V.V. Kaichev

Preparation, active component and catalytic properties of supported vanadium catalysts in the reaction of formaldehyde oxidation to formic acid

Abstract The influence of the support nature was investigated with supported vanadium catalysts prepared by a wet impregnation method. SiO 2 , γ-Al 2 O 3 , ZrO 2 and TiO 2 (anatase) were used as supports. Two series of catalysts were prepared, the first one consisting of catalysts of composition ca. 20% wt. V 2 O 5 /80% wt. support (series 1) and the second one prepared by washing the series 1 samples with nitric acid (series 2). In the catalysts of series 1 (except 20% V 2 O 5 /80% SiO 2 ), vanadium is represented by both monolayer species (monomeric and polymeric VO x ) and crystalline V 2 O 5 phase. When vanadium is supported on SiO 2 , only the crystalline V 2 O 5 is formed. Washing the samples of series 1 with nitric acid removes crystalline V 2 O 5 phase. Monomeric and polymeric vanadia species are more active in the reaction of formaldehyde oxidation to formic acid as compared to V 2 O 5 .

The origin of self-sustained reaction-rate oscillations in the oxidation of methane over nickel: an operando XRD and mass spectrometry study

The self-sustained kinetic oscillations in the catalytic oxidation of methane over Ni foil have been studied at atmospheric pressure using an X-ray diffraction technique and mass spectrometry. It has been shown that the regular reaction-rate oscillations appear under oxygen-deficient conditions and the period of oscillations varies between approximately 200 and 4000 s. The operando measurements have revealed a higher activity of metallic Ni in the reaction than NiO oxide and have unambiguously showed that the oscillations arise due to the reversible bulk oxidation of Ni to NiO.