Catalyst And Technology For The Synthesis Of O-Phenylphenol

O-phenylphenol (OPP) was an important organic chemical which was widely used in many fields. Nowadays OPP was mostly catalytically synthesized through a two-step process, that was, cyclohexanon's self-condensation and dimers'dehydrogenation. In this thesis, catalysts applied to the two-step reactions had been studied. A seiries of solid catalysts with high conversion and excellent selectivity for the self-condensation reaction of cyclohexanone, and dehydrogenation catalysts with high dimer conversion rate and OPP selectivity as well as the ideal stability had also been developed.Results indicated that as to the self-condensation reaction of cyclohexanone, conventional H2SO4 catalyst had relatively higher conversion rate but it showed lower selectivity and could not be recovered and regenerated, whileγ-Al2O3 catalyst had ideal catalytic activity and much higher selectivity than the former and could be regenerated for over eight times. Mechanism study ofγ-Al2O3-catalyzed condensation reaction indicated that its catalytic performance was not so necessarily connected with its pore properties and crystalling phase but had close relations to its surface Lewis acidity. In-situ IR analysis was firstly adopted in this paper to study the condensation reaction of cyclohexanone on the surface ofγ-Al2O3 catalyst and results confirmed that cyclohexanone indeed could be condensated under catalysis effect ofγ-Al2O3 and IR results from different species'adsorption behaviors on Al2O3 surface also reflected that cyclohexanone's self-condensationi reaction most likely underwent under catalysis effect with the Lewis acid sites on the surface ofγ-Al2O3 material.Results from the research of the dehyogenation catalysts showed that Pt/Al2O3 was the best mono-component catalyst and bi-component catalysts such as Pt-Pd, Pt-Sn and Pt-Re showed poor dehydrogenation activities.γ-Al2O3 was the ideal support which showed relatively the best performance as well as the stability. Additve-modification research works indicated that K additives had better modification effect than other modifiers and K2CO3 was the best among them. Results reflected that K additives had modification effect at two aspects, that were, firstly the electrical promotion effect as to the Pt component and secondly the suppressing of the surface acidity onγ-Al2O3 support, and the former was relatively the more important that the latter. However, stability tests indicated that K-modified catalysts were relatively easier gotten deactivated and mechanism study reflected that carbon deposition was not the main reason for the deactivation and the most probable reason was the migration of K species on the surface of catalyst which led to the excessive loss of Pt active surface by their covering effect. Support-modification studies were focused on in this paper and Li2O, SrO and BaO were found to be prospective modifiers and CeO2 was surprisingly found to have positive effect on the stability of the modified dehydrogenation catalysts. Catalysts with calcined in-situly generated MgAl hydrotalcites as supports also showed good OPP selectivity as well as prospective stability. On the basis of CeO2-modification, combined modification processes such as K-Ce and basic metal oxides-Ce modification methods were adopted to promote catalysts'hydrogenation activity, and more importantly, their stabilities. Several optimistic results had been earned and SrO-CeO2 combined modification catalyst showed the best stability. Life test indicated that 0.5%Pt/5%SrO-5%CeO2-Al2O3 catalyst had excellent performance during a 300h run, whose conversion rate and selectivity could be maintained over 95% and 91% respectively thus made it very promising for industrial use.