Go toArchive
Browse byFacets
Bookbag ( 0 )
'Zeolites' in keywords
Results  7 Items
Sorted by   
Publication Year
2001 (1)
1999 (1)
1998 (1)
1996 (2)
1995 (1)
1981 (1)
1Author    Fritz Seel, Willi Schaum, Georg SimonRequires cookie*
 Title    Über die Entstehung von Zuckern und zuckerähnlichen Substanzen aus in Zeolithen absorbiertem Formaldehyd durch UV-Bestrahlung Synthesis of Sugars and Sugar-Like Products by UV Irradiation of Formaldehyde Absorbed on Zeolites  
 Abstract    The formation of sugars and sugar-like substances by UV irradiation of formaldehyde adsorbed on zeolites of type A and X has been demonstrated. The conversion inside or outside the matrix and product distribution depend on the type of zeolite. 
  Reference    Z. Naturforsch. 36b, 1451—1456 (1981); eingegangen am 7. Mai 1981 
  Published    1981 
  Keywords    Formaldehyde, Sugars, Zeolites 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1451.pdf 
 Identifier    ZNB-1981-36b-1451 
 Volume    36 
2Author    A. Seidel, B. BoddenbergRequires cookie*
 Title     
 Abstract    S tu d y o f th e D is tr ib u tio n o f S o d iu m C a tio n s in th e Z e o lite s N a X , N a Y a n d Z n N a Y U s in g C a r b o n M o n o x id e A d s o rp tio n a n d 23N a N M R T e c h n iq u e s Herrn Professor Dr. Werner Müller-Warmuth zum 65. Geburtstag gewidmet The zeolites NaX, NaY, Zn(55)NaY, and Zn(74)NaY were investigated by means of carbon monoxide adsorption and with static and magic angle spinning (MAS) 23Na NMR spectroscopy. The Na+ distribution between the sodalite (/?)-and supercages of the fully hydrated zeolites NaX and NaY were found to agree with XRD results. In the hydrated zinc-exchanged zeolites the Na + ions almost exclusively populate the /?-cages. The adsorption isotherms of CO in the dehydrated zeolites were analyzed quantitatively to yield the concentrations of Na+ residing in the supercages. The measured static and MAS 23Na NMR spectra were analyzed by comparing their widths and shapes with simulated central transition patterns and yield, inter alia, the concentrations of Na+ associated with the spectrum components. Arguments are put forward that 23Na NMR of dehydrated zeolites is well suited to distinguish Na + cations in highly symmetric environments and mobile Na+ species from others located on general positions, but further resolution is hardly feasible. 
  Reference    Z. Naturforsch. 50a, 199—210 (1995); received October 17 1994 
  Published    1995 
  Keywords    23Na NMR, Adsorption, Carbon monoxide, Zeolites, Zinc-exchange 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0199.pdf 
 Identifier    ZNA-1995-50a-0199 
 Volume    50 
3Author    F. Ucun, A. Sağlam, F. Köksal, S. BahçeliRequires cookie*
 Title    An EPR Study of Mo 5+ Introduced into NaY Zeolites by Solid-State Reactions  
 Abstract    By means of an EPR investigation of Mo 5+ ions introduced into NaY zeolites by solid-state reactions, the location and coordination of Mo 5+ in zeolites were investigated. Two different locations, free and distorted tetrahedral, were found. The molecular orbital coefficient, ß 2 , and the effective charge, Q, for the MO 5+ ions in a distorted tetrahedral structure were calculated and interpreted. 
  Reference    Z. Naturforsch. 54a, 159—161 (1999); received December 2 1998 
  Published    1999 
  Keywords    EPR, Zeolite, Mo 5+, NaY 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0159.pdf 
 Identifier    ZNA-1999-54a-0159 
 Volume    54 
4Author    F. Ucun, F. KöksalRequires cookie*
 Title    An EPR Study on V0 2+ and Mn 2+ Ions in Some Zeolites  
 Abstract    The electron paramagnetic resonance (EPR) of hydrated V0S0 4 -3H 2 0 and MnCl 2 -2H 2 0, adsorbed on the synthetic zeolites 3A, 4A, 5A and 13X of pore diameters 0.3, 0.4, 0.5, and 1.0 nm, respectively, and the natural zeolites heulandite and clinoptilolite was investigated. The spectra indicated that the coordination structures are V0(H 2 0)5 + and Mn(H 2 0)g + , and that their EPR line widths vary with the pore diameters and the surface areas of the zeolites. The spectra of V0(H 2 0)5 + in natural zeolites at room temperature display an isotropic behavior and therefore indicate that the water ligands are mobile. The EPR spin Hamiltonian parameters, the molecule orbital constant ß* 2 , and the Fermi contact term K e[[ were determined and are discussed. The spectra of Mn(H 2 0)^ for narrow-pore zeolites indicate the existence of mobile and immobile water, whereas for wide-pore and natural zeolites they indicated the existence of only mobile water. The obtained Mn(H 2 Ö)g + spectra are discussed. 
  Reference    Z. Naturforsch. 51a, 23—26 (1996); received October 17 1995 
  Published    1996 
  Keywords    EPR, V0 2 +, Mn 2 +, Zeolites, Coordination 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0023.pdf 
 Identifier    ZNA-1996-51a-0023 
 Volume    51 
5Author    Fevzi Köksal, Fatih Ucun, İbrahim KartalRequires cookie*
 Title    EPR Study of Cr 5 + and Cu 2 + in Some Zeolites Introduced by Solid-and Liquid-State Reactions  
 Abstract    This study reports on the EPR of Cr 5+ and Cu 2+ ions, introduced by solid-and liquid-state reactions with the synthetic zeolites 3A, 4A and 5A, and the natural zeolite clinoptilolite. Cr 3+ was oxidized to Cr 5 + in the samples, the coordination around Cr 5 + being square pyramidal. Super-hyperfine (shf) interaction of Cr with 27 A1 nucleus was observed in both solid-and liquid-state-introduced 5A zeolite, whereas this shf could not be observed for the solid-state introduced 4A zeolite. The liquid-state Cr-introduced 4A zeolite needed a heat treatment at 473 K for Vi h for the appearance of shfs. Furthermore, it has been found that the coordination structure around the Cu 2 + is square pyramidal in solid-state introduced samples, whereas it is octahedral in the liquid-state introduced ones. 
  Reference    Z. Naturforsch. 51a, 242—244 (1996); received January 8 1996 
  Published    1996 
  Keywords    EPR, Cu 2 +, Cr 5 +, Zeolites, Ion introduction 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0242.pdf 
 Identifier    ZNA-1996-51a-0242 
 Volume    51 
6Author    F. Köksal, F. UcunRequires cookie*
 Title    EPR of 0 2 " Radicals in the Zeolites NH 4 NaY and NH 4 CaA  
 Abstract    Activated and non-activated states of the zeolites NH 4 NaY and NH 4 CaA, and their NH 4 forms were prepared with an (NH 4) 2 S0 4 solution and were investigated by EPR after 7-irradiation. The formed radicals were attributed to O-T supposed to be trapped near a trigonally coordinated framework of 27 A1 (I = 5/2). Anisotropic O^" spectra were observed, consisting of hyperfine structure due to the 27 Al framework, even at room temperature. This was attributed to the scarceness of NH 4 sites or trap sites because of the preparation of the NH 4 forms of the zeolites with an (NH 4) 2 S0 4 solution. The crystal field splittings were found and interpreted. 
  Reference    Z. Naturforsch. 53a, 951—954 (1998); received October 28 1998 
  Published    1998 
  Keywords    EPR, Zeolites, 0~, NH 4 NaY, NH 4 CaA 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0951.pdf 
 Identifier    ZNA-1998-53a-0951 
 Volume    53 
7Author    Masahiko Matsumiya, Ryuzo Takagi3Requires cookie*
 Title    Molecular Dynamics Study on the Adsorption Selectivity for Negative Elements in Aluminosilicates  
 Abstract    For the pyrochemical reprocessing o f spent metallic nuclear fuels in molten salt baths it is important to investigate the adsorption selectivity o f cations in aluminosilicates. A molecular dynamics simulation has been performed on sodalite and zeolite with exchangeable monovalent and multivalent cationic fission products at 673 K in order to calculate their self-diffusion coefficients in the aluminosilicate framework and estimate the selectivity o f the exchangeable cations. The results enables us to conclude that the self-diffusion coefficients of monovalent cations decrease with increasing ionic radius. The order of the adsorption selectivity is Li < K < Na < Cs in sodalite and Li < Na < K < Cs in zeolite. The self-diffusion coefficients of multivalent cations are almost independent o f the ionic radius, and these cations are in aluminosilicates more stable than monovalent cations. The results are consistent with the experimental results. 
  Reference    Z. Naturforsch. 56a, 459—165 (2001); received February 9 2001 
  Published    2001 
  Keywords    Adsorption Selectivity, Aluminosilicates Framework, Molecular Dynamics Simulation, Negative Elements, Self-diffusion Coefficient, Sodalite, Zeolite 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0459.pdf 
 Identifier    ZNA-2001-56a-0459 
 Volume    56