Reaction of Ca(OH)2 with HCl in the presence of water vapour at low temperatures

The final products of the reaction between HCl and Ca(OH)2 can be Ca(OH)Cl, CaCl2, or both simultaneously depending on the temperature, HCl concentration and reaction time. A possible mechanistic pathway consistent with the experimental results concerns two consecutive reactions: The formation of Ca(OH)Cl and the final formation of CaCl2 from the reaction of Ca(OH)Cl with HCl. However, the second reaction might take place only, when Ca(OH)2 is missing. The amount of water retained by the solid during the reaction between HCl and Ca(OH)2 reaction is determined at 120 °C and 18% relative humidity employing a thermogravimetric analyser. The amount of water retained is a measure for the tendency of the solid to agglomerate. The stability of the Ca(OH)Cl at ambient conditions is studied and found to be good.