1.
 O Sorbent gggg -Al Effects of Heat Treatment Condition on Sulfur Removal Capacity of CuO/
 gggg 

 CuO/γγγγ -Al

O

    

^†* **

 

*   

** 

(2001 7 25 , 2001 11 14 )

Effects of Heat Treatment Condition on Sulfur Removal Capacity of CuO/γγγγ-Al

O

Sorbent

Kyung Seun Yoo^†, Sang Done Kim* and Soon Kook Kang**

Department of Environmental Engineering, Kwangwoon University, Seoul 139-701, Korea

*Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea

**Department of Environmental Engineering, Sunmoon University, Asan 336-840, Korea (Received 25 July 2001; accepted 14 November 2001)



  CuO/γ-Al2O₃   
 (300^oC, 500^oC)

! "# $%&'(. )! 500^oC(bulk sulfation), CuO/γ-Al2O₃  
 800^oC*

+ ,-&'. / 0  12&'(. /34   300^oC 56
 700^oC*+ 

7%&8 9+: ; < 12&'(. => ?@ )! > CuSO4A &B CDE SO3-F &B GHE +I JK )! > L+: CuO MNOP &B SO2 JKQ  &B GHE RS (. 800^oC


$\ ]^_ L+: Cu  JK`) +ab . / ; octahedral cdef tetrahedral c g

T CuAl2O₄ CD
  ,-Z[ ,-& RS (. CuAl2O₄ ?@ )! > h)-F CuO/

γ-Al₂O₃ iT$jkd Y&B 7l4+ mkn CuAl2O₄ o`p DRS XRDp P&B qY&'(.

Abstract−Effects of heat treatment temperature and time on sulfur removal capacity of CuO/γ-Al₂O₃ sorbent were deter- mined in a thermogravimetric analyzer with a variation of sulfation temperature (300^oC, 500^oC). At sulfation temperature of 500^oC (bulk sulfation), sulfur removal capacity of CuO/γ-Al2O₃ sorbent increases with increasing heat treatment temperature up to 800^oC and then decreases. At sulfation temperature of 300^oC (surface sulfation), however, sulfur removal capacity of the sorbent remains constant up to 700^oC and then slightly decreases. This is because bulk sulfation advances by SO₃ gas decom- posed from the CuSO₄, whereas surface sulfation goes on by surface transfer of SO₂ via catalytic function of CuO. Sulfur removal capacity of sorbent heated at 800^oC shows a maximum value at the heat treatment time of 12 hr and then decreases with increasing heat treatment time. This is because redispersion of Cu ions is dominant at initial step and then formation of CuAl₂O₄ increases with increasing heat treatment time by the movement of impregnated copper ions from octahedral (Oh) to tetrahedral (Td) site. Bulk sulfation does not occur in CuAl₂O₄ due to the strong bonding of SO₂ with CuO/γ-Al₂O₃ and the existence of CuAl₂O₄ has been confirmed using diffuse reflectance spectra (DRS) and x-ray diffractometer (XRD).

Key words: Sorbent, Calcination, SO₂, Desulfurization, DRS

1.  

      SOx NO_x  ! "#! $%&' ()*[1-5], CuO/γ-Al₂O₃

+,-/./ 01 234 '! 5,! 236   789 :"[6-9].

; CuO/γ-Al₂O₃+,-/./ '1! <=>? @ ABC 7DE F >? G H I"* F% JK)". 90LM &

NO Centi P[10-12]4 Q
@R ./Q
  STU SO3F 7DE VWX 'Y ABVW' >? G !" 0Z[ \ C]* Yoo P[13]4 Q
@R AH^_ >?`a bc de 7D

†To whom correspondence should be addressed.

E-mail: yooks@daisy.kwangwoon.ac.kr

E AB >?%aF surface sulfation, deep sulfation, bulk sulfation

 f FH @gh[ ijkXl 7DE AB >?mT[

" @B
]". 'n <=>?' JKU +,- oS>? mT[

*pkXl 7DE  qrg' Al2(SO₄)₃ sU t5a 1'

u oSN HvwC <=-oS x'y' zHh[ \C]"[6]. 'n Jeong_ Kim[8]4 CuO/γ-Al₂O₃+,- 7{R |[ }F -b kXl SO2-Al₂O₃>?[ ~4 `aOa JK , :€[ *

]".

CuO/γ-Al₂O₃+,-O 7DE AB _wC <=>? G  AHU Q
@R  ‚%ƒ AH Q
@R „…R `a

 † de 7DE ‡ ‚%@bF ˆ
u U". deO ‰ 

@O CuO/γ-Al2O₃ <=Š[ ‹M  „…R †_ `ab c[ a* CuO/γ-Al₂O₃+,- -bbc' <=Š EŒ Ž

 M *p* !".

2.  

2-1.


‰ @ 01 +,- 3 mm pellet ‘ γ-Al₂O₃(Strem Chemical)

 '1 -b]". ’ Cu(NO3) · 3H₂O  “ %a AH

^' a” •Q –—, ˜C n, ™ J$ – ‡ še›

œ γ-Al₂O₃ k ž". Ÿ 70^oCO še›œ ‡ ,1 ' ¡

¢ –W  £¤O 24† Y¥ cb!". cbU +,-

$ g O „…R `a 500-1,000^oC, „…R † 2-170†X

 ˆ
ƒ T¦". TU CuO/γ-Al₂O₃+,- ball mill

g§! n sieving 1-1.41 mm ¨]Xƒ EDX '1 Q

@R ©! AH \C]* -bU +,- |Q ˜ 1 

‡ @Rªa A.A.(Atomic Absorption Spectrophotometer) «%

AHU Q
@R#[ «%]". BET 01 -bU +,-

VWw_ $œ «%]".

2-2.  

‰ @ 01U TGA(TGDTA92 Setaram, France) Fig. 1 a

]". 10⁻⁶g %\T[ ¬ ­ ®[ 01ƒ, ¯TBF

>?° ± ²&N F ³[ ´ µ 15 mm ¶t[ FJ quartz ·[ '1]". >?B ,%zR· q¸X ¹º 

¸X ƒ >? ‡ /»¼ ½¾ basket ¿ÀU +,-

>?u U". „“4 ±F„ 2­X “Á graphite Â&NJ F„ÃF furnace 6Ä Œ `a PID -Nƒ Ås Æ

  ÇÈU".

TGAO =Q
>?[ JK  ½¾ basket 30 mg

 +,- ¿À* 900 cc/min $ ²Rƒ “ >?`aÉ H `a –FÊ". “ >?`aO „6^ gF ¥%


W SO2ªaF 15,000 ppm' a” SO2 ¹º =Q
>?[ , K!". ­ ® Ëuˆ
 PC ¿ +,- <=s Ì[ •Q]".

3.  

<=>? `aˆ
 de ,KU 8 wt% CuO/γ-Al₂O₃ +,- S/Cu Í ¸ Wwr -ÎU Ï=QF› Í, >?† de Fig. 2

 a]". S/Cu Í ÏÐ ­ (1)  •Q)".

(1)

 ­O W +,- >?† dÑ Ëu ҇ƒ, Wo +,- ;Ëu, Co +,-‡ Q
@R Ó^gÌ, Mi iTg

 g^[ ÒÔ". +,- S/Cu Í >?†' –Fk

deO Ï=QF› CuO/γ-Al₂O₃+,- >?  –Fk[

Õ , :". Fig. 2 ÒÖ × Ø' ¡Ù >?`aO S/Cu Í S

Cu--- (W W– _o)⁄M_SO3 W_oC_o⁄M_CuO ---

=

Fig. 1. Schematic diagram of thermal gravimetric analyzer

1. N₂ 7. Blower

2. Air 8. Sample basket

3. SO₂ 9. Balance

4. H₂ 10. Controller

5. Gas chromatograph 11. Buffering line

6. SO₂ trap 12. Thermocouple

Fig. 2. Captured amount of SO₂ and S/Cu mole ratio of CuO/γγγγ-Al₂O₃ sorbent as a function of reaction time with a variation of sulfa- tion temperature.

 40 1 2002 2

 1.0[ ;_* :Xƒ >?`aF –FÚ,” S/Cu ÍF – Fk[ \CÚ , :". '! ‚_ Table 1 a! × Ø' Centi P[10]' -! >?­(9-11)_ Yoo P[13]' -! >?­

(14) ! 7DE  >?G  C!".

>?`a 400^oC 'O ÛÜO Õ , :Ý' CuO/γ-Al₂O₃ + ,- Ï=QF› -Î^' ‹ÞwX %! ß[ 'ƒ ނ*

:". '³4 Q
@R +ÀU Ï=QF› surface transfer[10] 

! 7DE VW =Q
>?' JK" 7DE >?VW Ï

=QF› -Î1^' àáW â 'q >?' HvH ã* ނ

 äå'". <=>? `a 500^oCO >?† 180g' t_!

na %! ® ¬Xƒ HvwX Ï=QF› +,- >

?' JK* :€[ \CÚ , :".

8 wt% Q
@RF AHU 7DE +,- t5 7DE  V Ww[ æ! Q
@R AH^4 5µmol/m²' * Nam_ Gavalas [14]  *U Å,! 7DE Â Ï=QF› -Ί 2µmol/

m²[ æW ‹M -Î^4 7µmol/m²' H Fig. 2 a! 500^oC

<=>?‚_ Ï=QF› -Î^ 15µmol/m² 'ç* :Xƒ è!

HvwC >?' éqU". Koballa Dudukovic[17]4 CuSO4 t5

>?­ (6)  SO3F STê , :€[ -! × :Xƒ Kocaefe P[18]4 SO3  ¾vQ
Æ Ï=QF› -Ί' œu Žq ê , :€[ *! × :". Yoo P[13]4 >?`a 500^oC O >?

­ (16)  SO3 F›F ST* 7DE AB >?' >?

­ (17)  JKN ëœ=Q
>?' JKU"* *]*

'! ìíîïX 7DE ABF HvwX =Q
>? G

 ³[ ëœ=Q
(bulk sulfation) >?X %]"[13].

Fig. 3A 3B „…R `a ˆ
ð T! CuO/γ-Al<sub>2</sub>O<sub>3</sub>+, - >?`a 500^oC(A) 300^oC(B)O =Q
>?[ JKð 

† dÑ S/Cu Í a]". Fig. 3AO Õ , : × Ø'

„…R `a –F,” +,- <=Š4 „…R `a 800^oCÉ H –F]* 900^oCO ñòó ]". Û =Q
>? ` a 300<sup>o</sup>CO „…R `a 800^oCÉH ô õ' 'H IöXƒ

900^oCO Ÿ† <=Š F Ò÷". „…R `a 800^oCÉH

 „w‚  ST CuO islandO ëœ =Q
>? ¹ U øTù°Ú[  CuSO4 ST' 1'u JKN ëœ =Q

>?T' –F ³X 0U". Û „…R `a 900^oC t 5 AHU Q
@R 7DE  >?  ú ûü ‘

ýþQ
ÆC CuAl2O₄ T' JK ³X 0U". Friedman_

Freeman[15] W 7DE VW AHU Q
@R „…R `

aF –FÚ,” distorted octahedral siteO tetrahedral site 'Y ' –F* „…R`a 900^oCO CuAl2O₄ T' ÿçu JK

 ³X *U × :". deO „…R `a 800^oCO ‹M ë

œ=Q
>?' JK ³X 0U".

=Q
>? 300^oC ‚_ W, „…R `a dÑ ˆ
F œu Ò H I* :X „…R `a 800^oCÉH Ÿ† <=Š 

F Ò * 900^oCO <=Š F " –Fk[ \CÚ , :". ' „…R `aF –Fk de „w‚ ! Q
@R . /øT  VWw F Y>) äåX 0U". VW=

Q
>? :NO ./øT  Q
@R øTùO JK

VW =Q
>?va  Ò * VWw  STU SO3

-Î1^  Ò  äå'".

„…R `a ˆ
 dÑ CuO/γ-Al2O₃ +,- X-ray ™
g 

‚_ Fig. 4 a]". AHU Q
@R t5 7DE AB

 VWw 100 m²/g[ æX @Rk^ 4 wt%'qO XRD  ' 2θ ß[ æX 35.6, 36.7, 38.8O Ò u U". Fig. 4 a!

× Ø' „…R `a 700<sup>o</sup>C ‚_" „…R `a 800^oCO AH U Q
@R „w‚  35.6_ 38.8 Q
@R  ' –F

 ³[ \CÚ , :". è! „…R `a 900^oCO CuAl2O₄ mT  ' 36.9O íu –F ³X \C)".

„…R `a dÑ CuO/γ-Al₂O₃+,- diffuse reflectance spectra

‚_ Fig. 5 a]". Q ‚þ! ¾v'` t5 ¾v'`

[  Q @b deO '°' O "çu Ò u U

". ¾v'`[  Q'`' 4(C tetrahedral R t5 ' Table 1. Sulfation reaction mechanism of CuO/γγγγ-Al₂O₃ sorbent

Reaction mechanism Reference

MeO+SO₂(g)↔MeSO₃^*(ads) O₂(g)↔2O^*(ads)

MeSO₃^*(ads)+O^*(ads) ↔MeSO₄(s) MeSO₃^*(ads)↔MeSO₃(s) MeSO₃^*(ads)↔Me^*(s)+SO₃(s) MeSO₄(s)↔MeO(s)+SO₃(g) 2Me^*(s)+O₂(g)↔2MeO(s)

(1) (2) (3) (4) (5) (6) (7)

Koballa and Dudukovic [17]

SO₂(g)↔A+SO₂(ads) CuO+SO₂(ads)↔CuO-SO₂(ads) CuO+CuO-SO₂(ads)↔CuSO4(s)+Cu Al₂O₃+CuO-SO₂(ads)↔Al₂O₃-SO₃(s)+Cu Cu+O₂→CuO

(8) (8) (10) (11) (12)

Centi et al. [10]

CuO+SO₂+1/2O₂→CuSO₄ Al₂O₃+CuO-SO₂→Al₂O₃-SO₃+Cu Cu+O₂→CuO

CuSO₄→CuO+SO₃ Al₂O₃+SO₃→Al₂O₃-SO₃

(13) (14) (15) (16) (17)

Yoo et al. [13]

Fig. 3. S/Cu mole ratio of CuO/γγγγ-Al₂O₃ sorbent as a function of reac- tion time with a variation of heat treatment temperature: (A) bulk sulfation(T_s=500^oC), (B) surface sulfation(T_s=300^oC).

°4 1,300-1,600 nm'ƒ Q'`' 6(C octahedral R t5 600-800 nmO Ò u U"[16]. γ-Al₂O₃ AHU Q
@R t5 tetralhedral R 1,415 nmO \Cƒ, octahedral site 740 nm

O \CU". Fig. 5 a! ‚_ Ø' AHU Q
@R „…R

`a –F,” 1,415 nmO  a –F* 740 nm

O  a k[ \CÚ , :". „…R `a 1,000^oC‚_

 W tetrahedral R  4 ¡¢ 0eH* octahedral R   shoulder Â' u ƒ ' CuO CuAlO2þÆ  _ /5 z0!

‚_ ¹* :". '! ‚_ „…R `aF –Fk de „…R

`a 900^oCÉH Q
@R ŒF octahedral RO tetrahedral

R 'Y CuAl2O₄ ›@bF STƒ 1,000^oCO * q>?  CuAlO2
þÆ' STh[ E!".

„…R `a 800^oCO „…R † dÑ CuO/γ-Al₂O₃ +,-

Ï=QF› -Ί[ <=>?`a 300^oC 500^oC M Fig. 6

a]". <=>?`a 500^oC t5 W „…R † 12†[

æX +,- <=Š4 ‹Mß[ C n Û 'qO „…R

† de Âu ]". Û <=>?`a 300^oC t5

 „…R † de /5 Efu  ‚_ ҇)". <

=>? `a 500^oC t5 „…R † 12†O ‹M <=Š[

C 'z AHU Q
@R „w‚_ Q
@R octahedral  RO tetrahedral R R'Y' k N  äåC ³X

0U". „w‚ ! CuO island T4 ëœ=Q
>?

" zRH octahedral RO tetrahedral R 'Y 

CuAl₂O₄F ST ³4 CuSO4 Al2(SO₄)₃ ST ¡¢ 2µu   Ru 1u U". deO 800^oC ‚_O Õ , : ×

 Ø' +,- ‹w „…R †4 12†C ³X 0U".

Fig. 74 CuO/γ-Al2O₃ +,- „…R † dÑ ¸ Wwr Ï=

QF› -Ί[ VW =Q
>?_ ëœ =Q
>?X @g „ …R `aˆ
 de a! ‚_'". ëœ =Q
>?' JK

Fig. 4. XRD spectra of heat treated CuO/γγγγ-Al₂O₃ sorbent.

Fig. 5. Diffuse reflectance spectra of heat treated CuO/γγγγ-Al₂O₃ sorbent.

Fig. 5. Diffuse reflectance spectra of heat treated CuO/γγγγ-Al₂O₃ sorbent.

Fig. 6. Sulfur removal capacity of CuO/γγγγ-Al₂O₃ sorbent heat treated at 800^oC as a fuction of heat treatment time with a variation of sulfation temperature.

 40 1 2002 2

<=>? `a 500<sup>o</sup>C ‚_ „…R `a –F,” +,- Ï

=QF› -Ί' Žq)Xƒ 700^oCÉH „…R †' –F

a +,- <=Š' Î %u zH)". Û „…R `a 800^oCO „…R†' –Fk de AHU Q
@R ocathedral

RO tetrahedral R R'Y ! CuAl2O₄ ST' J KN +,- <=Š4 OOó ]". VW =Q
>?' J K <=>? `a 300<sup>o</sup>C ‚_ „…R `a 700^oCÉH +,-

 <=Š' Î ˆ
 'H IöXƒ „…R `a 800^oCO <

=Š –FF Ò÷". Fig. 7O Õ , :Ý' VW =Q
>?

:NO ¸ Wwr Ï=QF› -Î^4 Å,! 7DE Â -Î^

2µmol/m²[ H I* :Xƒ è! 800^oC „…R  STU CuAl₂O₄ ! +,- <=Š F Ò H I* :€[ Õ , :". '! ‚_ VW =Q
>?_ ëœ =Q
>? ìíîï õ' C ³X ëœ =Q
>?O CuAl2O₄ST 

ëœ =Q
>?[ za CuSO4 ST' 2µN HvwC A B >?' -!HÂ VW =Q
>?O Ï=QF› >?' CuO, CuAl₂O₄@' JK äå'"[9].

4.  

CuO/γ-Al₂O₃+,- „…R `a † dÑ Ï=QF› -Î

Š EŒ Ž[ „6^g '1 *p]". +,- „ …R `a –FW AHU Q
@R ogQ_ k ‚>?' JKƒ ëœ =Q
>?T' –F]". „…R `a 800^oCO

‹M ëœ =Q
>?T' Ò÷Xƒ 900^oC'q *`O Q

@R 7DE  *q>?  ST CuAlO2  ë

œ =Q
>?T' ñòu ]". ‹w „…R `a 800^oC O „…R †[ –FW „…R † 12†ÉH „w‚ 

! >?T –FF Ò * Û 'q †O OOó ST

CuAl₂O₄  >?T' u U". VW =Q
>?4 „… R † Ž[ Î H IöXƒ ' SO2 >?' CuO, CuAl2O₄

@' JK äåX 0U". „…R `a 800^oC 'O

CuAl₂O₄ STvaF `a  de ñòu  äå „ …R †[ –Fða ëœ =Q
>?_ VW =Q
>? ¡¢ >

?T ˆ
F Ò H Iö".

' å4 2000La üM ‡@  @) Xƒ ' 0î".



1. Kohl, A. L. and Nielsen, R. B.: “Gas Purification,” 5th ed., Gulf, Houston, Texas(1997).

2. Chu, K. J., Yoo, K. S. and Kim, K. T.: Materials Research Bulletin, 32, 197(1997).

3. Lancia, A., Musmarra, D. and Pepe, F.: Ind. Eng. Chem. Res., 36, 197(1997).

4. Lee, J. B. and Kim, S. D.: Chem. Eng. J., 69, 99(1998).

5. Wallin, M. and Bjerle, I.: Chem. Eng. Sci., 44, 61(1989).

6. Yoo, K. S., Jeong, S. M., Kim, S. D. and Park, S. B.: Ind. Eng.

Chem. Res., 35, 1543(1996).

7. Jeong, S. M., Yoo, K. S. and Kim, S. D.: HWAHAK KONGHAK, 35, 116(1997).

8. Jeong, S. M. and Kim, S. D.: Ind. Eng. Chem. Res., 36, 5425(1997).

9. Waqif, M., Saur, O., Lavelley, L. C., Perathoner, S. and Centi, G.: J.

Phys. Chem., 95, 4051(1991).

10. Centi, G., Riva, A., Passarini, N., Brambilla, G., Hodnett, B. K., Del- mon, B. and Ruwet, M.: Chem. Eng. Sci., 45, 2679(1990).

11. Centi, G., Passarini, N., Perathoner, S. and Riva, A.: Ind. Eng. Chem.

Res., 31, 1947(1992).

12. Centi, G. and Perathoner, S.: Ind. Eng. Chem. Res., 36, 2945(1997).

13. Yoo, K. S., Kim, S. D. and Park, S. B.: Ind. Eng. Chem. Res., 33, 1786(1994).

14. Nam, S. W. and Gavalas, G. R.: Appl. Catal., 55, 193(1989).

15. Friedman, R. M. and Freeman, J. J.: J. Catal., 55, 10(1978).

16. Hierl, R., Knozinger, H. and Urbach, H.: J of Catal., 69, 475(1981).

17. Koballa, T. E. and Dudukovic, M. P.: AIChE Symposium Series, 73, 199(1978).

18. Kocaefe, D., Karman, D. and Steward, F. R.: AIChE J., 33, 1835 (1987).

Fig. 7. Sulfur removal capacity and sulfate on alumina as a function of heat treatment time with a variation of heating temperature(
,: 600^oC, ,: 700^oC, ,: 800^oC.