Study On Synthesis And Purification Of O-phenylphenol

O-phenylphenol is widely used as fine chemical product in antisepsis, flame retardant, auxiliary agent for printing and dyeing, surfactant and so on. The international demand is great, but the production technology is monopolized by several foreign corporations. Now, the main process in industrial production is condensation of cyclohexanone followed by dehydrogenation.The dimer of cyclohexanone was continuously synthesized by liquid-solid catalytic reactive distillation with cyclohexanone as raw material and aluminum contained material as catalyst in this paper, the yield of the dimer of cyclohexanone reached 97-98%. Then the kinetics of condensation of cyclohexanone was studied, the Adsorption-based Model and the Pseudohomogeneous Model were used to describe the reaction respectively, it was found that the former is more accurate but with too many parameters, while the expression of the latter is much simpler and could be used for industrial design with a reasonable error range.Next in this paper, the dimer of cyclohexanone was used as raw material to synthesize o-phenylphenol by dehydrogenation, and the catalyst for dehydrogenation was studied. The yield of o-phenylphenol reached 83% by liquid-solid catalytic dehydrogenation method when Pt-Na₂CO₃/C catalyst was used without any hydrogen acceptor. Then gas-solid catalytic dehydrogenation method was researched. The optimized 1%Pt-5%water insoluble metal compound/C catalyst can be used steadily for about 340 hours, the total input of the dimer was about 21.8kg/gPt and the production of o-phenylphenol was about 19.6kg/gPt, moreover, the recycle of Pt is easy, so it is considered to have prospect towards industrialization. Finally characterizations and analyses of the catalyst for dehydrogenation were conducted, the results explained the phenomena in experiments well and gave directions toward further optimizations of the catalyst.Purification of o-phenylphenol was studied at last in this paper by combining alkali treatment with two-stage counter-current extraction. The main factors influenced the yield of o-phenylphenol were got by theoretical derivations and were optimized. The optimized parameters are: the mole ratio of NaOH to o-phenylphenol is 1.01, the volume ratio of extractant to NaOH solution is about 0.35 and the concentration of NaOH solution is about 11%. When the content of 2-cyclohexylphenol in raw dehydrogenated product is below 1%, o-phenylphenol can be purified to 99.5% with a yield of 97.4% under optimized purification process.