Catalysts Development Of Methanol To Aromatics Reaction

Hierarchical ZSM-5 zeolite has the combination of advantages of zeolites and mesoporous materials, and possesses a good prospect of industrial applications. Hierarchical ZSM-5 was directly synthesized by solvent vaporation routine with organosilane as mesopore directing agent, silica sol as Si source and Al2(SO4)3·18H2O as Al source. Optimal raw materials ratios were n(SiO2)/n(Al2O3)=60, n(Na2O)/nSiO2)=0.075, n(H2O)/n(SiO2)=20, n(PTMS)/n(SiO2)=0.05, (1,6-HMD)/n(SiO2)=0.19, n(TPABr)/n(SiO2)=0.01. Dry gel contained Si and Al source was impregented by the mixed templating agents, followed by hydrothermal crystallization at 165℃ for 72h. The influences of raw material components and crystallization conditions were investigated. The obtained zeolites are characterized by ICP, XRD, SEM, FT-IR, NH3-TPD and N2 adsorption-desorption. HP-ZSM-5exhibited good performance in MTA reaction, the aromatics and BTX yield were 40.5% and 29.3%.Hetero-substitution ZSM-5 which contains Zn was synthesized by the same way. Meanwhile, a method to prepare Zn-containing or Zn-full ZSM-5 zeolites without Na+ was studied. The MTA reaction results over Zn/ZSM-5-IE, Zn-ZSM-5, ZnZSM-5, ZSM-5 and HP-ZSM-5 indicated that different Zn introducing methods caused variation of aromatics selectivity. The sequence of product aromatics selectivity from high to low was Zn/ZSM-5-IE> HP-ZSM-5> ZSM-5> Zn-ZSM-5> ZnZSM-5.The shaping mehod of spherical catalysts for moving bed was also studied. The proper shaping conditions were n(ZSM-5):n(y-Al2O3)=7:3 or 6.5:3.5, c(HNO3)= 15wt.%-20wt.%, water:powder=2.0g/ml, then calcinating at temperature 550℃ for 3h with heating rate of 3℃/min.