A series of as-synthesized HZSM-5 zeolites with different Si/Al ratios(25,90,120,240 and 400)were post-treated by ultrasonication for an optimum time of 60 min.The morphology,acidity and textural properties of HZSM-5 ...A series of as-synthesized HZSM-5 zeolites with different Si/Al ratios(25,90,120,240 and 400)were post-treated by ultrasonication for an optimum time of 60 min.The morphology,acidity and textural properties of HZSM-5 were characterized with XRD,SEM,N_2 adsorption and NH3-TPD techniques.The catalytic performance was evaluated by dehydration of methanol to dimethyl ether(DME),which is a promising gaseous automotive fuel in future.It was found that the Si/Al ratio of HZSM-5 had considerable impacts on its catalytic performance for dehydration of methanol to DME.Its activity increased with decreasing Si/Al ratio from 400 to 25.Ultrasonication of HZSM-5 could significantly improve its catalytic performance.展开更多
In situ catalytic conversion of biomass fast pyrolysis vapors was carried out on HZSM-5 with varying Si/Al ratios(ranging from 20 to 300) at 450 °C. The effects of Si/Al ratios of HZSM-5 zeolites on the distribut...In situ catalytic conversion of biomass fast pyrolysis vapors was carried out on HZSM-5 with varying Si/Al ratios(ranging from 20 to 300) at 450 °C. The effects of Si/Al ratios of HZSM-5 zeolites on the distribution of biomass fast pyrolysis products and carbon deposits on catalysts were investigated. It was quite remarkable that after in situ catalytic conversion the amount of light phenols and hydrocarbons increased significantly while that of heavy phenols decreased a lot. Besides, the yield of cyclopentenones with relatively low oxygen content generally increased. It also indicated that as the Si/Al ratios of HZSM-5 increased, the amount of hydrocarbons and light phenols was found to drop greatly. The amount of carbon deposits was found to be around 8.5% with the exception of HZSM-5 with the Si/Al ratio of 300,which is much lower. Moreover, the carbon deposits yield dropped gradually with increasing Si/Al ratios of HZSM-5.Calcination of spent catalysts at 600 °C helped to restore the catalytic activity to a large extent despite a relatively lower efficiency of deoxygenation. Results indicated that HZSM-5 with relatively high acidity displayed great catalytic performance.展开更多
文摘A series of as-synthesized HZSM-5 zeolites with different Si/Al ratios(25,90,120,240 and 400)were post-treated by ultrasonication for an optimum time of 60 min.The morphology,acidity and textural properties of HZSM-5 were characterized with XRD,SEM,N_2 adsorption and NH3-TPD techniques.The catalytic performance was evaluated by dehydration of methanol to dimethyl ether(DME),which is a promising gaseous automotive fuel in future.It was found that the Si/Al ratio of HZSM-5 had considerable impacts on its catalytic performance for dehydration of methanol to DME.Its activity increased with decreasing Si/Al ratio from 400 to 25.Ultrasonication of HZSM-5 could significantly improve its catalytic performance.
基金supported by the National Basic Research Program of China(2013CB228104)
文摘In situ catalytic conversion of biomass fast pyrolysis vapors was carried out on HZSM-5 with varying Si/Al ratios(ranging from 20 to 300) at 450 °C. The effects of Si/Al ratios of HZSM-5 zeolites on the distribution of biomass fast pyrolysis products and carbon deposits on catalysts were investigated. It was quite remarkable that after in situ catalytic conversion the amount of light phenols and hydrocarbons increased significantly while that of heavy phenols decreased a lot. Besides, the yield of cyclopentenones with relatively low oxygen content generally increased. It also indicated that as the Si/Al ratios of HZSM-5 increased, the amount of hydrocarbons and light phenols was found to drop greatly. The amount of carbon deposits was found to be around 8.5% with the exception of HZSM-5 with the Si/Al ratio of 300,which is much lower. Moreover, the carbon deposits yield dropped gradually with increasing Si/Al ratios of HZSM-5.Calcination of spent catalysts at 600 °C helped to restore the catalytic activity to a large extent despite a relatively lower efficiency of deoxygenation. Results indicated that HZSM-5 with relatively high acidity displayed great catalytic performance.
