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

• Published in: Physical chemistry chemical physics : PCCP 2011-05, Vol.13 (20), p.9260-9267
• Main Authors: GUERRERO-PEREZ, M. Olga, ROJAS, Elizabeth, GUTIERREZ-ALEJANDRE, Aida, RAMIREZ, Jorge, SANCHEZ-MINERO, Felipe, FERNANDEZ-VARGAS, Cesar, BANARES, Miguel A
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Chemistry; Exact sciences and technology; General and physical chemistry; Nickel; Nickel oxides; Niobium; Oxides; Promotion; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Transformations
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c0cp02242j

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.