III International Conference

PP-II-1133. Results and discussionThe BET surface areas of the supported vanadium oxide catalysts and their correspondingsurface vanadia densities (V/nm 2 ), and catalytic properties are presented in a Table. VSi andVAl catalysts present the mixture of phases of V 2 O 5 and support (SiO 2 и γ-Al 2 O 3,accordingly). VTi catalysts presents phase of anatase, modified by vanadia, and only smallamounts of crystalline phase of V 2 O 5 .HCOOCH 3 was shown to be the main reaction product over γ-Al 2 O 3 and TiO 2 . SiO 2 isinactive in formaldehyde oxidation.Formic acid was shown to be the main product of formaldehyde oxidation under V 2 O 5 ,VTi and VSi samples. HCOOCH 3 and formic acid were the products of formaldehydeoxidation over VAl sample.Table. Catalytic properties of the V 2 O 5 and supported vanadium catalysts.Catalyst Phase S,m 2 /g V/nm 2 , t, s X, %S, %r*10 -16 ,composition%HCOOH HCOOCH 3 CO x molec/atomV*sV 2 O 5 V 2 O 5 5 - 2.8 4.6 91.8 6.8 3.1 0.04VSi V 2 O 5 , SiO 2 129 10.1 1.3 6.6 81.7 18.3 - 0.64VAl V 2 O 5 ,VTiγ-Al 2 O 3Anatase,V 2 O 5 traces183 10.7 1.5 18.7 48.2 49.1 2.7 1.0494 14.0 0.3 34.6 96.2 1.3 2.5 17.8t,s – the contact time; X – conversion ; S – selectivity; r – the reaction rate. .The following row of catalytic activity in reaction of formaldehyde oxidation wasdetermined: VTi >> VAl > VSi > V 2 O 5 . The highest activity of VTi catalysts was obtaineddue to chemical interaction of vanadium with TiO 2 contrary to SiO 2 and γ-Al 2 O 3 .The interaction of formaldehyde and its oxidation products (i.e. formic acid and methylformate) was studied by in situ FT-IR spectroscopy. Bidentate formates form duringformaldehyde oxidation. The same formats form during formic acid adsorption on all studiedsupported vanadium catalysts. The effect of the support on the rate of formats decompositionand on bond strength of bidentate formates with vanadium sites was displayed.On the base of constants rates of formate decomposition the row of stability ones my bepresented: VAl > VTi >VSi. The effect bond strength on direction of formaldehydeconversion is observed.AcknowledgementThe work was supported by the Russian Foundation for Basic Research, Grant 06-03-08137-ofs and Grant 06-03-32473.372