GB850893A - Improvements in or relating to aluminium oxide carriers for catalysts and to catalysts incorporating such carriers - Google Patents

Abstract

Alumina consisting predominantly of a mixture of alumina mono-hydrate and amorphous alumina is activated by calcining at 450-850 DEG C., treating with acid in a manner such that at least 1% and at most 20% of the activated alumina is dissolved, washing, drying, and re-calcining at 500-850 DEG C., the alumina being shaped in the form of tablets, beads, granules, or the like before the acid treatment. A reforming catalyst consists of the activated alumina carrying a compound, e.g. the chloride or fluoride, of an element of Group VIII of the Periodic Table, which may be further treated with hydrogen sulphide or ammonium sulphide, and a hydrogenating and/or desulphurising catalyst consists of the activated alumina containing the oxide or sulphide of molybdenum, tungsten, or vanadium. The acid treatment may be carried out in such manner that at least 3% and not more than 15% of the alumina is dissolved. The acid may be dilute hydrochloric acid, nitric acid, or a mixture of the two, and the acid treatment may be effected at 50 DEG C. In Example 1, a gelatinous precipitate is formed by adding aluminium amalgam to dilute acetic acid, separating off mercury, and adding ammonia. The precipitate is dried at 200 DEG C. and ground. One part is calcined at 760 DEG C., another part at 600 DEG C., and a third at 700 DEG C., and the parts are formed into cylindrical tablets. Some of each part is treated with hydrochloric acid, washed, dried, and calcined for 2 1/2 hours at 750 DEG C. to provide three modified types. The six aluminas are impregnated with a solution of chloroplatinic acid and hydrochloric acid, dried, and ignited at 540 DEG C., and the compacted bulk density and volume activity with reference to a mixture of hydrogen and a paraffinic oil cut are determined. Data are given as to the surface area, pore volume, and pore size distribution of the six types of activated alumina. In Example 2, the original three aluminas are calcined for 1 hour at 780 DEG C. and then portions are subjected to the acid treatment and the treatment with the chloroplatinic acid solution of Example 1, and similar data are furnished. In Example 3, four tabletted samples of the alumina of Example 1 are calcined for 1 hour at 500 DEG C., 650 DEG C., 780 DEG C., and 850 DEG C. respectively, and each are treated with dilute hydrochloric acid at 70 DEG C., washed, dried, and calcined for 3 1/2 hours at 750 DEG C. After treatment with chloroplatinic acid as in Example 1, similar data are obtained. In Example 4, the second calcined alumina of Example 2 (A 2) is treated with five different concentrations of hydrochloric acid at 50 DEG C., washed, dried, and calcined for 1 hour at 750 DEG C. Similar data are given for platinum-containing catalysts prepared from the five samples. In Example 5, alumina A 2 is treated with various quantities of hydrochloric acid of more slightly varying concentration, and similar data are given for the final platinum-containing catalysts. In Example 6, alumina A 2 is treated with dilute hydrochloric acid, washed, and dried, and is divided into five equal parts which are calcined for 3 hours at different specified temperatures ranging from 540-840 DEG C. Data are given for the platinised samples. In Example 7, alumina granules are calcined at 650 DEG C., extracted with dilute nitric acid, washed, dried, calcined at 600 DEG C., impregnated with a solution containing MoO3, CoO, and ammonia, dried, and calcined at 650 DEG C. A comparison is made as a hydrodesulphurisation catalyst with a catalyst prepared by impregnating aluminium hydroxide powder with a similar solution, drying, tabletting, and calcining. In Example 8, part of an activated alumina in the form of cylindrical tablets is treated with hydrochloric acid, washed, dried, and calcined for 10 hours at 780 DEG C. The original and treated aluminas are impregnated with a solution of palladium chloride and hydrochloric acid, dried, and calcined for 1 hour at 540 DEG C. Data are given for the two palladium-containing aluminas.