Kinetics of Kaolinite Dehydroxylation

When kaolinite is heated under pressures of self-generated H₂O vapor from 0.4 to 3.2 atm, the dehydroxylation is best described by a nucleation-and-growth equation with m varying from 1.10 to 2.16 as the pressure is increased. The temperature coefficient of the rate constant, expressed as an apparent activation energy, varies from 62.4 to 260 kcal/mol. The H₂O vapor evolved in a self-generated-atmosphere sample holder was automatically swept into a gas chromatograph at fixed intervals. The measurement is specific for H₂O.