Selective oxidation of ethane: Developing an orthorhombic phase in Mo-V-X (X=Nb,Sb,Te) mixed oxides

P. BOTELLA; A. DEJOZ; M. C. ABELLO; M. I. VÁZQUEZ; L. ARRÚA; J. M. LÓPEZ NIETO

CATALYSIS TODAY

Elsevier

Año: 2008

0920-5861

Mo –V –X (X =Nb, Sb and/or Te) mixed oxides have been prepared by hydrothermal synthesis and heat-treated in N2 at 450 ºC or 600 ºC for 2 h. The calcination temperature and the presence or absence of Nb determines the nature of crystalline phases in the catalyst. Nb-containing catalysts heat-treated at 450 ºC are mostly amorphous solids, while Nb-free catalysts heat-treated at 450 ºC and samples treated at 600 ºC clearly contain crystalline phases.TPR-H2 experiments show higher H2-consumption on catalysts with amorphous phases. Catalytic results in the oxidative dehydrogenation of ethane indicate that the selective production of the ole .n is strongly related to the development of the orthorhombic Te2M20O57 or (SbO)2M20O56 (M =Mo, V, Nb) phase (the so-called M1 phase),which is mainly formed at 600 ºC This active and selective crystalline phase is characterized to show moderate reducibility and active centers enough for the selective oxidative activation of ethane with the minimum quantity possible of active centers for ethylene activation. In this sense, the best yield to ethylene has been achieved on a Mo –V –Te –Nb mixed oxide.