碱改性对甲醇芳构化催化剂Zn/La-HZSM-5性能的影响

Alkaline-treated Zn/La-HZSM-5 catalysts for methanol aromatization

采用碱处理对Zn/La-HZSM-5分子筛进行改性,调变分子筛的酸性和择形性能,评价其在甲醇芳构化反应中的性能。采用N_2低温吸附-脱附、NH_3-TPD和XRD等方法表征催化剂。结果表明,碱处理的Zn/La-HZSM-5分子筛催化剂孔体积和比表面积增加,酸量碱处理后降低,Zn改性后增加,催化剂的催化性能显著改善。0.3 mol·L^(-1 )NaOH溶液处理的Zn/La-HZSM-5分子筛催化剂在0.1 Mpa、TOS=10 h、WHSV=0.8 h^(-1)、437℃的反应条件下轻质芳烃收率41.82%,具有较高的芳烃收率和反应稳定性。

Zn/La-HZSM-5 catalysts were modified by alkaline treatment to adjust acidity and shape-selectivity,and tested in methanol aromatization.Physicochemical properties of these catalysts were appropriately characterized by N 2 isothermal adsorption-desorption,NH 3-TPD and XRD.Results showed that the amount of acid sites decreased,pore volume and specific surface area increased by alkaline treatment.After Zn modification,amount of acid sites increased.Therefore,Zn/La-HZSM-5 catalysts had better activity and stability in aromatization reaction.Light aromatics yield of 41.82%was attained under the condition of reaction pressure 0.1 MPa,space velocity 0.8 h-1,reaction temperature 437℃,and reaction time 600 min over Zn/La-HZSM-5 modified by 0.3 mol·L-1 NaOH solution.