Oxidative dehydrogenation of n-butane over alkali and alkaline earth-promoted alpha-NiMoO4 catalysts

• Type: Article in International Scientific Journal
• Date: 1997

Authors

Luis Madeira (Author) Other; MartinAranda, RM (Author) Other; MaldonadoHodar, FJ (Author) Other; Fierro, JLG (Author) Other; Portela, MF (Author) Other

Journal

Title: Journal of Catalysis

Vol. 169 No. 2

Pages: 469-479

ISSN: 0021-9517

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 30 Citations

Scopus - 34 Citations

Other information

Authenticus ID: P-001-B24

DOI: 10.1006/jcat.1997.1714

Abstract (EN): Alpha phase of NiMoO4 promoted with alkaline (K and Cs) and alkaline earth (Ca, Sr, and Ba) metals has been studied for the oxidative dehydrogenation of butane. The catalysts were characterized by BET; X-ray diffraction; atomic absorption; inductively coupled plasma spectroscopy; Fourier transform infrared and Raman, X-ray photoelectron, and ultraviolet-visible diffuse-reflectance spectroscopic techniques; and CO2 temperature-programmed desorption. The molybdate structure remains intact after doping, However, while for the Ca-, Sr-, and Ba-doped catalysts, new species were detected as oxide and peroxide compounds, only traces of alkali metals were found in the bulk of the catalysts, for the same loadings of promoter. For both catalyst series, rate of butane conversion decreases with increasing promoter content and also with increasing ionic radius of the promoter element. A decrease of surface area accounts for this trend. Catalyst surface basicity and selectivity to dehydrogenation products appear to be closely related. In fact, increased selectivity to C-4 products has been observed upon promoter incorporation, specially for K and Cs. An overdoping effect was detected for barium-doped catalysts which exhibits a maximum of basicity at 9% promoter loading. Higher levels of promoter seem to decrease the surface basicity and the C-4's selectivity. At such Ba contents the formation of three-dimensional barium compound crystallites occurs, decreasing the amount of adsorbed CO2. Alkaline earth-promoted NiMoO4 appeared to be very promising catalysts for butadiene formation, being almost twice more selective to butadiene than the undoped counterpart, for the same conversion. (C) 1997 Academic Press.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11