Chlorine dehydroxylation in plate-like silica gels prepared by hydrolysis of Si(OCH3)(4) was investigated for gels treated in chlorine at 800 degrees C. The infrared absorption spectrum of OH on the open pore surface of the gel was measured. The exchange reaction between OH and Cl was found to decrease linearly with the square root of treatment time and with reciprocal gel thickness. The dependence of the dehydroxylation rate on gel thickness indicated that the exchange between OH and Cl is limited by Cl-2 diffusion into the gel. (C) 1997 Elsevier Science B.V.
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