A study on catalytic dehydration of 4-hydroxy-3-hexanone （HH） to 4-hexen-3-one （HO） was carried out through conversion of HH over HZSM-5 zeolite catalyst in a fixed-bed reactor （FBR） operating under almospheric ...A study on catalytic dehydration of 4-hydroxy-3-hexanone （HH） to 4-hexen-3-one （HO） was carried out through conversion of HH over HZSM-5 zeolite catalyst in a fixed-bed reactor （FBR） operating under almospheric pressure. The test indicated a relatively high activity of the HZSM-5 zeolite capable of achieving a HH conversion of 99.2% and a HO yield of 83.5%. Catalyst deactivation could be prevented by increasing the reaction temperature by 10 ＂C for every 20 h and adding 2.0% of piperidine in the feed. A catalyst stability test （for 100 h） in FBR showed that the catalyst was active even after 100 h of time-on-stream with HH conversion remaining at 99.2% and HO yield still reaching over 83.5%. Regenera- tion experiment showed that the regenerated catalyst demonstrated a catalytic performance comparable to the fresh one.展开更多
This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging...This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging temperature were decisive factors to control the particle size of Fe-MFI in the range of 50 nm to 600 nm. The introduction of Fe3＋ ions into the zeolitic framework was confirmed by UV （ultraviolet）-visible spectroscopy. In addition, it was observed that the strength of acid site in prepared Fe-MFI was weaker than that of commercial ZSM-5. With decrease in the particle size, the amount of deposited coke decreased so that the catalyst life for the DTO reaction was well promoted. The present catalysts showed the higher light-olefin selectivity （C2= ＋ C3= ＋ C4=） than commercial ZSM-5 catalysts mainly due to the suppression of the formation of paraffins; however, the Fe-MFI catalysts were deactivated rapidly because of their low activity for the cracking of alkenes.展开更多
Biomass is a nature renewable resource which can be used for the production of high value chemicals and bio-fuels. In the present work, the transformation of sawdust into aromat- ics such as benzene, toluene and xylen...Biomass is a nature renewable resource which can be used for the production of high value chemicals and bio-fuels. In the present work, the transformation of sawdust into aromat- ics such as benzene, toluene and xylenes was investigated over a series of zeolite catalysts （NaZSM-5, HZSM-5, ReY and HY catalysts）. Among the tested catalysts, the HZSM-5 catalyst shows the highest activity for the production of aromatics. The yield and carbon selectivity of aromatics reached about 26.5% and 62.5C-mo1%, respectively over the HZSM-5 catalyst under the optimal condition of T=450 ℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2. The effects of the reaction conditions including temperature, gas flow rate, and catalyst/sawdust ratio on the production of aromatics were investigated in detail and the formation of aromatics from lignocellulosic biomass was also addressed.展开更多
基金supported by the Science and Technology Planning Program of Tianjin(Project No.12ZXCXGX21900)
文摘A study on catalytic dehydration of 4-hydroxy-3-hexanone （HH） to 4-hexen-3-one （HO） was carried out through conversion of HH over HZSM-5 zeolite catalyst in a fixed-bed reactor （FBR） operating under almospheric pressure. The test indicated a relatively high activity of the HZSM-5 zeolite capable of achieving a HH conversion of 99.2% and a HO yield of 83.5%. Catalyst deactivation could be prevented by increasing the reaction temperature by 10 ＂C for every 20 h and adding 2.0% of piperidine in the feed. A catalyst stability test （for 100 h） in FBR showed that the catalyst was active even after 100 h of time-on-stream with HH conversion remaining at 99.2% and HO yield still reaching over 83.5%. Regenera- tion experiment showed that the regenerated catalyst demonstrated a catalytic performance comparable to the fresh one.
文摘This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging temperature were decisive factors to control the particle size of Fe-MFI in the range of 50 nm to 600 nm. The introduction of Fe3＋ ions into the zeolitic framework was confirmed by UV （ultraviolet）-visible spectroscopy. In addition, it was observed that the strength of acid site in prepared Fe-MFI was weaker than that of commercial ZSM-5. With decrease in the particle size, the amount of deposited coke decreased so that the catalyst life for the DTO reaction was well promoted. The present catalysts showed the higher light-olefin selectivity （C2= ＋ C3= ＋ C4=） than commercial ZSM-5 catalysts mainly due to the suppression of the formation of paraffins; however, the Fe-MFI catalysts were deactivated rapidly because of their low activity for the cracking of alkenes.
基金ACKNOWLEDGMENTS This work was supported by the National Nat- ural Science Foundation of China （No.51161140331） and the National Key Basic Program of China （No.2013CB228105）.
文摘Biomass is a nature renewable resource which can be used for the production of high value chemicals and bio-fuels. In the present work, the transformation of sawdust into aromat- ics such as benzene, toluene and xylenes was investigated over a series of zeolite catalysts （NaZSM-5, HZSM-5, ReY and HY catalysts）. Among the tested catalysts, the HZSM-5 catalyst shows the highest activity for the production of aromatics. The yield and carbon selectivity of aromatics reached about 26.5% and 62.5C-mo1%, respectively over the HZSM-5 catalyst under the optimal condition of T=450 ℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2. The effects of the reaction conditions including temperature, gas flow rate, and catalyst/sawdust ratio on the production of aromatics were investigated in detail and the formation of aromatics from lignocellulosic biomass was also addressed.
