Rheology of Molding Materials for Extruding Billets to Obtain Copper-Containing Alumina-Silica Catalysts
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Vol. 61, No. 3, September, 2020
SCIENTIFIC RESEARCH AND DEVELOPMENT RHEOLOGY OF MOLDING MATERIALS FOR EXTRUDING BILLETS TO OBTAIN COPPER-CONTAINING ALUMINA-SILICA CATALYSTS V. I. Vanchurin,1,4 A. V. Belyakov,1,5 D. Sh. Dzhumamukhamedov,2 and A. V. Fedotov3 Translated from Novye Ogneupory, No. 5, pp. 23 – 28, May, 2020.
Original article submitted April 1, 2020. A ceramic copper-alumina-silica catalyst (CAS-C) for dehydrogenation of cyclohexanol to cyclohexanone in the process of carbamide production was used to study the rheological and mechanical properties of the copper-containing alumina-silica plastic material depending on its composition. The provided data characterize the effect of the process and design conditions of molding the material in a screw press on the performance of extruded ceramic billets. The uncovered specifics of the behavior of the molded plastic material are due to the differences in the surface properties of silica particles interacting with the precursor of the active ingredient during catalyst synthesis. A composition of the molding material and screw-press extrusion conditions were established to ensure the yield of high-quality, mechanically strong ceramic billets (extrudates). Keywords: copper-alumina-silica catalyst (CAS-C), alumina-silica plastic mixture, extrusion, structural and mechanical properties.
involves the use of special additives, which reduce friction between powder particles and the walls of the mold during pressing, but remain inside the billets after a low-temperature heat treatment at 270 – 280°C and, thus, reduce their quality. The use of a less costly and more productive extrusion technique as part of the catalyst carrier production technology can provide significant advantages over the semi-dry pressing method. To ensure successful molding using screw extruders without evacuation, the plastic molding material should have a certain set of structural and mechanical properties and be adapted to the technological and design conditions of the extrusion process. With regard to the copper-containing alumina-silica plastic molding materials for producing copper-containing catalysts, the literature contains little data concerning the effect of their composition on the molding properties and successful extrusion conditions. The objective of this work is to study the structural and mechanical properties of alumina-silica plastic molding materials by varying their composition within the range that does not adversely affect the operating characteristics of the finished catalyst. The authors also studied the effect of the design features of the ceramic press molding unit and extrusion parameters on the quality of resulting billets.
INTRODUCTION There are two main methods for obtaining a ceramic carrier for producing catalysts: palletization of finely ground powder mixtures and extrusion molding of plastic molding materials. Producing pellets using a semi-dry pressing technique makes it possible to obtain ceramic billets of strictly defined geometry and high mechanical strengt
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