T. V. Andrushkevich

Catalytic properties of the vanadium-molybdenum oxide system for acrolein oxidation

The catalytic properties and phase composition of the silica-supported vanadium-molybdenum oxide system have been studied in acrolein oxidation. The active component of the catalyst is the compound VMo3O11+x, whose maximum content is observed in the compositions range of 10–15 mol.% V2O5 −90–95 mol.% MoO3.AbstractВ реакции окисления акролеина исследованы каталитичечкие свойства и фазовый состав ванадиймолибденокисной системы, нанесенной на SiO2. Активным компонентом катализатора является химическое соединение VMo3O11+x, максимальное содержание которого наблюдается в области составов 10–15 мол.% V2O5÷90–85 мол.% MoO3.

Determination of surface intermediates during the selective oxidation of formaldehyde over V–Ti–O catalyst by in situ FTIR spectroscopy

Abstract Formaldehyde oxidation to formic acid on V–Ti–O catalyst was studied in a flow-circuit setup with a differential reactor and in the IR cell. Surface intermediates leading to formic acid formation were identified. Catalyst calcination temperature was varied to study its effect on catalyst performance and surface species structure.

Catalytic properties of V−Mo−O systems in acrolein oxidation

Catalytic properties of V−Mo−O systems have been studied in acrolein oxidation. When catalysts are activated in reaction mixtures at 673 K, then a solid solution of molybdenum oxides in reduced vanadium oxides is formed, which is responsible for deep oxidation. Also, several compounds are produced, which by their activity and selectivity to acrylic acid formation are arranged in the sequences VMo3O11≅VMo2O8+x>V6Mo4O25, and VMo3O11>VMo2O8+x≫V6Mo4O25, respectively.AbstractВ реакции окисления акролеина исследована V−Mo−O система. При формировании катализаторов при 673 K в реакционной смеси в системе образуются твердый раствор оксидов молибдена в восстановленных оксидах ванадия, который катализирует в основном глубокое окисление, и ряд химических соединений, которые по активности располагаются в ряд: VMo3O11≈VMo2O8+x>V6Mo4O25, а по селективности в реакции образования акриловой кислоты: VMo3O11>VMo2O8+x≫V6Mo4O25.

Formation of active component of MoVTeNb oxide catalyst for selective oxidation and ammoxidation of propane and ethane

Abstract The effect of slurry pH on the formation of active component of MoVTeNbO catalyst for selective (amm)oxidation of ethane and propane has been studied. pH affects the nature and composition of the crude and dry precursors as well as chemical and phase composition of the final catalyst. The most effective catalyst is prepared at pH = 3.0, which is characterized by a maximum content of M1 phase.

Calorimetric study of the oxygen bond energy in a binary V−Ti catalyst and individual vanadium and titanium oxides

Bond energy of oxygen in a binary V−Ti catalyst and individual V and Ti oxides has been studied by the calorimetric method. The samples studied were shown to be significantly different in bond energy, homogeneity of surface oxygen and mobility of the bulk one. Vanadium and titanium oxides appeared to interact in the binary system to form an active surface with redox properties very different from those of the individual oxides.

IR SPECTRA OF INDIVIDUAL COMPOUNDS FORMED IN V-Mo-O SYSTEMS UNDER CATALYTIC OXIDATION OF ACROLEIN

IR spectra have been obtained for the compounds formed in V−Mo−O and V−Mo−O/SiO2 catalysts after their treatment by the reaction mixture. According to X-ray phase analysis data, IR spectra for individual compounds have been identified. Spectra of VMo3O11 are discussed.AbstractПолучены ИК-спектры соединений, образующихся в V−Mo−O и V−Mo−O/SiO2 катализаторах после обработки реакционной смесью. На основе данных рентгенофазового анализа выявлены ИК-спектры индивидуальных соединений. Обсуждено спектральное проявление соединения VMo3O11.

Adsorption heats of acrolein and acrylic acid on promoted V−Mo−O catalysts

Adsorption heats of acrolein and acrylic acid on promoted V−Mo−O catalysts for selective oxidation of acrolein have been measured by the calorimetric technique. It has been established that modification changes the energy characteristics of the interaction of acrolein and acrylic acid with catalyst surface.AbstractКалориметрическим методом измерены теплоты адсорбции акролеина и акриловой кислоты на промотированных ванадий-молибденоксидных катализаторах селективного окисления акролеина. Показано, что модифицирование приводит к изменению энергетики взаимодействия акролеина и акриловой кислоты с поверхностью катализаторов.

INFLUENCE OF WATER VAPOR ON PROPYLENE OXIDATION ON VMo CATALYST

The dependence of reaction rates for acetone and acetic acid formation on the concentration of water vapor is determined on the basis of the participation of surface hydroxy groups and Brönsted acid centers of the catalyst.AbstractЗависимость скоростей реакции образования ацетона и уксусной кислоты от концентрации водяных паров обусловлена участием гидроксильных групп и бренстедовских кислых центров поверхности катализатора.

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 .

IR spectroscopic studies of surface acrolein and acrylic acid compounds in conditions of catalytic oxidation of acrolein on V−Mo−Si−O catalyst

Three surface complexes of acrolein have been identified by high-temperature IR spectroscopic method. Their extinction coefficients have been decermined.AbstractМетодом выцокотемпературной ИК-спектроскопии идентифицированы три поверхноцтных комплекса акролеина и определены их коэффициенты экстинкции.