Dehydration Rate Measurements for tertiary-Butanol in a Variable Pressure Flow Reactor

Fundamentally, the dehydration reaction of tertiary-butanol is frequently used as an internal standard for relative rate studies of other decomposition reactions. We report here a study using radical trappers to isolate this path in tertiary-butanol pyrolysis experiments conducted in the Princeton variable pressure flow reactor between 658 and 980 K. A novel technique that determines the rate constant value by applying a global least-squares fit incorporating all experimental species (tertiary-butanol, isobutene, and water) evolution data is developed and applied to yield six rate constant values at two reaction pressures (6.1 and 18 atm) and at temperatures between 949 and 980 K. Data from previously reported studies are reanalyzed to evaluate their "absolute" uncertainties, and new Arrhenius parameters are derived based upon the present and previous measurements. The recommended rate constant (uncertainties) for the dehydration reaction is k = 2.88(0.91) × 107T2.21(0.10) s–1 exp(−62.4(0.9) kcal mol–1/RT). The new correlation is in excellent agreement with other independent experimental and theoretical studies appearing in the literature.