The Preparation Of Phenylacetaldehyde By Catalytic Rearrangement Of Styrene Oxide In Liquid-phase

Phenylacetaldehyde is an important organic intermediate, which is widely usedin the production of industrial fine chemicals, such as fragrances, drugs, pesticides,etc. The main production process of phenylacetaldehyde is the rearrangement ofstyrene oxide in fixed bed reactor, in which the product is easy to form carbondeposits, leading to catalyst deactivation. Therefore, the rearrangement of styreneoxide in liquid-phase is investigated in this paper.Seven solvents with variant polarity were chosen and the solvent effect on therearrangement was investigated over HZSM-5zeolites with different Si/Al ratios.Moreover, the reaction temperature, the reaction time, the amount of catalyst andsolvent were chosen to be the influencing factors with the yield of phenylacetaldehydeas response. To explore the optimum condition for the rearrangement reaction, thefractional factorial design experiment was adopted.The experimental results showed that DMF, which possesses the strongestpolarity, easily adsorbed on the surface of zeolites, resulting in quick deactivation ofthe catalyst. Other solvents with weaker polarity can improve the reaction rateeffectively, while they can also generate by-products by reacting withphenylacetaldehyde. The weakest polarity or nonpolar solvents were more stable tosuppress the formation of carbon deposits and improved the reaction rate at a certaintemperature. Among all the solvents,1,2-dichloroethane was proven to be the mostsuitable one for liquid-phase rearrangement of styrene oxide. The catalytic activity ofHZSM-5zeolites with Si/Al of25,38,50and80was further explored in the1,2-dichloroethane. The HZSM-5(Si/Al=25), with the strongest acidity, showed thehighest initial catalytic activity, but meanwhile the condensation reactions werepromoted by the excess acid sites which was responsible for the decrease of selectivity.Conversely, the HZSM-5(Si/Al=80), with the weakest acidity, showed an excellentcatalytic performance, over which the yield of phenylacetaldehyde can reach morethan90%. The optimal reaction conditions obtained by fractional factorial designexperiment indicated that the yield of phenylacetaldehyde could reach the highest96.3%when the factors were80°C,1h,3g and40mL, respectively.