偏离Schulz-Flory分布规律.  相似文献   

4.
陈开东  范以宁 《分子催化》1995,9(6):451-456
应用X-射线衍射,程序升温还遥,穆斯堡尔谱以及CO+H2催化反应性能测试等手术研究了K,Mn,La,Ce四种助剂对Fe2O3/ZrO2催化剂结构,还原行为以及CL+H2反应催化性能的影响。  相似文献   

5.
四核过渡金属簇合物[Fe_4O_2(OAc)_7(bipy)_2]Cl和[Fe_2Cr_2O_2(OAc)_7(bipy)_2]Cl的穆斯堡尔研究王友桐(中国科学院福建物质结构研究所,福州350002)余秀芬,潘文瑜(福州大学化学系,350002)四...  相似文献   

6.
应用连续催化反应,XPS,XRD,H2-TPR,O2-TPD和In-situ Mossbauer谱等方法表征了一系列组成不同的NaCl/B2O3/Fe2O3催化剂。结果表明NaCl与B2O3在修饰FeOx催化剂上存在明显的协同作用,B2O3调变了FeOx的还原能力,NaCl修饰了B2O3/FeOx使之具有很高的还原速度与晶格氧气化速度。催化剂的催化性能同这种协同作用密切相关。  相似文献   

7.
使用原位穆斯堡尔谱考察了γ-Al2O3、SiO2、TiO2和ZrO2等几种载体担载的氧化铕催化剂的还原性。非担载Eu2O3很难在H2中原,而Eu2O3与γ-Al2O3、SiO和TiO2间存在着强相互作用,担载在这些载体上的Eu2O3在773K左右H2中处理可有不同程度的还原,其还原度反映了相互作用的强弱,为:Eu/γ-Al2O3>Eu/TiO2>Eu/SiO2>Eu/ZrO2、Eu/ZrO2不能在  相似文献   

8.
用穆斯堡尔谱及XRD技术对不同铁氧化物前驱态的相变过程进行了,FeCO3沉淀在空气中老化时被氧化分解生成FeO(OH),经干燥、煅烧后合部转化为a-Fe2O3。(Fe(OH)2沉淀物在空气中老化时则转化为Fe3O4.2H2O和FeOOH,两者的相对含量受Fe^2+的迁移速率和Fe(OH)2的氧化速度的影响。  相似文献   

9.
采用穆斯堡尔谱及X光衍射法研究了共沉淀法制备的不同Fe/Mn比催化剂在焙烧、合成气还原及FT反应后体系相结构的变化。结果表明:锰助剂的加入使催化本相由铁磁性逐渐转化为超顺磁性,相应使催化剂还原逐渐难,Mn助剂促进了FT合成反应进行。反应性能与Fe/Mn尖晶石(Fe1-yMny)3O4组成含量及式中y大小密切相关,与MnCo3及MnO的存在也有一定关系。富铁催化剂中Mn主要起电子助剂作用,而富锰催化  相似文献   

10.
纳米尺寸铁酸锌半导体催化剂的表征及催化性能研究   总被引:12,自引:0,他引:12  
采用改进的化学共沉淀法制备了不同平均粒径的ZnFe2O4纳米晶体,利用X-射线衍射和透射电镜技术对其超微结构和表面形貌进行了研究.着重利用付里叶变换红外光谱和穆斯堡尔谱对其谱学特性(“量子尺寸效应”和“穆斯堡尔效应”)进行了研究,并详细探讨了纳米ZnFe2O4催化剂对光催化性能的影响,得出了一些有意义的结论  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.
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   

14.
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   

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.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

19.
20.
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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