Abstract:
ZSM-5 zeolites were treated by Na
2CO
3 solutions with different concentrations and characterized by XRD, XRF, SEM, N
2 sorption and NH
3-TPD techniques; the influence of Na
2CO
3 treatment on their pore structure, acidity and performance in thiophene alkylation was investigated. The results showed that the BET surface area, external surface area and mesoporous volume of the ZSM-5 zeolites were enhanced through Na
2CO
3 treatment and the acidity was also modulated without altering the microporous structure of ZSM-5 zeolites. The activity and the selectivity to alkylates of the ZSM-5 zeolites in thiophene alkylation are also improved after Na
2CO
3 treatment. With the increase of Na
2CO
3 solution concentration, the thiophene conversion over the hierarchical ZSM-5 zeolites increases gradually, while the selectivity to alkylates increases first, reaches a maximum and then decreases along with the Na
2CO
3 solution concentration. When the Na
2CO
3 concentrations are 2 and 3 mol/L the thiophene conversions and alhylation selectivities are 81.26%, 73.15% and 90.57%, 72.59%, respectively.