Abstract:
ZSM-5 zeolite with a SiO
2/Al
2O
3 mol ratio of 50 as the raw material was treated either by adding tetrapropylammonium hydroxide solution for secondary crystallization after pre-treating with Na
2CO
3 solution or directly by Na
2CO
3/TPAOH mixed solution, to prepare the micro-mesoporous hierarchical HZSM-5 catalyst;the catalytic performance of resultant micro-mesoporous HZSM-5 in thiophene alkylation was then investigated.The results showed that if the raw ZSM-5 material is first pre-treated with 4 mol/L Na
2CO
3 and then crystallized for the second time in the presence of 0.3 mol/L TPAOH and at 170℃ for about 24 h, the resultant micro-mesoporous HZSM-5(CO
32--TPA
+, 0.3-24-170) has a moderate pore diameter and acidity and exhibits the highest conversion of thiophene (99.1%) in alkylation.However, if the raw ZSM-5 is treated by the mixed solution of Na
2CO
3 and TPAOH, the dissolved SiO
2 may block the pores and channels, leading to lower acidity and smaller pores, which is not suitable for the thiophene alkylation.