A DFT Study On Zr-SBA-15 Zeolite Catalyzed Reaction From Ethanol To 1,3-Butadiene

1,3-butadiene is an important raw material in chemical industry,which is generally used in the production of synthetic polymers and rubbers.1,3-butadiene is mainly obtained as by-product in ethylene production by the extraction technology,which leads to the production and price of 1,3-butadiene dependent on ethylene demand.As with the ethanol production technology is widely applied and developed,the conversion process from ethanol to 1,3-butadiene has attracted extensive attentions in recent years.In this work,the model of modified Zr-SBA-15 zeolite was constructed.Density Functional Theory(DFT)calculations simulation were employed to study the electronic properties and the mechanism of ethanol conversion to 1,3-butadiene on Zr-SBA-15 to clarify the improvement mechanism of Y to Zr-SBA-15 and elucidate the reaction mechanism of 1,3-butadiene synthesis from ethanol.Firstly,using the DFT method,a systematic study of the adsorption of key reaction species involved in the reaction of 1,3-butadiene and the surface properties of Zr-SBA-15 zeolite catalysts was done.The adsorption and co-adsorption of the species involved in the conversion from ethanol to 1,3-butadiene on Zr-SBA-15zeolite were examined systematically to identify the most stable adsorption configurations of relevant species.The Zr atom site and the role of it in adsorption were studied as an active site,.Secondly,in this work,we explored the influence of Zr-SBA-15 molecular sieve catalyst on the reaction process of ethanol to 1,3-butadiene.It was found that dehydrogenation of ethanol toacetaldehyde,aldol condensation and Meerwein–Ponndorf–Verley–Oppenauer(MPVO)reduction of crotonaldehyde with ethanol were considered as the reaction route.It was indicated that the reaction energy barrier of the aldol condensation reaction should be increased,and the activity of the catalyst can be enhanced,which lays the foundation for the study of the influence of the addition of the auxiliary agent on the reaction process.Finally,the influence of Y as rare earth metal promoter on the structure and catalytic properties of Zr-SBA-15 zeolite was explored.The bridge oxygen atom Ob~1in Zr-O-Y specy would play a crucial role in the reaction.In the catalyst,the addition of Y could promote the progress of the aldol condensation as the key step.The addition of Y made the Ob~1 atom of Zr-O-Y specy would exhibit the strongest alkaline and reductive sites on the Zr-SBA-15 zeolite surface.The addition of Y could further increase the activity of Zr-SBA-15 catalyst.