PURPOSE: A specific calcium silicate is contacted with a mineral acid to extract calcium component, thereby to provide a highly oil-absorbing, petal-type silica having similar configulation to calcium silicate. The so formed silica is useful as adsorbent, catalyst carrier, formed body, etc.
CONSTITUTION: Calcium silicate of the formula, wherein n and m are positive inrtegers, and n is 0.1 to 10, which is obtained by hydrothermal reaction of water soluble silicate and water soluble calcium compound at 150 to 250°C is contacted with mineral acid to extract calcium component. Such process provides an average diameter 0.1 to 30μ, 0.005 to 0.1μ thick, petal-type silica having configuration similar to parent calcium silicate. As mineral acid, HCl, HNO3, H3PO4, etc are effectively used in concentration of pH 4 or less, or preferably, pH 1.3 to 3.0. The reaction temperature is in the range of 10 to 100°C, generally room temperature being sufficient. The reaction time of 30 minutes to 3 hours are satisfactory.
WATANABE YOSHIAKI
TAGA GENJI
