Synthesis and Application of Manganese Oxide Catalysts in Oxidation and Hydrogenation Processes

Abstract

The analysis is made of the results of performed investigations: elaboration and study of physical-chemical properties of the catalysts on the basis of manganese oxides and on their use in various fields of chemical industry. Physical-chemical and technological foundations of the formation of oxide-manganese catalyst-absorbent of new-type are validated. It has been shown that for processes of purification of combustible gases from H2S and organic sulphur compounds he most favorable thermodynamic and kinetical conditions are created at manganese catalyst the composition of which near to Mn3O4. This type of the catalyst, together with MnO2 and, partially with Mn2O3, hold a firm own place in the catalytic processes. The direction, associated with the use of modified alumooxide carrier for elaboration of oxide-manganese and metallic catalysts (Pt, Pd) became as the new and prospective in the technology of carriers and catalysts, used in the processes of oxidation and hydrogenation. Technological modes, realized in given method, provide to activate solid-phase reaction of the formation of calcium aluminates at lower temperatures, as well as to stabilize surface-structural characteristics and to enhance thermal stability and mechanical strength of modified carrier. In the technology of the catalysts of aluminium oxide, by the use, of the carrier, preliminary modified by calcium oxide, the Mn-Pd catalyst was elaborated available for oxidation of CO and hydrocarbons of spent gases of the motor transport. The addition of palladium to the oxide-manganese catalyst leads to the formation of new centers on the surface which are active in the reaction of CO oxidation. The processes of the formation of manganese catalysts in reaction medium were studied. The method for preparing of the Mn-Pd catalyst includes processing the samples with an ammonia water solution. Treatment of the catalyst with ammonia water causes the formation of a palladium ammonia complex, which decomposes witha formation of palladium black. It can be concluded that the treatment with ammonia water leads to the completion of the formation of the active surface of the catalyst and to the temperature decrease of complete oxidation of CO. The experience of industrial operation of catalysts on the basis of modified alumocalcium carriers has shown that by duration of efficient operation of reburning of discharged gases of the engines of internal combustion they may compete with well-known industrial marks of the catalysts.