Abstract
Herein, a series of SAPO-11 molecular sieves were modified by hydrochloric acid and citric acid.
Highlights
Xiaoxiao Wang, a Zhenmin Liu,a Fang Guo,b Yingchun Wang,a Xianxian Wei,c Peng Li,a Yongbing Xue,a Yuanyang Wang,*a Shaoqing Guo*c and Yue Yud
The physicochemical properties of SAPO-11 molecular sieves and dealuminated SAPO-11 molecular sieves were characterized by inductively coupled plasma-optical (ICP), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), FT-IR, N2 adsorption– desorption, NH3-TPD, Py-IR, and 29Si MAS NMR, and the catalytic performances of these samples were studied for the methylation of naphthalene with methanol
The XRD results showed that the modi cation of SAPO-11 by hydrochloric acid and citric acid decreased the relative crystallinity of the sample without destroying the AEL topology of SAPO-11
Summary
2,6-Dimethylnaphthalene (2,6-DMN) is an important intermediate in the synthesis of polyethylene naphthalene dicarboxylate (PEN). SAPO-11 has shown high catalytic performance in the methylation of naphthalene, several modi cation techniques can further improve the catalytic performance of the SAPO-11 molecular sieve catalyst. Acid dealumination is an important method to improve the catalytic performance of molecular sieves through the modi cation of pore structure and. Hydrochloric acid eliminates the strong and weak acid sites simultaneously without destroying the skeleton structure of the molecular sieve and improving the catalytic performance and stability.[13] Najar et al studied the effect of acid dealumination on the physico-chemical properties of Y molecular sieves and showed that all acids were effective in removing Al from the framework. A series of SAPO-11 molecular sieves were modi ed by citric acid and hydrochloric acid to investigate the in uence of acid-dealumination on the physicochemical and catalytic performances of SAPO-11 for the methylation of naphthalene. The physicochemical properties of SAPO-11 molecular sieves and dealuminated SAPO-11 molecular sieves were characterized by ICP, XRD, SEM, FT-IR, N2 adsorption– desorption, NH3-TPD, Py-IR, and 29Si MAS NMR, and the catalytic performances of these samples were studied for the methylation of naphthalene with methanol
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