Abstract
The preparation of pelletized catalyst from the powdered raw materials is especially important in making solid catalysts for industrial use, and it is desirable from the practical point of view to elucidate the dependence of the mechanical strength of pellets on the pelletizing process. In the present study it is shown that the mechanical strength of zinc oxide-chromium oxide catalysts prepared by the extrusion process is dependent upon the water content in the paste and upon the amount of copper added to the paste, however the surface area and the pore size distribution of catalysts are dependent not so largely upon their strength as they might be in the case where alumina catalysts are prepared by the tabletting procedure.
Zinc oxide was mixed with the 30% water solution of chromium trioxide and the paste thus obtained was extruded following the addition of copper compound. After drying to reduce the water content in the pellet below 1%, the mechanical strength of pellets was measured by compressing them in the direction of their cylindrical axis, and by compressing them in the direction of their radius, and by subjecting them to tensile test.
From the results obtained it would be concluded that the measurements of the mechanical strength carried out by these three different methods show the deviations not to be so different from each other. It is clarified that the strength of ZnO-Cr2O3 catalysts depends upon the water content during the extrusion process, and that it is affected by the addition of copper and also by the reduction in the atmosphere where the catalysts are employed for industrial purposes.
