INFLUENCE OF THE CONDITIONS OF PRELIMINARY HEAT TREATMENT ON THE MAGNETIC AND CATALYTIC PROPERTIES OF FE, NI / AL OXIDE SYSTEM IN THE REACTION OF CARBON DIOXIDE HYDROGENATION

Abstract

Fe, Ni- containing mono- and bimetallic catalysts based on Al₂O₃ were synthesized and tested in the methane hydrogenation reaction. The phase composition, magnetic and catalytic properties of mono-Fe(Ni)/γAl₂O₃ and bimetallic Fe-Ni/γ-Al₂O₃ oxide systems were studied, depending on the conditions of their pretreatment. Using the methods of X-ray diffractometry and electron magnetic resonance, it was established that the formation of magnetite and metallic nickel particles was determined, their concentration was determined depending on the preliminary reduction temperature in the hydrogen stream (300,400,500 ° C) of samples oxidized at 500 ° C in the air stream. It was shown that under conditions of CO₂ methanation (300–500 ° C), the catalyst contains nanosized particles of magnetite and nickel. A scheme of the CO₂ methanation reaction involving these particles is given. It was shown that the selection of the conditions of redox treatments allows to optimize the concentration and size of these particles, and thereby to regulate the activity of the catalyst and the yield of target products.