Study On The Preparation Of O-phenylphenol

O-phenylphenol is mainly used in manufacture of an anti-microbial for treatment of citrus fruits, carrier of disperse dyes and thermally stable and incombustible fibers. Recently, the demand of o-phenylphenol increased drastically. Manufacturing o-phenylphenol from cyclohexanone has been widely used because of its cheapness, low pollution and high yield. But up to now, there is few domestic manufacturers producing this product. So it is very reasonably important of the investigation in the synthesis of o-phenylphenol.Cyclohexanone dimer, including 2-(1-cyclohexenyl)cyclohexanone and 2-cyclohexylidene-cyclohexanone, were prepared in the self-condensation reaction from cyclohexanone in which sulfuric acid was used as the catalyst. The reacted mixture was then washed by water, neutralized by alkali and rectified so as that pure cyclohexanone dimer were received which was the stuff of the dehydrogenation in the following step. The cyclohexanone dimer were dehydrogenated by Pt-KOH-K₂SO₄/γ -Al₂O₃ and o-phenylphenol was obtained at the end.In the study on the self-condensation of cyclohexanone, the effects of the reaction temperature and the concentration of sulfuric acid were investigated. According to the self-condensation mechanism, the kinetic equation was developed. And kinetic parameters of Arrhenius equations of the reactions were obtained through fitting by computer based on the experimental data. It was found that the forward and reverse activation energy that form cyclohexanone dimer are E_a1=74.99kJ·mol^-1 and E_a2=73.12kJ·mol^-1, respectively. The forward and reverse activation energy that form cyclohexanone trimer are E_a3=92.26kJ·mol^-1 and E_a4=56.71kJ·mor^-1, respectively. The corresponding pre-exponential factor are k₀₁=1.97×10⁸L²Â·mol^-2·min^-1, k₀₂=1.33× 10⁸V·mol^-2·min^-1, k₀₃=5.57× 10⁸L²Â·mol^-2·mm^-1 and k₀₄=5.08×10⁹L²Â·mol^-2·min^-1. From the results it can be conclude that the reactions that form cyclohexanone dimer and cyclohexanone trimer are more easily carried out in high temperature. So reaction in high temperature is good for forming cyclohexanone dimer and reaction in low temperature is good for restraining the forming of cyclohexanone trimerThe preparation art of dehydrogenation catalyst Pt-KOH-K₂SO₄/γ -Al₂O₃ was optimized in this paper. When the impregnation time is 2 hour, the load of activator is 0.6%, the ratio between K₂SO₄ and KOH is 3.0, the roasting time is 1 hour and theconcentration of HC1 in the impregnating solution is 0.3mol/L, the catalytic activity and selectivity for O-phenylphenol is the best.In the experiment, the residence time was changed to develop the main dehydrogenation reaction mechanism. The side reaction network was also discussed from pumping the pure main byproduct of the dehydrogenation reaction into the catalyst bed. So the whole reaction network was given at last, which could serve as a guidance in the optimizing of the preparation of dehydrogenation catalyst and be very important for the study of reaction kinetics and the magnifying of reactor.