Evidence of lanthanum–chromium mixed oxides formed in CrOx/La2O3 model catalysts

CrOx/La2O3 mixed oxides, prepared by impregnating La2O3 with appropriate aqueous solutions of (NH4)2CrO4 and calcining at 600 °C for 4 h, have been investigated by means of XRD, TPR, XPS, DRIFTS, and Raman spectroscopy (RS). The formation of the compounds La2CrO6, La(OH)CrO4 and LaCrO4 under these conditions was evidenced. Strong peaks at 864, 884, 913, and 921 cm−1, as well as weak peaks at 136, 180, 354, 370, and 388 cm−1 in the RS spectrum of CrOx/La2O3 have been assigned to La2CrO6.