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  • Palladium catalyzed N-alkylation of amines with alcohols
  • 更新时间:2014-04-10;信息类型:SCI论文
  • An iron oxide immobilized palladium catalyst was prepared for the N-alkylation of amines with alcohols under base and organic ligand free conditions. Applying the optimized reaction conditions, the coupling reactions of amines and alcohols with various structures could be realized with up to 99% isolated yields. The catalysts were studied by XRD, BET, and XPS and the mechanism was studied by DFT calculations.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/138.html
  • Organic Ligand-Free Alkylation of Amines, Carboxamides, Sulfonamides,and Ketones by Using Alcohols Catalyzed by Heterogeneous Ag/Mo Oxides
  • 更新时间:2014-04-10;信息类型:SCI论文
  • Complicated and expensive organic ligands are normally essential in fine chemical synthesis at preparative or industrial levels. The synthesis of fine chemicals by using heterogeneous catalyst systems without additive organic ligand is highly desirable but severely limited due to their poor generality and rigorous reaction conditions. Here, we show the results of carbon–nitrogen or carbon–carbonbond formation catalyzed by an Ag/Mo hybrid material with specific Ag6Mo10O33 crystal structure. 48 nitrogen-or oxygen-containing compounds, that is, amines, carboxamides, sulfonamides, and ketones, were successfully synthesized through a borrowing-hydrogen mechanism. Up to 99% isolated yields were obtained under relatively mild conditions without additive organic ligand. The catalytic process shows promise for the efficient and economic synthesis of amine, carboxamide, sulfonamide, and ketone derivatives because of the simplicity of the system and ease of operation.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/137.html
  • N-substituted carbamates syntheses with alkyl carbamates as carbonyl source over Ni-promoted Fe3O4 catalyst
  • 更新时间:2014-04-10;信息类型:SCI论文
  • A series of catalysts of magnetic iron oxide containing Ni with different nickel content were prepared with co-precipitation method and tested in the syntheses of N-substituted carbamates from various amines and alkyl carbamates. Under the optimized reaction conditions, various N-substituted carbamates were successfully synthesized with 90–98% isolated yield. The catalyst could be recovered based on the magnetic property of the catalyst and reused for five runs without deactivation. The catalysts were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption, and Mössbauer spectroscopy analyses. The results showed that the catalytic activity may be derived from the delicate synergy between Ni and Fe species resulted in specific basic sites. Quasi in situ FT-IR and isotopic tracer revealed that the formation of substituted urea was the key step and the N-substituted carbamate was formed via further alcoholysis of the substituted urea.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/131.html
  • Atom-economy Synthesis of N-substituted Carbamate from Urea Derivative and Dimethyl Carbonate Catalyzed by La/SiO2: Characterization and Activity
  • 更新时间:2014-04-10;信息类型:SCI论文
  • A series of silica gel immobilized lanthanum catalysts were prepared for the atom-economy synthesis of N-substituted carbamates from urea derivatives and dimethyl carbonate. The La/SiO2 catalysts with lanthanum loadings varied from 1.3 wt% to 8.5 wt% were characterized by AES, BET, XRD, TEM, FT-IR, XPS and TPD. According to the characterization, lanthanum species with particle sizes of 5—10 nm on the surface of silica gel were formed. The catalysts were all amorphous and the surface areas were 336.5—530.2 m2/g. NH3-TPD analysis showed that all samples exhibited similar acid strength with different acid amounts. FT-IR measurement indicated that the component of lanthanum speci es on the catalyst surface were La(OH)3, LaOOH and hydrated La2O3. Also, the peak value of the absolute amount of LaOOH was obt ained with 4.3 wt% lanthanum loading. The BET surface area decreased dramatically when the lanthanum loading was above 4.3 wt%. In consideration of the results ob-tained from the catalytic reactions, it could be concluded that LaOOH was the possible active species and high sur-face area was important for the high catalytic activity.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/130.html
  • Low-temperature CO oxidation over supported Pt, Pd catalysts: Particular role of FeOx support for oxygen supply during reactions
  • 更新时间:2014-04-10;信息类型:SCI论文
  • A series of FeOx- and Al2O3-supported Pt, Pd catalysts (0.23–2.1%) were prepared in this study. Pt/FeOx exhibited high CO oxidation activity with turnover frequency of 151 10 3 s 1 (1% CO balanced with air, atmospheric pressure, 27 C). A systematical study of FeOx- and Al2O3-supported Pt, Pd catalysts by means of X-ray photoelectron spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed reduction, H2–O2 titration, and time-resolved CO titration is reported. From 7% to 39% of Fe3+ was reduced to Fe2+ over Fe(OH)x-supported Pd and Pt catalysts, accompanied by Pd, Pt hydrogenation and hydroxyl loss, and a large amount of oxygen vacancies were proposed to be produced. Results of H2–O2 titration and time-resolved CO titration showed that a large amount of oxygen adsorbed onto FeOx support in the presence of Pt, Pd. This made CO oxidations over Pt/FeOx, Pd/FeOx proceed over two adjacent but different active sites (Pt, Pd for CO and FeOx for oxygen) with low apparent activation energies (30–34 kJ/mol), which accounted for their high activity in low-temperature CO oxidation.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/124.html
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