O-phenyl phenol preparation catalyst by cyclohexanone dimer dehydrogenation and preparation method thereof

Abstract

The invention discloses an o-phenylphenol catalyst prepared by dehydrogenating cyclohexanone dimer, and a preparation method thereof. A carrier of the catalyst is alumina modified with rare earth oxide, and the catalyst consists of alkali oxide and precious metal which are loaded on the carrier. The invention has the most remarkable characteristic of using the alumina modified with rare earth oxide as the carrier, and another remarkable characteristic of the invention is the preparation method of the catalyst, and the method adopts an isopyknic fractional-step impregnation process, avoids competitive adsorption among components, increases the bonding strength between the components and the carrier, and the like. The catalyst has the advantages of high selectivity to o-phenylphenol, few byproducts, simple preparation process, good stability and capability of simple activation and regeneration after coking deactivation, and is an excellent high-selectivity catalyst with industrial practical value.

Description

technical field [0001] The invention relates to a catalyst for preparing ortho-phenylphenol by dehydrogenation of cyclohexanone dimer and a preparation method thereof. Specifically, the carrier of the catalyst is aluminum oxide modified by rare earth oxide lanthanum oxide (La 2 o 3 / Y-Al 2 o 3 ), alkali metal oxide potassium oxide (K 2 O) and the noble metal platinum (Pt). The performance of the catalyst prepared by this method is obviously better than that of the co-impregnation method. Finally, hydrogen diluted with nitrogen is used to reduce and activate the catalyst in a fixed-bed reactor, and the regenerated catalyst can be reused after deactivation by carbon deposition. Background technique [0002] Ortho-phenylphenol (OPP for short) is an important and widely used fine organic chemical product. It can be used as a dye intermediate, a heat stabilizer for plastics and a flame retardant for polymers. It can also be used for the fluorescence determination of trisac...

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Problems solved by technology

This catalyst has poor stability, low conversion rate and selectivity, and many reaction by-products

[0009] Chinese patent CN200610097298 discloses a preparation method of Cu-Mg catalyst for the preparation of o-phenylphenol. Co-precipitation method is adopted, and the conversion rate and selectivity are also high, but the stability is not good and the service life is not long

[0010] Chinese patent CN200710022479 discloses a preparation process of ortho-phenylphenol. The dehydrogenation reaction is carried out in a fixed-bed reactor, and the obtained product is then subjected to vacuum distillation and cooling slices to obtain the ortho-phenylphenol product. The focus of the article is on ortho-phenylphenol Although it is mentioned that the catalyst components are rare earth elements, alkali metals and noble metals, it fails to clearly mention the components loaded on the catalyst carrier and the preparation method of the catalyst.

[0011] Chinese patent CN200710103661 discloses a method for synthesizing o-phenylphenol with aniline compounds. Aniline compounds are diazotized and coupled to generate biphenyl compounds, and then hydrolyzed to obtain o-phenylphenol, but the yield is very low and the lifespan is very short. Short, and there are many risk factors in the drying process of diazonium salt, which is not conducive to popularization and application

In the initial stage of the reaction, the dehydrogenation product o-cyclohexylcyclohexanone is generated. As the reaction time increases, o-cyclohexylphenol and OPP gradually increase, but OPP will continue to cyclize to form dibenzofuran, and the selectivity of OPP is not good. high

[0018] Although the above-mentioned patented technologies and documents have their own characteristics, they also have their own shortcomings. The outstanding problems are that the selectivity of o-phenylphenol is low, the process is not conducive to industrial production, the catalyst has poor stability, many reaction by-products, and the surface of the catalyst is easily Coking, catalyst life is not long, catalyst cost is high, and individual dehydrogenation products need to undergo alkali dissolution and pickling treatment to obtain qualified products, etc.

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