| 摘要 |
<p>An alumina catalyst carrier contains 0.02-1% of boron oxide and has a porous volume due to pores of diameter from 0.1-8 microns of 5-20 cm.3 per 100 g., a specific surface less than 0.5 m.2/g., the carrier having been prepared by calcination at 1600-1800 DEG C. of a mixture of active alumina of specific area at least 20 m.2/g. together with 25 to 400% of its weight of a -alumina and the necessary proportion of boron oxide. The calcination may be effected in a tube furnace along which the alumina is passed in which case the quantity of boron oxide added to the initial charge is substantially equivalent to that present in the final product. Alternatively, if a static mass is heated in a furnace then the initial mixture should preferably contain from 0.1 to 5% of boron oxide. According to a typical example aluminum oxide of which not more than 80% is larger than 20 microns, the remainder being less than 60 microns is mixed with an equivalent quantity of active aluminium oxide obtained by pulverizing aluminium oxide trihydrate in a current of a hot gaseous mixture of air and hydrocarbons at about 700 DEG C. 0.05% of boric anhydride is added to the mixture which is then kneaded with water and granulated into 3 mm. balls which are dried at 1100 DEG C. before calcining at 1700 DEG C. for thirty minutes. The addition of boron oxide increases the porous volume and decreases the surface. The carriers obtained may be impregnated with metallic salts.</p> |
