ISSN:
1573-1111
Keywords:
Synthesis
;
isomorphous substitution
;
XRD
;
ion exchange
;
catalytic activity
;
β-zeolite B and Ga isomorphs
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The crystalline isomorphs ofβ-zeolite containing boron or gallium in the framework positions have been synthesized and the products characterized by comparing them with Al-β zeolite. Evidence for the presence of B or Ga in the zeolite lattice framework has been confirmed by spectroscopic (XRD, IR and29Si,27Al and11B MASNMR), DTA/TG, ion exchange, sorption and catalytic activity results. Chemical analysis and NMR confirm the absence of any significant amount of Al in the zeolite (SiO2/Al2O3=2000). The XRD pattern of the as-synthesized B-β and Ga-β compounds matched well with that of Al-β zeolite. Lattice B and Ga leads to a change in the X-rayd values. Framework and bridging hydroxyl stretching IR bands ofβ-zeolite are shifted due to incorporation of gallium and boron into the zeolitic framework. MASNMR spectra of11B and29Si also suggest the presence of tetrahedrally coordinated B(III) or Ga(III) ions in theβ-zeolite framework. B and Gaβ-zeolites exhibit significant ion exchange capacity and catalytic activity in them-xylene isomerization reaction. The shifts in the IR bands towards higher frequency in B-β and lower frequency in Ga-β, the observed ion exchange capacities and catalytic properties, indicate the presence of B3+ or Ga3+ ions in the framework ofβ-zeolite.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00708767
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