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6910491 
Journal Article 
X-ray photoelectron spectroscopic characterization of the acetylene cyclotrimerization catalyst NbCl2(C (n) H (n) ) (n=10-12) 
Il'in, EG; Parshakov, AS; Teterin, AYu; Maslakov, KI; Teterin, YuA; , 
2011 
1 
Russian Journal of Inorganic Chemistry
ISSN: 0036-0236
EISSN: 1531-8613 
MAIK NAUKA/INTERPERIODICA/SPRINGER 
NEW YORK 
1788-1793 
WOS:000297619600019 
The elemental and ionic compositions of the surface of NbCl2(C (n) H (n) ) (n = 10-12), an active catalyst for acetylene cyclotrimerization into benzene, have been determined by X-ray photoelectron spectroscopy. Binding energy data for the sample sputtered with argon ions E (b) (Nb3d (5/2)) = 203.8-204.2 eV) suggest that the oxidation state of niobium in the active catalyst is +2 or +3. The narrow C1s line indicates the equivalence of all carbon atoms, and the corresponding binding energy, E b(C1s) = 284.0 eV, is close to the BE value for cyclic unsaturated hydrocarbons with conjugate double bonds. Interacting with atmospheric oxygen and moisture during sample preparation, niobium ions on the catalyst surface oxidize to their highest oxidation state, +5, characterized by E (b) (Nb3d (5/2)) = 207.3-207.7 eV. These data suggest that niobium oxychlorides or oxides form ion the sample surface. The catalyst is stable in a high vacuum and undergoes slight charging under the action of an X-ray beam, showing poor dielectric properties.