| 摘要 |
<p>SiO2-Al2O3 microspheres are prepd. by (a) acidifying an aq. alkali metal silicate soln. with a strong mineral acid (I) and a weak organic acid (II), concn. of (I) being such as to provide an acid/alkali metal ratio of 0.75-1.0 and concn. of (II) being such as to increase this ratio by a factor of 1.3-2, (b) mixing with an acidic Al2O3 sol. and sufficient urea to effect 150-250% neutralisation of the acid anion content on hydrolysis of the urea to NH3, (c) dispersing the mixt. as droplets in a hot oil bath to form spheroidal hydrogel particles, (d) ageing the particles in the hot oil and (e) washing, drying and calcining. For use as a catalyst (support) in a fixed bed-type operation. Method ensures that firm hydrogel particles are formed which will retain their structural integrity during further processing.</p> |
