NMR studies of catalysts: Phosphorous-31 and vanadium-51 in vanadium-phosphorous-oxygen selective oxidation catalysts and the selective averaging of the second order quadrupolar interaction in aluminosilicates

Technical Report · Mon Jun 01 04:00:00 EDT 1987

OSTI ID:6368534

Walker, R D

Results of EPR and /sup 31/P and /sup 51/V NMR experiments on vanadium-phosphorous-oxygen catalysts revealed the presence of V(III) as well as the expected V(IV) and V(V). Preparations known to be highly oxidized,l such as ..beta..-VOPO/sub 4/ and B phase catalyst with P/V = 0.9, yielded NMR spectra showing only small effects of unpaired electron spin, and the EPR spin count indicated a correspondingly low concentration of V(IV). On the other hand, catalysts known to be highly reduced, such as butane-treated (VO)/sub 2/P/sub 2/O/sub 7/ and B phase catalysts with P/V = 1.0, 1.1, gave NMR spectra with strong effects of unpaired electron spin but low EPR spin counts. Since EPR will routinely detect V(IV) but not V(III) (and no unpaired electron spins are associated with V(V)), the strong paramagnetic effects observed in the reduced catalysts must result from V(III). The catalysts examined included the model compounds ..beta..-VOPO/sub 4/ and (VO)/sub 2/P/sub 2/O/sub 7/ before and after butane and butene treatment, precatalysts (P/V = 0.9, 1.0, 1.1) and B phase catalysts (P/V = 0.9, 1.0, 1.1) before and after butane treatment. The line broadening effects of the second-order quadrupolar interaction cause loss of resolution in the NMR spectra of interesting systems, such as /sup 27/Al in zeolites. A multiple pulse sequence proposed to selectively average the effects of the second-order quadrupolar interaction was investigated.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6368534
• Report Number(s): IS-T-1199; ON: DE87010931
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603 -- Materials-- Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BUTANE
BUTENES
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
ELECTRON SPIN RESONANCE
HYDROCARBONS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIGHT NUCLEI
LINE BROADENING
MAGNETIC RESONANCE
MULTIPOLES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS OXIDES
QUADRUPOLES
RESONANCE
SILICATES
SILICON COMPOUNDS
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
VANADIUM 51
VANADIUM COMPOUNDS
VANADIUM ISOTOPES
VANADIUM OXIDES