Catalytic properties of crystalline titanium silicalites. 1. Synthesis and characterization of titanium-rich zeolites with MFI structure

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90086-J· OSTI ID:5405120

Thangaraj, A; Kumar, R; Mirajkar, S P; Ratnasamy, P ^[1]

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1. National Chemical Lab., Pune (India)

Crystalline titanium silicalites with the MFI structure and high titanium content (Si/Ti{double bond}10) have been prepared using improved synthesis procedures. The monoclinic lattice symmetry of silicalite-1 changes to orthorhombic on introduction of titanium. The titanium silicalites retain their orthorhombic symmetry even after calcination in air. On progressive incorporation of titanium, (1) the unit cell dimensions and volume (from XRD) increase linearly, (2) the crystal size decreases progressively, (3) the intensity of the framework IR band at 960 cm{sup {minus}1} increases, (4) a band around 47,000 c{sup {minus}1} appears in the electronic spectra due to charge transfer transitions involving Ti(IV) sites, (5) the hydrophilicity of the zeolite (from water adsorptions measurements) increases, (6) the adsorption capacity for cyclohexane increases, (7) the {sup 29}Si MAS NMR lines exhibit progressive broadening, and finally (8) the catalytic activity in the hydroxylation of phenol to catechol and hydroquinone also increases markedly. Based on these observations, it is concluded that a significant fraction of titanium in these samples is situated in framework positions. The catalytic properties of these well-defined titanium-modified zeolites will be described in more detail in the subsequent parts of this series.

• OSTI ID: 5405120
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 130:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
AIR
ALKANES
AROMATICS
CALCINATION
CATALYSTS
CATALYTIC EFFECTS
CHARGE TRANSPORT
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
CYCLOALKANES
CYCLOHEXANE
DECOMPOSITION
DEVELOPERS
DIFFRACTION
ELEMENTS
EVEN-ODD NUCLEI
FLUIDS
GASES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
HYDROXYLATION
INFRARED SPECTRA
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
METALS
MINERALS
MORPHOLOGICAL CHANGES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
PHENOL
PHENOLS
POLYPHENOLS
PYROCATECHOL
PYROLYSIS
QUINONES
RESONANCE
SCATTERING
SILICON 29
SILICON ISOTOPES
SORPTION
SPECTRA
STABLE ISOTOPES
SYNTHESIS
THERMOCHEMICAL PROCESSES
TITANIUM
TRANSITION ELEMENTS
WATER
X-RAY DIFFRACTION
ZEOLITES