초록 |
Coke deposition during methanol conversion tohydrocarbon over HZSM-5 has been studied in a fixed bed reactor at 500oC. The HZSM-5 catalysts withSiO2/Al2O3 ratios of 40 and 280were synthesized and characterized by XRD, SEM, N2-sorption and NH3-TPD.The nature of coke was investigated byN2-sorption, EA and UV-VIS. If the acidity of HZSM-5 is low (SiO2/Al2O3=280), the coke deposited are mainly mono- or bi-aromatics which did not affect the catalyst activity significantly. On the other hand when the acidity is high (SiO2/Al2O3=40), the coke deposited contain polycyclic aromatics with 3 or 4 fused rings which lead to significant deactivation after 24 h. |