Study On The Catalysts Of Styrene Epoxidation To Styrene Oxide&acetone Condensation To Isophorone

Styrene oxide and isophorone are important fine chemicals in chemical industry,which have been widely used in field of organic synthesis,fragrances and pharmacy.With the increasing market demand in recent years,the synthesis of styrene oxide and isophorone has become a hot research topic in the field of catalysis and organic synthesis.The objective of this work is to achieve high-efficiency catalytic synthesis of styrene oxide and isophorone by synthesizing Mg-based catalysts for acetone condensation and styrene epoxidation.The content of this study is divided into two parts.?1?A series of MgO catalysts were prepared by the calcination of different magnesium precursors for catalytic epoxidation of styrene.The MgO catalyst synthesized from Mg?OH?₂ exhibited a better catalytic performance,the styrene conversion was 98.2%,and the styrene oxide selectivity reached 99.6%.In addition,by examining the effect of calcination temperature,it was found that the MgO catalyst calcined at 700 °C showed an excellent catalytic activity.Secondly,the additives,reaction time,reaction temperature,the amount of catalysts and auxiliaries used,and the molding pressure of the catalyst have been investigated,it was found that the optimal reaction conditions were:the mass ratio of catalyst to styrene was 0.18:1,and the mass ratio of auxiliaries to styrene was 0.25:1,in 60 ? with tbe time of reaction 10 h,under the condition of using H₂O₂ as oxidant and acetonitrile as solvent and auxiliary Na2COs.Finally,the efifects of acetonitrile,H₂O₂ and MgO catalysts on amplification evaluated were investigated.With an acetonitrile/styrene volume ratio of 2.4:1,the styrene conversion and styrene oxide selectivity can reach 99.3%and 93.9%,respectively.The amplification of the catalyst has little effect on its catalytic performance,and the catalyst has an excellent reaction stability under the optimized reaction conditions.?2?The catalytic activity of vapor phase condensation of acetone on the traditional magnesium aluminum solid base catalyst is poor.In this work,Ca,Zr or Cr doped Mg-Al composite oxide catalysts have been prepared by precipitation and hydrothermal method.The as-prepared catalysts were characterized by XRD,BET,CO₂-TPD,etc.,to illuminate structure-activity relationship of the catalysts with different metal doping and different synthesis method.The experimental results show that Zr doping can significant improve the reactivity of the Mg-Al catalyst for acetone condensation.Hydrothermal synthesis of hydrotalcite with a Mg:AI:Zr molar ratio of 39:20:2 was calcined at 500? for 6 h,the obtained Mg-Al-Zr catalyst has an acetone conversion of 32.9%and an isophorone selectivity of 84.6%under the reaction conditions of acetone liquid hourly space velocity 2h-1 hreaction temperature 300 °C and atmospheric pressure.In addition,high reaction pressure of acetone condensation has no obvious effect on the acetone conversion of the catalyst,but it significantly reduces the selectivity of isophorone and increases the heavy by-products.