Effects of Na and K ions on the crystallization of low-silica X zeolite and its catalytic performance for alkylation of toluene with methanol

Journal of the Brazilian Chemical Society

Chinese Academy of Sciences, Taiyuan, China¹  Zhang, Kan¹  Hui, Haitao¹  Wang, Gencun¹  Gao, Junhua¹  University of Chinese Academy of Sciences, Beijing, China¹  Liu, Ping¹ 

关键词: LSX;    synthesis;    Na;    K;    Alkylation;   

DOI  :  10.5935/0103-5053.20130269

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

The crystallization of low-silica X zeolite (LSX) was studied in Na-K gel systems with different extents of replacement of Na by K while fixed content of other components. X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, scanning electron microscopy, infrared spectra, and nuclear magnetic resonance were used to characterize liquid and solid phase. In the synthesis of LSX, the molar ratio of K/(Na+K) affects the crystallization and the composition of final products. A higher mole fraction of K corresponded to a lower crystallization rate, higher concentration of Si in the liquid phase, and lower Si/Al ratio of the obtained LSX. The average size of LSX products steadily increased with the progressive replacement of Na by K in the initial gels, and crystal morphology of the LSX products gradually changed from round to octahedral. For alkylation of toluene with methanol over obtained LSX, the selectivity of ring alkylation product xylene decreased while the side chain alkylation products styrene and ethylbenzene increased with the increased x values except x = 0, which was due to its low crystallinity.

【 授权许可】

Unknown