Dong Xuesong
Fe-zeolite: Influence of precursors and preparation method
• Anunziata et al. [1]: i-C4H10-SCR on Fe/ZSM-11 catalyst.
• NH4-ZSM-11; Wetness impregnation; Precursors FeSO4
(Samples: A, B. Fe content: 1 and 3 wt%) and Fe(NO3)3
(Sample:C 3 wt%).
Fe-zeolite: Influence of precursors and preparation method
Table 1 Summary of catalyst characteristics
[1] O.A. Anunziata. Applied Catalysis A:General 264 (2004) 93–101.
Fe-zeolite: Influence of precursors and preparation method
Fig.1 Catalytic activity of Fe-zeolites for NOx SCR using samplesA, B and C
• XRD result indicated only in the sample C: hematite phase (ɑ-Fe2O3)
Fe-zeolite: Influence of precursors and preparation method
Fig.2 Experimental results from FTIR spectra of pyridine-Lewis sites(Fen+-Z) for samples A, B and C desorbed at 400 ◦C and 10−4 Torr.
• They concluded: The NOx conversion appears as a function of
the presence of Fe2+ while Fe3+ is less active for the SCR of
NOx with i-C4H10.
• However, the oxidation state difference rather than the anion
may lead to the difference.
• Few paper investigates the precursors effect on Fe-zeolites
SCR.
Fe-zeolite: Influence of precursors and preparation method
• Mhamdi et al. [2]: ethylene ammoxidation
• H-ZSM-5; Solid-State ion exchange; Co precursors (acetate,
chloride, nitrate or formate); nominal Co/Al=1
• Activity: Ac is best in activity and selectivity.
• Chloride, nitrate or formate: Co oxide and isolated Co2+
cationic ion exchange position. while Ac leads to most
isolated Co2+
• However, Kawi et al. [3] observed no difference between
Co(NO3)2 and Co(acac)2 for HC-SCR.
Fe-zeolite: Influence of precursors and preparation method
[2] M. Mhamdi . Applied Catalysis A: General 357 (2009) 42–50
[3] S. Kawi. Applied Catalysis B: Environmental 50 (2004) 37–47
• The role of chlorine
• Ávila et al. [4]: NOx reduction by CH4 on Pd/Al2O3
• Chloride, nitrate or acetate; Impregnation
• PdCl2: much better acitivity especially at high temperature.
• Cl- migrate to the active Pd2+ centres.
• Sobczak et al. [5] found chlorine electron transfer to oxygen
and promotes NO oxidation on Au/MCM-41 for HC-SCR.
Fe-zeolite: Influence of precursors and preparation method
[4] P. Ávila.Chemical Engineering Journal 150 (2009) 8–14
[5] Sobczak. Journal of Catalysis 245 (2007) 259–266
• 陈银飞等 [6] , Fe/β催化 NH3-SCR反应
• β分子筛,真空浸渍法,铁前驱体: Fe(NO3)3, FeCl3, Fe(C2H5)2,
Fe的理论负载量为 1.0%。
Fe-zeolite: Influence of precursors and preparation method
Fig.3 Catalytic activity of different Fe/β catalyst samples for NH3-SCR
[6].陈银飞等, Chinese Journal of Catalysis 33 (2012) 576-580
• A. Shishkin et al.[7] :NH3-SCR on Fe-ZSM-5 catalysts
• H-ZSM-5; incipient wetness impregnation; procedure
Fe(NO3)3·9H2O, solvent-methanol(Fe-Z1) or 50wt%
methanol in water(Fe-Z2)
• H-ZSM-5; aqueous ion exchange; FeCl2 (Fe-Z3)
• The preparation route of Fe-ZSM-5 is importance for the
activity and selectivity for NH3-SCR, the most active
catalyst is the Fe-Z3 sample.
Fe-zeolite: Influence of precursors and preparation method
[7] A. Shishkin. Topics in Catalysis 56 (2013) 567-575
• The activity and XPS studies show further that a higher
fraction of divalent iron species facilitates the SCR
reaction.
• On the contrary, a higher fraction of trivalent iron species
facilitates the oxidation of NH3.
• It is in agreement with Anunziata’s study that Fe2+ is more
active than Fe3+ for the SCR.
Fe-zeolite: Influence of precursors and preparation method
• The influence of precursors is affect by preparation method.
• Incipient wetness impregnation; Solid-state ion exchange;
aqueous ion exchange
• Precursors: chloride, nitrate, sulfate, acetate. Fe3+
• Questions ?
• Solid-state ion exchange: Replace He by N2?
My opinion and plan
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