Abstract:

FT-IR emission spectroscopy has been used to study the surface structure of V_2O_5/TiO_2 catalyst with V_2O_5 loadings of 0.4%, 2% and 10% wt. prepared by impregnation of TiO_2 in NH_4VO_3 solution. The IR emission spectra were recorded insitu durinbg the course of a calcination of the impregnated catalyst from 100 ℃ to 500 ℃. The ammonium vanadate supported on TiO_2 was found to be decomposition more easily than pure NH_4VO_3 most possibly owing to the chemical interaction between vanadate and TiO_2. For 10%. wt. V_2O_5/TiO_2 catalyst the IR peaks due to V_2O_5 phase appeared as the catalyst was calcined at 200—400 ℃. When the catalyst was calcined at 500 ℃ the peaks of V_2O_5 phase were evidently reduced indicating that the part of V_2O_5 phase decreased and a broad peak ranging from 1050 cm~(-1) to 900 cm~(-1) became prominednt especially after a calcination at 500 ℃. The broad peak was tentatively assigned to the highly dispersed VO_x species which might be the two-dimensional vanadium oxide. This study also demonstrated that FT-IR emission spectroscopy is a very sensitive technique for investigating the surface structure of metal oxide catalyst.

Key words: FT-IR emission spectroscopy, Catalyst characterization, V₂O₅/TiO₂, Surface structure