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
In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study th...In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study the effect of Fe content in the MFI on the aromatic selectivity.The CO_(2)to aromatics selectivity over H-[Fe]-ZSM-5/ZnO-ZrO_(2)is maximized at Si/Fe ratio=160.At lower Fe contents,the CO_(2)to aromatics selectivity is affected by limiting the Lewis acid site density.At high Fe loadings,the reduction of Fe sites leads to more production of CO and oxygenates.The reduction during pretreatment and reaction provides reduced Fe2+extraframework ions,with the appearance of these species concomitant with enhanced CO and oxygenate formation during the reaction.展开更多
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supported by the U.S.Department of Energy,Office of Fossil Energy under Award Number DE-FE0031719Christopher W.Jones acknowledges the John F.BrockⅢChair in Chemical and Biomolecular Engineering at Georgia Tech.This work was performed in part at the Georgia Tech Institute for Matter and Systems,a member of the National Nanotechnology Coordinated Infrastructure,which is supported by the National Science Foundation(ECCS-2025462)+1 种基金This research used beamline 7-BM(QAS)of the National Synchrotron Light SourceⅡ(NSLS-Ⅱ)at Brookhaven National Laboratory(Contract No.DESC0012704)supported in part by the Synchrotron Catalysis Consortium(Grant No.DE-SC0012653).
文摘In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study the effect of Fe content in the MFI on the aromatic selectivity.The CO_(2)to aromatics selectivity over H-[Fe]-ZSM-5/ZnO-ZrO_(2)is maximized at Si/Fe ratio=160.At lower Fe contents,the CO_(2)to aromatics selectivity is affected by limiting the Lewis acid site density.At high Fe loadings,the reduction of Fe sites leads to more production of CO and oxygenates.The reduction during pretreatment and reaction provides reduced Fe2+extraframework ions,with the appearance of these species concomitant with enhanced CO and oxygenate formation during the reaction.
