Study On The Synthesis Of Ortho-phenylphenol From Cyclohexanone Dimmers

Ortho-phenylphenol is an important new type of fine chemical product and organic intermediate, widely used in anti-corrosion sterilization, auxiliaries and surfactant, synthesis of new plastic, resin and polymer stabilizers and flame retardants, synthesis of new drugs, and other fields. Manufacturing Ortho-phenylphenol from cyclohexanone has been widely developed because of its cheapness, low pollution and high yield. But up to now, there is only a few domestic manufacturers producing this product. So it is very important for the investigation in the synthesis of Ortho-phenylphenol.In this paper Ortho-phenylphenol was prepared from cyclohexanone dimmers by catalytic dehydrogenation, and the research was focused on the chose of dehydrogenation catalyst and its optimization. The catalyst performance was evaluated with the self-built fixed-bed reactor. This paper studied the catalyst performance of three kinds of modifiers, i.e., K₂SO₄ and KOH, MgO, Mg-Al complex. It's proved that with the modification of K₂SO₄ and KOH the dehydrogenation catalysts had the highest activity, and with the modification of MgO, Mg-Al complex, the dehydrogenation catalysts had the best selectivity and stability. Generally speaking, with the modification of Mg-Al complex, the catalyst had the best performance.The impact of the amount of K₂SO₄ and KOH was studied, and it turned out with the increase of alkali, the activity of the catalyst declined. And through the change of residence time and pre-poisoned with CS₂, the stability of the catalyst was improved. 5 hr after the reaction, OPP selectivity can still maintain 81%. At the same time, by comparing the impact of excessive impregnation with same volume impregnation, it's proved that the catalyst prepared by excessive impregnation had higher dehydrogenation activity. And a reaction net-work was achieved under this catalyst system.The impact of the amount of MgO was also studied. It turned out with w (Mg) = 3.75%, the dehydrogenation catalysts had the best selectivity and stability, and with w (Mg+Al) = 3.22%, w (Mg): w (Al)= 3.2: 1, the same result was got.And in this paper it's also proved that with the modification of Mg-compounds, less by-product biphenyl was formed.