NEW INTERMEDIATE PHASES IN FORMATION AT V-MG-O CATALYST

The simulation of the active phase formation process at the V-Mg-O cat alyst has been carried out using as a precursor, magnesium orthovanada te pretreated at different temperatures. Two intermediate phases of di fferent structures were discovered and separated. X-ray diffraction, e lectron microscopy, chemical and thermogravimetric analyses and IR and Raman spectroscopies were used for the identification of both phases. The orthovanadate was found to be the final active product formed by the wet method of the synthesis. The catalytic activity of these new p hases in the oxidative dehydrogenation of ethylbenzene to styrene was studied and compared to those of the supported V-Mg-O catalyst. (C) 19 98 Elsevier Science B.V. All rights reserved.