Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-I-14Relations ‘rate vs alcohol content’ for n-butyl (1) and i-butyl (2) alcohols are analogous toone for isoamyl alcohol (Fig. 4, t = 60°C). It is caused by higher water solubility of butanolsin comparison with isoamyl alcohol.r 0·10 3 , mol/(l·min)40 Fig. 330232010 1r 0·10 3 , mol/(l·min)0,020Fig. 40,0150,0100,005120 1 2 3 4 5C al,0, mol/l0,0 0,5 1,0 1,5 2,0 2,5 3,0C al,0, mol/lThe analysis of finding has resulted in kinetic equation including rate of alcohol oxidationR cat,aq on the aqueous phase wetted catalyst surface and rate of non-catalytic oxidation in thevolume of the organic phase R ncat,org :R = R cat,aq + R ncat,orgIt has been established that the catalyst during reaction loses activity owing to reversibleover-oxidation. Reaction rate decreasing in the range 2 in a Fig. 3 is caused by formation ofan organic phase and snowballing of a fraction of the organic wetted surface of the catalyst.The contribution of catalytic reaction to oxidation rate is determined by catalyst contentC cat , organic wetting degree of catalyst surface β, alcohol (θ al ) and oxygen (θ Ox ) surfaceconcentrations, and also by catalyst over-oxidation degree X Ov :R cat,aq = k cat,aq (1–X Ov )C cat (1–β)θ al θ OxThe non-catalytic reaction contribution is determined by a volume fraction of an alcoholorganic phase α and an oxygen partial pressure p Ox :R ncat,org = k ncat,org αp OxIt has been displayed that over-oxidation and reactivation of the catalyst occur on theaqueous phase wetted surface. The catalyst over-oxidation key factor is the oxygen surfaceconcentration, and rate of a reactivation is determined by the reduction properties of anaqueous phase, including alkali concentration.238