Study On Green Synthesis Of Adipic Acid By One-step Oxidation Of Cyclohexane

Adipic acid is one of the chemical raw materials with the largest industrial consumption at present.It is widely used in plastics,medicine,nylon and other industries due to its bifunctional group properties characteristic of reacting with a variety of compounds to form high polymers.In industry,adipic acid is mainly prepared by cyclohexane oxidation in the presence of nitric acid by two-step oxidation process with high energy consumption,serious pollution.So process with green and high efficient synthesis of adipic acid has become a hot research topic.In this paper,three series of catalysts were prepared by incipient-wetness impregnation method impregnation method,namely Pt/SiO₂,Fe/SiO₂ and Pt-Fe/SiO₂ catalysts,and the specific surface,pore size distribution and content of Pt and Fe in the catalysts were characterized using AUTOSORB-1,ICP-OES,and XRF respectively.The crystal phase structure of the catalyst was analyzed by XRD.The morphology of crystal particles analyzed by high-resolution SEM.When the catalyst is used in the synthesis of adipic acid,the best catalytic performance and the highest adipic acid yield obtained over the bimetal-supported catalyst..In order to evaluate the regeneration stability performance of Pt-Fe/SiO₂,four regeneration studies were conducted in this experiment.The catalyst activity did not decrease significantly and the catalyst structure was stable.In this paper,more suitable CuO loading was selected and then prepared a heterogeneous and high efficient catalyst suitable for one-step oxidation of cyclohexane to adipic acid through the investigation of pore structure,specific surface area,acidity,morphology characteristics,hydrothermal stability and regeneration performance of series of ITQ-2 molecular sieve catalysts with different CuO loading.The results showed that the yield of adipic acid on CuO/ITQ-2 was up to 18%.In addition,the catalytic efficiency was further improved by optimizing the process parameters of the reaction,including reaction temperature,catalyst dosage,reaction time,system acidity and pressure,which laid a foundation for the further development of a more suitable green catalytic synthesis and reaction system.