| 摘要 |
<p>Prodn. of refractory alumina agglomerates (esp. for use as catalyst carriers) by partial dehydration of hydra gillite or aluminium oxide hydrate gel in a hot gas stream and subsequent autoclave treatment opt. in presence of an acid is improved by addition of 1-15 wt. % (pref. 2-7 wt.%) of an oxide(s) of La, Nd, Pr and/or Th (w.v.t. the weight of alumina) and firing the product at =1200 degrees C. The addition of the above metal oxide(s) improves the refractioness of alumina agglomerates (up to 1200 degrees C); their specific surface area decreases only slightly at high temps; they have high porosity and, yet, good mechanical strength (products derived from hydrargillite are supenion as far as the strength is concerned, whilst the products obtained from aluminium oxide hydrate gel have higher porosity; both have very high abrasion resistance). Alkali metal oxides are practically eliminated.</p> |
