Study On CoLa/Al₂O₃ Catalysts For The Dehydroamination Of Ethanol To Acetonitrile

As an important organic intermediate,acetonitrile（ACN）is widely used in pharmaceutical,agrochemical,petrochemical,and polymer industries.However,with the increasing demand for its downstream products,the current ACN production route seems to be unable to meet the industrial demand at this stage,because commercial ACN is usually produced as a by-product of propylene ammonia oxidation with low yield and the reaction process has highly toxic by-product HCN generation,therefore,it is crucial to develop a higher yield and cleaner and more environmentally friendly ACN production route.The ethanol dehydroamination to acetonitrile route used in this paper is relatively clean,economical and safe.And the ethanol conversion and acetonitrile selectivity are relatively high.Meanwhile,the world’s first industrial demonstration plant for coal-based ethanol has been put into operation in China,which provides abundant ethanol feedstock for ethanol dehydrogenation to acetonitrile,therefore,this paper focuses on the exploration of ideal catalysts for the reaction of ethanol dehydrogenation to acetonitrile and to obtain optimal reaction conditions guided by thermodynamic calculations.And the reaction performance of Co/Al₂O₃ catalysts modified with different levels of La in the reaction of ethanol dehydrogenation and ammonification to acetonitrile was evaluated in a fixed-bed reactor.The catalysts were characterized by XRD,XPS,TEM,TG-DTA,IGA,NH₃-TPD,and N₂ adsorption-desorption.The results showed that the catalytic performance of the20Co/Al₂O₃ catalysts doped with rare earth elements（La,Ce,Pr）was significantly improved in the reaction of ethanol dehydroamination to acetonitrile,and the dispersion of surface cobalt species in the 20Co/Al₂O₃ catalysts with suitable content of La addition was good and the Coparticles were smaller,while the catalysts possessed a larger specific surface area,Stronger adsorption capacity and faster diffusion of ACN of the modified catalysts are faster,and they have better anti-carbon performance in the long time reaction.Meanwhile,the La-doped catalyst was preferred to synthesize ACN from imine rather than ethylamine（EA）in the synthetic route,and from the thermodynamic calculations,the selectivity of each product changes according to the reaction conditions,Meanwhile,the effect of reaction conditions at different temperatures,alcohol-to-ammonia ratios,air velocities and pressures on the reaction of ethanol dehydrogenation to acetonitrile was investigated and the optimal reaction conditions were derived,and the reaction lifetime of the 0.25La-20Co/Al₂O₃catalyst was examined.The catalyst was able to maintain more than 99%ethanol conversion and 92%acetonitrile selectivity with no acetylamine formation even after a long reaction time of 360 h.It can be seen that the 20Co/Al₂O₃catalyst modified with suitable rare earth elements has good catalytic activity and stability,and has a promising application in industrial production.