Study On The Process Of Gas Phase Synthesis Of 3,5-Xylenol By Acetone

3,5-xylenol is an important chemical raw material and organic intermediate.It has many downstream products and a wide range of applications.It was mainly used to synthesize disinfectants,antioxidants,insecticides,vitamin E,etc.,and plays an important role in the fields of industry,pharmacy and medicine.In recent years,there has been an overcapacity of acetone,and the development of downstream products based on acetone has been increasing.In this paper,acetone was used as raw material to synthesize 3,5-xylenol in a gas phase,and it has based on a two-stage fixed-bed catalyst evaluation device.The process route adopts a combination of homogeneous catalysis and heterogeneous catalysis,which increases yield.In this paper,the reaction product of acetone vapor phase synthesis of 3,5-dimethylphenol was analyzed and identified.The reaction catalyst was screened and modified,and the reaction process was optimized.The mechanism of the reaction process was explored and a reaction network diagram was constructed.The catalyst screening results were as follows:heterogeneous catalyst,5%CaO/?-Al₂O₃ in the upper reaction furnace,15%ZnO/?-Al₂O₃ in the lower reaction furnace,and 4:1 nitromethane and 1-chlorobutane as the homogeneous catalyst.The rare earth metal was modified by the lower stage catalyst,and the modification results showed that the loading of the rare earth metal improved the stability of the catalyst.The deactivation analysis and regeneration investigation of the lower catalyst of easy carbon deposition were carried out.The SEM-EDX,XRD,BET and other characterizations of the combined catalysts show that the catalyst deactivation is mainly due to the catalyst surface area carbon during the reaction.The regeneration activity was examined by calcination,and the regenerated catalyst recovered partial activity at a yield of about 70%of the fresh catalyst.The optimum process conditions:heterogeneous catalyst loading of 20g,homogeneous catalyst addition of 2%wt,in N₂ atmosphere,upper reaction furnace 270?,lower reaction furnace 500?,system pressure 0.5 MPa,feeding speed 0.8 mL/min.The acetone conversion rate was 85.23%,the target product selectivity was 51.34%,and the by-product mesitylene selectivity was 17.34%.