Dong Xuesong Fe-zeolite: Influence of precursors and preparation method

Anunziata et al. [1] : i-C 4 H 10 -SCR on Fe/ZSM-11 catalyst. NH 4 -ZSM-11; Wetness impregnation; Precursors FeSO 4 (Samples: A, B. Fe content: 1 and 3 wt%) and Fe(NO 3 ) 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 samples A, B and C

XRD result indicated only in the sample C: hematite phase ( ɑ -Fe 2 O 3 ) 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 Fe 2+ while Fe 3+ is less active for the SCR of NOx with i-C 4 H 10. 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 Co 2+ cationic ion exchange position. while Ac leads to most isolated Co 2+ However, Kawi et al. [3] observed no difference between Co(NO 3 ) 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 CH 4 on Pd/Al 2 O 3 Chloride, nitrate or acetate; Impregnation PdCl 2 : much better acitivity especially at high temperature. Cl - migrate to the active Pd 2+ 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(NO 3 ) 3, FeCl 3, Fe(C 2 H 5 ) 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 NH 3 -SCR [6]. 陈银飞等， Chinese Journal of Catalysis 33 (2012)

A. Shishkin et al. [7] :NH 3 -SCR on Fe-ZSM-5 catalysts H-ZSM-5; incipient wetness impregnation; procedure Fe(NO 3 ) 3 ·9H 2 O, solvent-methanol(Fe-Z1) or 50wt% methanol in water(Fe-Z2) H-ZSM-5; aqueous ion exchange; FeCl 2 (Fe-Z3) The preparation route of Fe-ZSM-5 is importance for the activity and selectivity for NH 3 -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)

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 NH 3. It is in agreement with Anunziata’s study that Fe 2+ is more active than Fe 3+ 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. Fe 3+ Questions ? Solid-state ion exchange: Replace He by N 2 ? My opinion and plan