Temperature-programmed reduction studies of V-Ag catalysts

In H-2/N-2 atmosphere, the reduction behavior of V-Ag catalysts with V/Ag atomic ratios 1/0, 9/1, 3/1, 2.16/1, 1.5/1, 1/1, and 0/1 were studied by temperature-programmed reduction (TPR), S-ray diffraction (XRD), and ultraviolet diffuse reflectance spectra (UVDRS), The results showed that the reduction processes of Ag2V4O11, Ag2V4O10.84, and Ag1.2V3O8 are all the same while the reduction temperature was raised; they were first reduced to Ag and V6O13, then to VO2, and thence to V2O3 subsequently. To vanadium oxides in V-Ag catalysts, the reactions with hydrogen were accelerated and the peak temperatures (T-M) of TPR were decreased explicitly due to the addition of silver element. (C) 1998 Academic Press.