Journal ArticleDOI
Catalytic activity of highly ordered mesoporous VMCM-48
Parasuraman Selvam,S.E. Dapurkar +1 more
Reads0
Chats0
TLDR
In this article, mesoporous VMCM-48 molecular sieves with Si/V (molar) ratios of 25-200 were synthesized hydrothermally and systematically characterized by various analytical and spectroscopic techniques, viz, XRD, N 2 sorption, TG-DTA, TEM, EPR, 51 V MAS-NMR, FT-IR, and DRUV-VIS XRD studies suggest that the substitution of vanadium occurs in the silicate framework structure of MCM- 48.Abstract:
Mesoporous VMCM-48 molecular sieves with Si/V (molar) ratios of 25–200 were synthesized hydrothermally and systematically characterized by various analytical and spectroscopic techniques, viz, XRD, N 2 sorption, TG-DTA, TEM, EPR, 51 V MAS-NMR, FT-IR, and DRUV-VIS XRD studies suggest that the substitution of vanadium occurs in the silicate framework structure of MCM-48 TEM and ED investigations confirm the highly ordered cubic structure of VMCM-48 EPR and 51 V NMR studies indicate the presence of pentavalent vanadium ions in tetrahedral framework positions, while DRUV-VIS spectra show their existence in two different environments The catalytic activity of these well-characterized (both in the calcined and the washed forms) materials was evaluated for cyclohexane oxidation under mild reaction conditions All these catalysts gave high substrate conversion and excellent product (cyclohexanol) selectivity Furthermore, unlike many other vanadium-based heterogeneous catalysts reported, the mesoporous VMCM-48 catalysts show minimal leaching of the active vanadium species This was confirmed by washing, recycling and quenching experiments where only a small amount of vanadium ions leaches out in the case of calcined samples, while vanadium was not detected for the washed ones Finally, the catalytic activity of VMCM-48 was also compared with mesoporous VMCM-41 as well as microporous VS-1 catalyst The results indicate that the former showed superior activity to those of the latter two, such superiority could, however, be directly related to the amount of vanadium incorporated in MCM-48 being larger than the amounts in MCM-41 and MFI structuresread more
Citations
More filters
Journal ArticleDOI
Catalytic oxidation of cyclohexane to cyclohexanone and cyclohexanol by oxygen in a solvent-free system over metal-containing ZSM-5 catalysts
TL;DR: In this paper, the authors used Co/ZSM-5 catalysts for the cyclohexane oxidation and showed that the Co-ZSM5 catalyst achieved about 10 millmol% conversion of liquid cyclomethane and 97% selectivity of KA-oil under the pressure of 1.0 MPa O 2.
Journal ArticleDOI
Vanadium-containing ordered mesoporous silicates: Does the silica source really affect the catalytic activity, structural stability, and nature of vanadium sites in V-MCM-41?
TL;DR: In this paper, a series of vanadium-substituted mesoporous materials were synthesized hydrothermally with the use of two commonly used silica sources, fumed silica and tetra ethyl orthosilicate.
Journal ArticleDOI
Synthesis of lanthanum-doped MCM-48 molecular sieves and its catalytic performance for the oxidation of styrene.
Wangcheng Zhan,Yanglong Guo,Yanqin Wang,Xiaohui Liu,Yun Guo,Yunsong Wang,Zhigang Zhang,Guanzhong Lu +7 more
TL;DR: Lanthanum-doped MCM-48 molecular sieves with different La contents were synthesized hydrothermally and characterized by X-ray diffraction (XRD), nitrogen sorption, transmission electron microscopy (TEM), UV-visible spectroscopy, and Fourier transform infrared (FT-IR) spectroscopic.
Journal ArticleDOI
Synthesis, characterization and catalytic application of mesoporous W-MCM-48 for the selective oxidation of cyclopentene to glutaraldehyde
TL;DR: Tungsten-containing ordered MCM-48 has been synthesized under hydrothermal conditions via pH adjustment and characterized with various analytical and spectroscopic techniques, including X-ray diffraction (XRD), N 2 adsorption, transmission electron micrographs (TEM), scanning electron micro graph (SEM), Laser-Raman spectroscopy, UV-vis diffuse reflectance spectrograph (UV-vis DRS), Fourier-transform infrared spectrogram (FT-IR) and ammonia temperature-programmed desorption (NH 3 -T
Journal ArticleDOI
High desulfurization characteristic of lanthanum loaded mesoporous MCM-41 sorbents for diesel fuel
TL;DR: In this article, the results of N 2 -adsoption isotherms, XRD, HRTEM and FT-IR for the sorbents revealed that no structure collapse occurred during the wet impregnation, and the interaction between sulfur in thiophene and HO-La(OSiAl) was crucial for the removal of sulfur compounds.
References
More filters
Journal ArticleDOI
Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984)
TL;DR: Mise au point comportant des definitions generales et la terminologie, la methodologie utilisee, les procedes experimentaux, les interpretations des donnees d'adsorption, les determinations de l'aire superficielle, and les donnes sur la mesoporosite et la microporosite.
Journal ArticleDOI
A new family of mesoporous molecular sieves prepared with liquid crystal templates
Jeffrey S. Beck,James C. Vartuli,Wieslaw J. Roth,M. E. Leonowicz,Charles T. Kresge,Kirk D. Schmitt,Cynthia Ting-Wah Chu,David H. Olson,E. W. Sheppard,S. B. McCullen,J. B. Higgins,J.L. Schlenker +11 more
TL;DR: In this paper, the synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described.
Journal ArticleDOI
Studies on mesoporous materials: I. Synthesis and characterization of MCM-41
TL;DR: The mesoporous molecular sieves MCM-41 were synthesized and characterized by X-ray powder diffraction, nitrogen adsorption/desorption, cyclohexane and water adaption, transmission electron micrographs (TEM), thermogravimetric analysis (TGA), ammonia temperature-programmed desorption (TPD), FTIR, FT-Raman, 29Si, 27Al and 13C magic angle spinning (MAS) NMR spectroscopy.
Journal ArticleDOI
Cyclohexane oxidation continues to be a challenge
Ulf Schuchardt,Dilson Cardoso,Ricardo Sercheli,Ricardo Pereira,Rosenira Serpa da Cruz,Mário César Guerreiro,Dalmo Mandelli,Estevam V. Spinacé,Emerson L. Pires +8 more
TL;DR: In this article, the most interesting systems for the cyclohexane synthesis with different oxidants such as hydrogen peroxide, tert -butyl hydroperoxide and molecular oxygen were reviewed.