Thermal Carbonation of Calcium Hydroxide

DOI

Bibliographic Information

Other Title
  • 水酸化カルシウムの加熱炭酸化

Description

The reaction process of Ca (OH) 2 with CO2 at high temperatures was examined by TGA, DTA, high temperature XRD and SEM. Two kinds of Ca (OH) 2, sample-A (ay. 0.5 μm in diameter, 0.1 μm in thickness, hexagonal plate) and sample-B (ay. 7 μm in diameter, 15 μm in thickness, hexagonal prism), were prepared by mixing a 1/2 mol/l KOH solution with a 1/4 mol/l CaCl2 solution under different conditions.<BR>The thermal carbonation occured in the following three steps : <BR>Step-1, between 250° and 300°C, was regarded as a surface reaction. This reaction made a little weight gain in TG curve and a small exothermic peak in DTA curve to finer particles like sample-A. The thickness of the CaCO3 layer after completion of this process was about 1.2 nm for sample-A.<BR>Step-2, between 300°C and dissociation temperatures of Ca (OH) 2, was regarded as a direct reaction of Ca (OH) 2 with CO2. The reaction rate for this process obeyed the following relation, [1- (1-α) 1/3] n =Kt. The n values for rate equation of sample-A and sample-B were 2 and 3 and the apparent activation energies for this process of sample-A and sample-B were 44.8 and 52.0 kcal/mol, respectively. This reaction would be the diffusion rate controlling process.<BR>Step-3, a reaction between CaO and CO2, occurred immediately after dissociation of Ca (OH) 2. This reaction was dominant at lower CO2 concentration or for larger particles like sample-B.

Journal

  • Gypsum & Lime

    Gypsum & Lime 1982 (178), 121-128, 1982

    The Society of Inorganic Materials, Japan

Details 詳細情報について

  • CRID
    1390282680366086784
  • NII Article ID
    130004011201
  • DOI
    10.11451/mukimate1953.1982.121
  • ISSN
    21854351
  • Data Source
    • JaLC
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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