Patent ID: 7671124

Claim:
A method of producing hydrotalcite of formula: [(Mg) x (Zn) y ] 1−z (Al) z (OH) 2 (A n− ) z/n .mH 2 O, wherein A n− represents an anion having a valence of n; x, y, z and m are values which satisfy the following expressions, 0.5≦x≦1, 0≦y≦0.5, x+y=1, 0.1≦z≦0.5, and 0≦m<1, the method comprising the steps of: providing a slurry of hydrotalcite, wherein the hydrotalcite slurry is obtained using magnesium sulfate as the magnesium source; and washing the slurry with water, wherein said hydrotalcite slurry is obtained by combining magnesium sulfate, aluminum sulfate, sodium hydroxide, and sodium carbonate, and optionally zinc sulfate; and subjecting the combination to a hydrothermal synthesis at a temperature of 120° to 250° C.; and further wherein the hydrotalcite has a sodium content of 100 ppm or less and a specific surface area of 1 to 40 m 2 /g.