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