摘要
The effects of the synthetic condition of SAPO-11 molecular sieves on ethanol dehydration to ethylene were studied.Product-compositions,ethanol conversion,and selectivity to ethylene of synthesized and commercial SAPO-11 molecular sieves were compared.Results are as follows:the optimal synthetic conditions for SAPO-11 molecular sieves are adding pseudoboehmite before orthophoshporic,using di-npropylamine as the template,having a mass fraction of 40%colloidal silica as the silica source and the starting gel obtained,and running at 200℃ for 48 h.From the patterns of NH3-TPD,the amount of acid synthesized by SAPO-11 molecular sieves is less than that by commercial SAPO-11 molecular sieves,and has a stronger weak acid.Also,ethanol conversion and selectivity to ethylene reached 99%at 280℃ on synthesized SAPO-11,lower by 20℃ compared to commercial SAPO-11.For two SAPO-11 molecular sieves,the by-products in the gas phase are mainly ethane,propane,propene,isobutane,n-butane,propadiene,butylene and some higher hydrocarbons.The by-products in the liquid phase are ethyl ether and acetaldehyde.
基金
This work was financially supported by the National High Technology Research and Development Program of China(No.2006AA020101).
