title: In situ Raman studies during sulfidation, and operando Raman-GC during ammoxidation reaction using nickel-containing catalysts: a valuable tool to identify the transformations of catalytic species.
abstract: Ni-containing catalysts are investigated under reaction conditions for two different cases, during sulfidation, with Ni-Mo based catalysts, and during ammoxidation reaction, with the Ni-Nb catalysts. It is shown how Raman spectroscopy can follow some of the transformations of these catalysts upon different treatments. For the NiMo/Al(2)O(3)-SiO(2) system it was possible to identify some of the sulfided Mo species formed during the sulfidation of the oxide precursors, while for the bulk Ni-Nb oxide catalysts the simultaneous reaction-Raman results strongly suggest that the incipient interaction between niobium and nickel oxides at low Nb/Ni atomic ratios is directly related to catalytic activity, and that a larger size well-defined NiNb(2)O(6) mixed oxide phase is not active for this reaction. Moreover, the promotion by niobium doping appears to be limited to a moderate niobium loading. It was found that in situ and operando Raman are valuable techniques that allowed the identification of active Mo-S and Ni-Nb species under reaction conditions, and that are not stable under air atmospheres.
authors.affiliation: Catalytic Spectroscopy Laboratory, Instituto de Catálisis y Petroleoquímica (CSIC), Marie Curie, 2, E-28049-Madrid, Spain. oguerrero@uma.es
authors.forename: M Olga
authors.initials: MO
authors.lastname: Guerrero-Pérez
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Rojas
authors.forename: Aida
authors.initials: A
authors.lastname: Gutiérrez-Alejandre
authors.forename: Jorge
authors.initials: J
authors.lastname: Ramírez
authors.forename: Felipe
authors.initials: F
authors.lastname: Sánchez-Minero
authors.forename: César
authors.initials: C
authors.lastname: Fernández-Vargas
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Bañares