| 摘要 |
<p>1,245,654. Alumina extrudates. KONINKLIJKE ZWAVELZUURFABRIEKEN V/H KETJEN N.V. 17 Sept., 1968 [4 Oct., 1967], No. 44115/68. Heading C1A. [Also in Division B1 Alumina extrudates are calcined for at least 1 hour at 450-850‹ C., wetted with water suitably in an amount of between 50 and 100% wt. calculated on the weight of calcined extrudate, and then subjected to attrition treatment, dried and calcined in order to increase the abrasion resistance of the alumina. The attrition treatment may comprise a tumbling of the calcined extrudates in the drum of a concrete mixer rotating at 60-80 r.p.m. or may comprise a vibrational treatment in a closed container at a frequency of 20-1000 vibs./min. The attrition treatment normally lasts at least 10 minutes and is continued until between 0À2 and 1% wt. Al 2 O 3 has been removed. The tumbled or vibrated extrudates may be treated with a mineral acid, e.g. HCl, to dissolve 3-5% wt. Al 2 O 3 before the drying and calcining steps. Alumina extrudates of the present invention may be impregnated with platinum salts, dried and calcined to form catalysts. Alternatively, an activated alumina extrudate may be impregnated with platinium salts, dried and calcined and then treated by the method described above.</p> |
