| 摘要： |
BACKGROUND: In the post-oil society, the methanol-to-olefin (MTO) conversion is a successful non-oil route for the production of ethene, propene and butene, which are important chemicals in modern chemical industry. Recently, the global demand for propene increased, which makes high propene selectivity attractive in the MTO conversion. However, looking for an effective catalyst is the main challenge. RESULTS: H-MCM-22 zeolite was dealuminated with nitric acid, oxalic acid and ammonium hexafluorosilicate (AHFS). Then, the parent and dealumianted samples were examined in the MTO reaction. The results showed that the total acid amounts decreased and the distribution of Bronsted acid sites in the pores of H-MCM-22 were reregulated after the different dealumination procedures. The results of thermogravimetric (TG) analysis of the spent samples demonstrated that H-MCM-22 (10A) dealumination with 10 mmol L-1 AHFS solution had the lowest coking rate and coke selectivity, which makes it exhibit the longest lifetime (54 h), and highest propene and butene selectivity (71.8%). CONCLUSION: Dealumination with AHFS is an effective method for H-MCM-22. Because it can eliminate almost all the extra-framework aluminum (Al-EF) species and concentrate the Bronsted acid sites in the sinusoidal channels which promote the propene and butene formation with a resistance to carbonaceous deposition in the MTO reaction. (C) 2016 Society of Chemical Industry |
