(c) i ill mHH~-E~ i, J,,., D \ \ | • u I i L o o-° I FiEm-e 12. Y~S spectTa of commercial ]~rchemie ~talyst in Fe 21) region. (~) fol]o~-mg ca]dnat]on for 16 ~ a~ 3{10 ~C~ (b) follo~ e.~'posure ot" (~) ~o CO ~t 300 °G; (¢) follo~'mg e,l~o~e of (a) to 112 at 300 °C. ,=)IJ ~le llescrip~imc ] i i ' ' 'i i i= i 1 | i ~.0 B~ ~ ~ ~.0 Figure 13. XPS spectra of commercial Ruhrc.hemie cazaly~ in Si 2p region. (a) foDowing calch~tion for 16 ba-s at 300 =C; (b) following exposure of (a) to CO at 300 °C; (c) fonowi~ exposure of (a) to }t_- at 300 °C. 67 . Ill II l- i j j (0) t ['" t / 'Fi~.u'e I4. XPS spectra of" con'~n~da.1 R",z~daemie cat ~lyst in If 2p ant1. C ls ~regions. (a} following c~c~ation fo~ 16 h~s at 300 °C; (b) follo~i~g e~os~Jre of (a) to CO at $00 • C; (c)fo]]owh~g e.~os'=e of (a) to ~ at 300 °C. | i 4 | / \ - .¢~\ .,- -~ I n i i i | i Fi~uTe 15. XPS spectra of commerded Ru]u'chemie catalys~ in O Is region. (a) following calcination for 16 hrs a~ 300 ~C; (b) foUo~ring ~posare of (a) to CO at 300 °C; (c) followiag ~os~re of (a) to ~I= at 300 °C. Lsmiple De,,~,,t'~tion: ~ ~ i ' " i l "= i ! ' '" 4 i i i i ms.o Bin~g ~,,,gy Icy) ~.o TE~S/~( I]~SITY Figure 16. XPS spectra of comznerdal I~u]~chem~e catalyst in Cu 2p region. (a) foUowing calcination for 16 ]~s at 300 oC; (b) fol]o~;~g exposure of (a) to CO at 300 oC; (c) following exposure of (a) to H2 a~ 300 °C. 7o cn mm r- 13 L=. oJ Q s,. V q~ i'- 0 fn a o i ,, i1, m sl ,, r i . l " I ' i " I " I " I " I " | • I • I . I • l a I I . I ~ I 0 200 400 600 800 Time (rain) Figure 17. Isothermal reduction pro~e in ~I~ for calcined {16 hrs in O~ at 300 °C) ~rnp|e of 2,5 wt % Fe/Si02. 71 tJ~ e,mmmD c- b 1:I Q t:1 m c 0 CL (jr} Q,) rv- C~ F , , i ii ' I " I " I " I " I " I ' I ' • i, . __ .= l I v I , T, , 1 , I l l , I , ! 0 200 4-00 600 800 Temperature (Oc) Figure 18. TPR profile in H2 at 20 °C/miu for saznple of 25 wt % Fe/Si02 that had been pre~ously txeazed for 15 bxs in H2 at 300 "C. ?2 580B I ( I ) 738FEI Reg i on # o~ e Scans 58 Flood Gun 2.8 E.V. 78S .5 S . • ':.;;::-:~. . j-t l I " I I I I I I 74e.8 %. ; :;:/' I I 71~.0 Figx~e 19. XP5 spectra of 25 "~1% Fe/SiO2 in Fe 21) region following calci~adon fox 16 h~s a~ 300 °C and subsequent txeatment in H2 for 16 ]~'s at 300 °C. A o f• t n ~ m. ±~ ~ .I !. . I" m. omm !. _L__ , . ~ ~ ~=-~_~~ I m • " . ] ! ! t ! "! • " l-:. :-" p~ I m 2500 2000 1800 1600 Wavenumber (cm "1) 1300 Fi~e 20. FT-m ~ec~ra ofNO a~orb~ a~ 25 °C on 25 ~-t % Fe/$iO~ ttmt had been r~cined for 16 ]lrs at 300 °C and subsequently z~-eatect in ]~z for 16 ]n~ at 300 °C. ~rh~ uppermost spectrum was obtaiu~ followiug exposure of the sa~np]e to 10 tort of ~qO for 15 rain, foUowed by e~cuation. T/~e second spectrum was obtained immediately a~te~ admission of 10 torz of 02 at 25 °C. The ~'ema~g spectra ~'ere then obtained at 15 in~u intervals in the ¢ontinuiug presence of gaseous Oz. "*'t ¸ " .11 >~ - ~ °- .,~. c._ ~ - ~ ~ ~ C,I . - .__]_m_= ' =F ':' ~R i ,o p ,° m m o. . • t - • t- - -r ~t t t ~ t' t r" L_ ~- I" "" t'~''-" 2500 2000 1800 1600 -~-~ ! • t- T WaveruJmber (~-I) , ° , "i " 'T- -T" t i m | : • 1300 Figure 21. FT-IR spec~m of NO a~orbed at 25 °C on 25 ~ % Fe/SiOz containing 1 ~t % K that had been calcined for 16 ]~'s st 300 °C and subsequently treated in H2 for 16 hrs at 300 °C. The uppermost spectrum was obt.zined following exposure of the sample to 10 ~r of NO for 15 m~ followed by e~cua~on. The second spectrum was obtalned immediately after admission of 10 tort of 02 at 25 °C. The r~ spectra weTe then obr.~ined az 15 mJn intervals in the continuing presence of gaseous 02. . 600 80 0 Temperature (Oc) Figure 18. TPR profile in H2 at 20 °C/miu for saznple of 25 wt % Fe/Si02 that had been pre~ously txeazed for 15 bxs in H2 at 300 "C. ?2 580 B I ( I ) 738FEI. 580 B I ( I ) 738FEI Reg i on # o~ e Scans 58 Flood Gun 2 .8 E.V. 78S .5 S . • ':.;;::-:~. . j-t l I " I I I I I I 74e .8 %. ; :;:/' I I 71~.0 Figx~e 19. XP5. ' i " I " I " I " I " | • I • I . I • l a I I . I ~ I 0 200 400 600 80 0 Time (rain) Figure 17. Isothermal reduction pro~e in ~I~ for calcined {16 hrs in O~ at 300