GB662392A - Manufacture of microspheroidal gel particles - Google Patents

Abstract

<PICT:0662392/III/1> <PICT:0662392/III/2> In the manufacture of microspheroidal inorganic oxide gel particles of e.g. silica, alumina, silica-alumina or silica-magnesia, by dispersing a hydrosol of the oxide in a substantially water-immiscible organic setting medium, e.g. acid treated lube oil stock, kerosene, butanol, carbon tetrachloride, ethylene dibromide or acetylene tetrabromide, a plurality of separate bodies of the setting medium are provided and the hydrosol is supplied successively to each of the bodies from one of two streams which subsequently rejoin to form a continuous loop, each of the streams being passed through a flow restriction orifice adapted to apply a pressure drop to the streams substantially greater than the normal pressure drop through either limb of the loop. The setting medium is heated and steam is injected into the hydrosol immediately prior to its entry into the setting medium so as to raise its temperature to, at least, that of the setting medium. The process is effected continuously by the several batch reactors being automatically operated on a fixed time cycle. The gels may be employed as catalysts or adsorbents. As applied to the manufacture of a silica-alumina gel, heated sodium silicate solution and a mineral acid, e.g. sulphuric acid, are mixed at 15 and the mixture fed with an aluminium salt solution to mixing tank 16. The so-formed hydrosol is fed from line 17 to the reactors 20, 21, 24, 25 in turn through a pipe loop, the limbs of which are provided with orifice plates 18, 19 so as to maintain a positive flow in each line no matter which of the reactors is being filled. Organic liquid is fed from storage tank 26, through heat-exchanger 28 and line 29 to the reactors, a bleed line 31 feeding small quantities of organic liquid through lines 32 to hydrosol inlet line 35 to prevent blockage during rest periods. Steam from line 36 is fed through lines 37 to mix with the hydrosol in line 35. Ammonia is fed to the reactors from lines 40, 41 to precipitate alumina. The reactors are discharged into an oil-water separator 46 from which oil overflows at 50 and is returned to storage tank 26 and the water-gel slurry is discharged at 53, washed on filter 54, reslurried and aged in tank 55, refiltered and washed on filter 57. The organic liquid in tank 26 is clarified by passing it through a heater 65, a drum 67 wherein water is flashed off and a filter 70. Means for breaking and separating the components of emulsions formed in separator 46 are denoted generally at 75, 76. The reactors are furnished with ammonia vents 42, air vents 44 and flush-water inlets 61.