Catalytic reforming of methane with carbon dioxide on reduced perovskite-type oxides

Article abstract of DOI:10.1246/nikkashi.2000.613

The reforming reactions of CH₄ with CO₂ diluted with He were carried out over the cobalt catalysts prepared from the perovskite structural oxides, LnCoO₃ (Ln = La, Pr, Nd, Sm, Eu, Gd, Er, and Tb) and the relationship betwe

Full text of DOI:10.1246/nikkashi.2000.613

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2000 The Chemical Society of Japan
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}ðÆè °ÄG}\ÊÁ«É¢ğ¢µ½‹ÊCEuCoO3 Í LaCoO3, SmCoO3 æèÒ³³êâ·
-CÒ³ãÌ Co/Eu2O3 G}\ÊÉà®Ro‹gƆEsE€ªmFÅ«C‚ˆ«Ì´öÉA¹çê
éD¯lÈÒ³ðºCSmCoO3 G}Í Co ª\ªÒ³³êÈ¢½ßC‚ˆ«ÉÈçÈ¢DܽCCo/
Eu2O3 ÉÍärIá·Æ‚·æÅ--ñíÞ̈«_ª¶ÝµCSmCoO3 G}ÉÍ1073 K Æ¢¤‚·
æÅ--ˆ«_µ©¶ÝµÈ¢½ßC873 K Å͈«ð¦³È¢DÒ³ªðãÌ LaCoO3 G}Í CO2
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» 1 Å éD»Ì½ßC±Ì½žÍꢀfÆ CO 𽞳¹ÄL@
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LnCoO3(LnL a, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb)̲»ÍÈ
ºÌè‡ÅsÁ½DܸCLn Æ Co ̂‹äª 1F1 ÉÈéæ¤
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Í1273 K)Å 5 žÔĬµ½De펿ð60
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½žÍåƵĽž·x 873 K ÅsÁ½D´¿¨æѶ¬¨
̪ÍÍKXN}gO‰t(‡Ã GC–8A)ðp¢½D
CH4, CO2 Ì]»¦¨æÑ CO, H2, C2 »‡¨ÌIð¦ÍŸ®É
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CH4(CO2)]»¦
[(CH4(CO2)Ÿ‹Ê)|(¢½ž CH4(CO2)ÌÊ)n
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CO Ið¦(CO ¶¬Ê)/(½žµ½(CH4{CO2 Ê))
H2 Ið¦(H2 ¶¬Ê)/2~(½žµ½ CH4 Ê)
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ú { ª õ FT–IR550 ) C X ü õ d q ª õ ( XPS A ‹ o b N
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Fig. 1 Comparison of activity of the Co/Ln2O3 catalysts.
Catalyst weight: 1 g, gas ‰ow rate: CH4CO210mL
min|1; He60mL min |1, reaction temperature: 873
K, reduction conditions: H2 ‰ow; 50mL min |1 for 3 h
at 773 K.
XPS ªè‹ÊÉæé\ʳfÌÊðèÊIɁ߽vZ®8)Í
CiHi/(SiETiENi)
Co/La2O3 G}Å͈«ªS-©çêÈ©Á½DêûC‰“^m
Chã¼O‹[vÌ Eu ©ç Yb ÜÅÌe³fðÜÞÒ³ªðG
}Å͂¢è툫𦵽DÁÉ Co/Eu2O3 G}ÅÍ CH4,
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éD±±Å
CiFi ³f¬ªÌèÊlCHiFªè³fÌs[N‚³CSiFªè
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fÌ Sweep ñ”D
Èã̽ž‹Ê©çÒ³ªðµ½ Co/Ln2O3 G}̈«Í Ln
³fÌíÞÉæÁÄ·ªå«¢±Æªí©Á½D»Ì´öð†¾
·é½ßɈ«ª‚¢ Co/Eu2O3 G}CóyÞ³fÔ†Í Eu Æ
×ÅC½žˆ«É·ð¦µ½ Co/Sm2O3 G}¨æѽž·x 873
K Žžˆ«ªÈ©Á½ Co/La2O3 G}ðÆè °ÄŸ¢ðsÁ
½D
S
S
Xi÷Ci/ Ci÷ (XiFä¦lC CiC1{C2ċv)
CO2 zꢀ¸·E£(TPD)ªèÅͪèÇàɎ¿(0.5 g)ðü
êꢀfÅÒ³ãC873 K Å 1 žÔECµ½ãCº·Å CO2 ðz
ꢀ³¹CHe µÍC† 5 K/min ̬xŸ·³¹½DE£¨Í}
CNZ“T[KXAi‰CU[(‡Ã»ìŠ M–200)ªÍ•u
ÉæÁÄ 3 ªÔuÅT“vŠ“Oµè«CèÊðsÁ½D
C.B Co/Eu2O3 Æ Co/Sm2O3 G}̟¢
C.B.A Ò³·xÌe¿FCo/Eu2O3 Æ Co/Sm2O3 G}Éε
ÄÒ³ªðÌ·xͽžÌˆ«Ée¿ðyÚ·Æl¦C±±ÅÒ
³·xðϦĽžˆ«Ìϻ🢵½D
C ‹ÊÆl@
C.A eG}̽žˆ«
Šè·xÅĬµ½ LnCoO3(LnLa, Pr, Nd, Sm, Eu, Gd, Dy,
Er, Yb)¡_»¨Ì‹»ŠÍ XRD @Éæè¯èµ½D»Ì‹
ÊCeŽ¿Í¢¸êà ABO3 ؍uXJCg\¢Ì¡_»¨Æ
ÈÁÄ¢½ªCEr Æ Yb Ìê‡Í Ln2CoO4 ¡_»¨Æ Ln2O3 _
»¨¨æÑ Co3O4 ̊àÏ@³ê½D
\
SmCoO3 Æ EuCoO3 ¡_»¨ðp¢Ä573 1073 K ÌÒ³·
xÅ 3 žÔꢀfÅÒ³ˆµCXRD ªèðsÁ½DXRD ªè
̋ÊÍ¢¸êÌ·xɨ¢Äàà®Ro‹gÆ Eu2O3 ¨æÑ
Sm2O3 ª¯èÅ«½D
ÙÈé·xÅÒ³µ½¼G}ðp¢ÄèíÉÈÁ½Æ«Ì½ž
ˆ«Í Fig. 2 ɦ·DȨ½žÍ 4 žÔsÁ½DG}ðÒ³µ
È¢ê‡C¼G}Æཞˆ«ð¦³È©Á½DEuCoO3 G}Ì
eG}ð½žOÉ773 K Å 3 žÔꢀfÒ³ˆðsÁ½Dꢀf
Ò³ã̎¿ð XRD Ū赽‹ÊC¢¸êàà®Ro‹gÆ
óyÞ³fÌ_»¨©çÈé±Æª©çê½(ȺꢀfÒ³ªð
µ½G}ð Co/Ln2O3 ƪL)D
ê‡CÒ³ˆÉæ舫ªo»µCÒ³·xð573
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973 K É
ϦÄཞÌè툫ÉÍå«È·ª©çêÈ©Á½D½ž·
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·é CH4 ÉæÁÄRo‹g_»¨ªÒ³³êé½ßÆl¦çê
éD±êÍãqÌæ¤É EuCoO3 ª SmCoO3 Éä×ÄÒ³ªð
³êâ·¢½ßÅ ë¤D
Fig. 1 ÍCãLÌ Co/Ln2O3 G}ðp¢Ä½ž·x 873 K ɨ
¯é½ž‹ÊÅ éD¶¬¨ÍC·×ÄÌG}ɨ¢Ä H2 Æ
CO ¨æÑ÷ÊÌ H2O Å Á½DeG}̽ž‹Ê©ç Sm Æ
Eu ð«ÉµÄÁ¥Iȋʪ¾çê½Düú\´qԆ̬³
¢O¼O‹[v̆ŠPr, Nd, Sm ðÜÞ Co/Ln2O3 G}Ìê
‡C½ž‰úÉ CH4 Æ CO2 Ì]»¦(Ⱥˆ«ÌÚxÆ·é)ð
¦µ½ªC30 ªãɸˆµCè툫;çêÈ©Á½DܽC
êûCSmCoO3 G}ÅÍ1073 K Ⱥ̷xÅÒ³·éê‡C
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Fig. 2 The relationship between reduction temperature and
conversion over Co/Sm2O3 and Co/Eu2O3 catalysts.
Catalyst weight: 1 g,gas ‰ow rate: CH CO210 mL
4
min|1; He60 mL min|1,reaction temperature: 873
|1
K,reduction conditions: H ‰ow 50 mL min for 3 h.
2
No: No reduction treatment.
Fig. 3 EPMA image of ò Co/Sm2O3 and ò‚ Co/Eu2O3.
|1
ð1073 K Ƃ-·éÆ Fig. 2 ɦ·æ¤ÉêèȈ«ª©çê
½D±êÍ1073 K ‚·ÅÌ SmCoO3 ÌÒ³ªðª\ªÉisµ
Ä¢é½ßCG}ªˆ«ð¦µ½Æl¦çêéDµ©µCÒ³ª
s\ªÈç_»Ro‹g̶ݪ©çêé͸ŠéªCXRD
̋ÊÅÍá·ÅàÒ³ªðãÌ SmCoO3 G}Íà® Co Æ
Sm2O3 ̋»s[Nµ©©çêÈ¢D±êÉ¢ÄÍÒ³ªð
ªs\ªÈ SmCoO3 G}ÅÍ_»óÔÌRo‹gª³è`óÔ
ÉÈÁÄ¢é½ßCXRD ̋ʩç_»Ro‹gª©çêÈ©
Á½Æl¦çêéD
Reduction condition: H2 ‰ow 50 mL min for 3 h at
773 K.
Table 1 Comparison of composition ratios of catalyst sur-
face by XPS
Catalyst
Ln(÷)
Co(÷)
O(÷)
EuCoO3
Co/Eu2O3
SmCoO3
18
42
20
10
29
20
8
62
50
60
77
61
a)
20
13
10
a)
b)
Co/Sm2O3
Co/Sm2O3
ܽCEuCoO3 ð773 K ÅÒ³ªðµ½ą̀æÑ SmCoO3 ð
1073 K ÅÒ³ªðµ½àÌÌ XRD ªè‹Êæè Co ̱qað
ß½Æ±ëCOÒÍ19.2 nmCãÒÅÍ20.3 nm Åå«È·Í
©çêÈ©Á½DFig. 2 ̼Ò̽žˆ«ðärµÄOÒÌûª
ãÒæèí¸©É‚©Á½DȨCSmCoO3 ð773 K ÅÒ³ªð
µ½àÌÌ XRD ªè‹ÊÅÍà® Co Ìs[Nªñíɬ³
-C±qaðZo·éÌÍ¢ïÅ Á½D
a) After reduction at 773 K.
b) After reduction at 1073 K.
è¼G}̬ªðªÍµ½‹ÊÅÍCÇ¿çàÊ_IÈg¬Ì
CoFLn ª 1F1 ÉÛ½êĨèCµ½ªÁÄ Co/Sm2O3 G}Ì
ûª Co/Eu2O3 G}æèRo‹gª\ÊÉZkµÄ¢éÆ¢¦éD
XPS @ªÍ©ç\ʳfg¬ðß½‹Êð Table 1 ɦ
·D»Ì‹ÊÅÍÇ¿çÌG}àÒ³OÌyuXJCg\¢æ
è LnFCoFO ä(LnSm,Eu )ÍÙÚ 1F1F3 Å éªCŊ
Ò³ªðãCG}\Ê̳fÌg¬äÉå«È·ª»ê½DCo/
Sm2O3 G}ÅÍ\ÊÌ Co/Ln äÍ Co/Eu2O3 G}Ì»êæèå
«¢DܽCO/Ln äÍ Sm ðÜÞG}Ìûª Eu ðÜÞG}æ
袸êÌÒ³ˆ·xÌê‡Åàå«¢DO/Eu äÍ1.2ÅC
EuCoO3 ÌÒ³ªðžçê½ Eu2O3 Ì O/Eu1.5 ÈãÉ Eu
C.B.B EPMA, XPS ̋ÊFEPMA,XPS \ʪÍÉæèÒ
³ãÌG}\ÊÌRo‹gÌóÔ¨æÑ´qäð²×½‹Êð
Fig. 3,4 Æ Table 1 ɦ·D
773 K Ò³ã̼G}Ì EPMA \ʪÍðsÁ½‹Êð Fig.
3 ɦ·DFig. 3òÍ Co/Sm2O3 G}ÌCFig. 3ò‚ Í Co/Eu2O3
G}Ì\ÊÉ éRo‹g̪z𦵽àÌÅ éD}†C’
F”ªªRo‹gð¦µÄ¢éDCo/Sm2O3 G}Í Co/Eu2O3 G
}ÉäגF”ªª½-C±ê͎¿\ÊÉãÒæèàRo‹g
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EuCoO3 Ž¿É©çêé1134.3 eV Ì©›Gl‹M[lÍ؍
uXJCg\¢Ì Eu 3d5/2 ÉîÃ-s[NÅ éDEuCoO3 ð
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¨ðÒ³ªðŶ¶½óyÞ_»¨Í–î«Å é½ßC½ž†
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·xð °C¸·E£³¹½‹Ê𦵽àÌÅ éDCo/Eu2
O3 G}ÅÍ613 K, 838 K, 973 K ÉOÂÌE£s[Nª©çêC
Co/Sm2O3 G}ÅÍ623 K, 958 K ÉñÂÌE£s[Nª©çê
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µÄ¶¬µ½ Eu2O3 ¨æÑ Sm2O3 Ézꢀµ½ CO2 ÌE£Éæé
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à620 K tßÉ CO2 ÌE£s[Nª©ç꽩çÅ éD973 K
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íêéD
Èã̄ªðm©ßé̽ßÉ XPS ªè©çe³fÌ©›G
l‹M[Ìlðß½DCo/Eu2O3 G}ÅÍà® Co 2p3/2 ÌÁ¥
IÈ©›Gl‹M[Ìs[N(7 7 8 eV)8)10)ªmF³ê½DêûC
Co/Sm2O3 G}ÅÍ Co 2p3/2 Ìs[NÍ780 eV É»ê½D±ê
Í Co2{ ÉîÃ-s[NÅ éÌÅ 7 7 3 KÅÒ³µÄ¾çê½
Co/Sm2O3 G}Ì\ÊÌRo‹gÍ_»óÔÉÈÁÄ¢é±Æª
¦´³êéD³çɪè©ç¾çê½s[N𪣈·éÆà
® Co Ìs[N(7 7 8 eV)Í©ç꽪Cs[N-xðär·éÆ
»Ì„‡ªñíÉ-È¢DG}Ì\ÊÍ_»óÔÌRo‹gªå
ɶݵĢé±Æªí©Á½D
CO2 ÌE£Ì٩ɼG}Æà H2O, CO ÌE£s[Nª©ç
ê½(ªÍãÌ´öÅe»‡¨Ì´xªÙÈé½ßC}ÍèÊI
ÈàÌÅÍÈ¢)ªCCo/Eu2O3 G}ÅÍ Co/Sm2O3 G}ÆÙÈ
è503 K tßæ肷ɊéÜÅ CO ̶¬ª©çêéDG}\
ÊÉzꢀµ½ CO2 ª CO2¨CO{O ̽žÉæÁÄ CO ª¶¬µ
½Æl¦çêéDܽCH2O ̶¬à©çêéD±êÍ°ç-
Ò³žÉG}\ÊÉzꢀµÄ¢½ꢀfª CO2 Ìð£Éæ趬
µ½_f´qƽžµÄ¶¬µ½Æl¦çêéDêûCCo/Sm2
O3 G}Åà CO ̶¬ªFßçêéDCo/Eu2O3 G}Æ Co/Sm2
Fig. 4 Í EuCoO3 Æ SmCoO3 ¨æÑeXðÒ³ˆµ½Ž¿
†ÌóyÞ³fÌ XPS ªè‹ÊÅ éDSmCoO3 Ž¿É©çê
驛Gl‹M[1081.8 eV Í؍uXJCg\¢ðÆÁ½Æ«
Ì Sm 3d5/2 ÌlÆêvµ½DܽҳˆŽ¿É©çêé
1083.3 eV ÌlÍ Sm2O3 Ì Sm 3d5/2 Ì©›Gl‹M[əµ¢
lÅ Á½D

ú»C2000, No. 9 àE³äE™RE¼cCgcFҳ؍uXJCg^¡_»¨G}Éæé^“Æñ_»YfÆ̽ž
617
Fig. 5 TPD proˆles of CO2 adsorbed over Co/Eu2O3 and Co/Sm2O3 catalysts.
Temperature was raised with the rate of 5 K min|1
.
›: CO, œ: CO2, ¡: H2O.
O3 G}Ì CO ̶¬Jn·xÍ»ê¼ê503 K Æ573 K Å èC
Co/Eu2O3 G}Ìûª CO2 Ò³\ÍC½ž«ª‚¢Æ¢¦é11)D
C.C Co/La2O3 G}̟¢
_–ÉA®13)14)Å«éD
ò‚ÌòåÍ LaCoO3 ðÒ³ªðµ½àÌCòAÍò@É CO2 ň
B
@
µ½àÌCòÍòð½žÉp¢½ãÌG}ÌXyNg‹Å éD
CO2 ˆµ½ą̀æѽžã̎¿\ÊÉY_–ª`¬³ê
Ä¢é±Æª©çêéD
Ò³Oã¨æѽžOãÌ Co/La2O3 G}Æ Co/Eu2O3 G}Ì
XRD ªÍ‹Êð Fig. 6 ɦ·Dò Æò„ ͈OÌ LaCoO3 Æ
EuCoO3 G } Ì XRD Ì ª Í ‹ Ê ð ¦ · D ò‚ C òꢀ Í LaCoO3,
EuCoO3 G}ð773 K ÅÒ³ªðµ½G}Å èCòƒ(f)ͼG
}ð873 K Žž³¹½Æ«Ì XRD ªÍ‹ÊÅ éDFig. 6 Ì
XRD vtB[‹É©çêéæ¤ÉCCo/La2O3 G}Í CO2 Æ
̊ÝìpªÅà--C½žã̎¿É¨¢Ä La2O2CO3 \¢Ì
Y_–̶¬Æ_»Ro‹g̶¬ªmF³ê½DY_–̶¬
͉“^mCh_»¨Ì†CLa2O3 ̖Åà-¢12)±Æª
´öÆÈéD»ÌY_–̶¬ÉæÁĽžªjQ³êCCo/
La2O3 G}͈«ð¦³È¢Æl¦çêéDY_–̶¬·xð
²×é½ßÉ\ÊÉzꢀµ½ CO2 Ì FT–IR XyNg‹¨æÑM
dʖ¦·M(TG–DTA)ªèðsÁ½D
òƒÍ EuCoO3 ð LaCoO3 Ìê‡Æ¯lɈµ½Æ«ÌXy
Ng‹Å éD©çêéæ¤É Co/Eu2O3 Ìê‡ÉÍCCO2 Ž¿
¨æѽžã̎¿Ç¿çÉàY_–Ì`¬ÉîÃ-s[NÍ©
çêÈ©Á½D±Ìæ¤É Co/Eu2O3 G}Í CO2 Éηéea
«ªã-CCo/La2O3 G}Ìæ¤ÉY_–ð`¬µÈ©Á½±Æ
ªí©Á½D
Co/La2O3, Co/Eu2O3 G}ðp¢ÄMdʖ¦·MªÍ(TG–D-
TA)ðsÁ½‹Êð Fig. 8 ɦ·DTG–DTA ÌÀ±ÅÍG}ð
873 K ÅꢀfÒ³µ½ãC1 žÔECˆµÄ©çÀ±ðsÁ½D
Fig. 8 ÌòCòÍ
 ‚
CO
2 µÍC†º·©ç ÜŸ·µ½‹
1073 K
ƒ „
He
ÊÅCFig. 8 ÌòCòͺ·ÉßµÄ©ç µÍC†Åà¤ê
Fig. 7 Í FT–IR ̪è‹Êð¦·D}†òÍ Eu2O3, La2O3 ¨
æÑ Co2O3 Ìe_»¨É873 K Å CO2 ðzꢀ³¹C¯·xÅE
Cˆµ½ã̎¿ÌXyNg‹Å éDEu2O3 Æ Co2O3 ̎
¿ÌXyNg‹Í CO2 ˆOãɨ¢ÄÏ»ÍÈ©Á½ªCLa2
O3 Ìê‡C1467.6 cm|1, 1368.2 cm|1, 860.6 cm|1 Ézûs[N
ªÏ@³ê½D±êçÌs[NÍCLa2O3 \ÊãÉ`¬³ê½Y
x 1073 K ÜŸ·µÄªèðsÁ½‹ÊÅ éD
Fig. 8 ÌòCò©ç¼G}Æà-Ms[NÆdʝª©çê½D
Co/La2O3 G}ÅÍ»ÌdʝÍñiKÉÈÁÄ¢éD±êÍÒ
³³êĶ¬µ½à®Ro‹gãÅCCO2 Í Co{CO2¨CoO{
CO ̽žÉæÁĶ¬µ½_»Ro‹gÉæédÊÆ La2O3
{CO2¨La2O2CO3 ̽žÉæÁÄY_–̶¬Éæédʝð

‚

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2000
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Fig. 6 X–Ray diŠraction patterns of EuCoO3 and LaCoO3
catalysts.
LaCoO3 ò and EuCoO3 ò„ before reaction.
LaCoO3 ò‚ and EuCoO3 òꢀ reduced at 773 K by H2.
‚ and ꢀ used in the reaction at
(c, f): The catalysts of ò
ò
873 K.
¡: LaCoO3, £: La2O3, ~: La2O2CO3, : Film,
ž: EuCoO3, ¢: Eu2O3, œ: CoO, ›: Co.
Fig. 7 FT–IR spectra of ò CO2 adsorbed on the oxides, ò‚ LaCoO3 and òƒ EuCoO3.
@: Reduced at 773 K by H , A: @ treated with CO at 873 K,
ò
B: @ after the reaction of CH CO at 873 K.
ò ò
ò ò
2
2
{
4
2

ú»C2000, No. 9 àE³äE™RE¼cCgcFҳ؍uXJCg^¡_»¨G}Éæé^“Æñ_»YfÆ̽ž
619
Fig. 8 TG–DTA curves of the catalysts obtained by the reduction of Co/La2O3 and Co/Eu2O3.
(a, b) in CO2{He, (c, d) He ‰ow.
Temperature was raised with the rate of 10 K min|1
.
l¦çêéD
CO{H2O ̛½žªNÁÄ¢éÆl¦çêéDêûCè툫
ð¦³È©Á½ Pr, Nd æèÈé Co ðÜÞyuXJCg^G
}ÅÍCY_–𶬵ĢȢ±ÆªmF³êé±Æ©çC±
êçÌG}Í°ç-Ò³ªð³êÉ--Cà®Ro‹gðeÕÉ
¶¬µÈ¢½ßCˆ«ª-»µÈ¢Ì¾ë¤ÆvíêéD
693 K ÜÅ CO2 †Å¸·µ½ Co/La2O3 G}Ì XRD ªè‹Ê
ÅÍY_–(La2O2CO3 )̶¬ªmFÅ«½D±Ì±ÆæèCCo
/La2O3 G}ÌêiÚÌdʝÍà®Ro‹gª_»Ro‹gÉ
_»³êé±ÆÉæéàÌÆCñiÚÌdʝ͉“^“ÌY_
–̶¬ÉæéàÌÆl¦çêéD
D ‹
¾
³çÉ He µÍCºÅ¸··éÆ Co/La2O3 G}ÅÍ1003 K
ƒ
ÅzMs[NÆ»êɺ¤dʸª©çê½(Fig. 8ò)D±Ìd
LnCoO Ln La, Pr, Nd, Sm, E u, Gd, Dy, E r, Tb
(  )G}ðÒ³
3
ʸÍY_–̪ðÉæéàÌÆvíêéD
ªðµ½àÌðp¢Ä873 K ÌärIá·Å CH4{CO2¨2CO{
2H2 Co Eu O , Co Sm O Co
‚
êûCCo/Eu2O3 ÅÍ(Fig. 8ò)OÂÌ-Ms[Nª©çê½
½žðsÁ½‹Ê¨æÑ
/
/
3 ¨æÑ
2
/
2
3
ªCdʝÍêiK¾¯Å Á½DÀ±ã̎¿ðp¢Ä XRD
Æ FT–IR ̪èðsÁ½D»Ì‹ÊæèY_–̶¬ªFßç
êÈ©Á½Dܽ He µÍC†C¶¬µ½_»Ro‹gͳÌà
La2O3 G}ðÆè °ÄŸ¢ðsÁ½‹ÊðÜÆßéÆȺ̋
_ª¾çêéD
1) 773 K ÅꢀfÒ³µ½ãC873 K ɨ¯é½žˆ«Íeó
„
®ÉÒ³³êé±ÆªÅ«È¢ÌÅ Fig. 8òÅÍdÊÌϻͩ
Eu
©ç
yÞ³fÉæÁÄÙÈèC‰“^mChã¼O‹[vÌ
çêÈ©Á½D
Yb ÜÅÌe³fðÜÞ Co/Ln2O3 G}Ɉ«ª©çê½D
Èã̋ʩç CO2 ¾¯ÌµÍC†ÅÍÒ³ªðµÄ¶¬µ
½Ro‹gª_»³êÄ_»Ro‹gÉÈèCÁÉ Co/Eu2O3 Ì
ûª»ÌXüª-¢±Æªí©Á½Dµ©µC^“ª¤¶·é
Æ_»Ro‹gÍÄÑÒ³³êéÆvíêé(½žˆ«ª©çê
é±Æ©ç)DêûCCo/La2O3 G}Å͉“^“ÌY_–ð¶
¬µC»êª^“¤¶ºÅàeÕÉà®óÔÌRo‹gÖÌÒ
³ðjQµCG}ˆ«ªÈ©Á½Æl¦çêéD
2) ½žˆ«ªÙÈé Co/Eu2O3 Æ Co/Sm2O3 G}ÉεÄ
\ÊÁ«ÌŸ¢‹ÊCˆ«ª‚¢ Co/Eu2O3 G}Í\ÊÌ Co/
Ln ä¨æÑ_f̄‡ÍCCo/Sm2O3 G}Ì»êçæèá¢D
»Ì´öÍ EuCoO3 G}ÍÒ³³êâ·-CÒ³ªðãÌ Co/
Eu2O3 G}Ì\ÊÉà®Ro‹g̼ÉÒ³óÔÌ Eu ª¶Ýµ
Ä¢é±ÆÅ éDCo/Sm2O3 G}Í Co/Eu2O3 G}Æä×CÒ
³ªð³êÉ--CG}\ÊÉ_»óÔÌRo‹gª¶ÝµÄ¢
éD»Ì½ßCCo/Sm2O3 G}͈«ð¦³È¢D
EuCoO3, SmCoO3 ¨æÑ LaCoO3 ðÆè °½žˆ«Ì·Ù
ª¶¶é´öÉ¢IJ×Ä«½‹Êð‡·éÆCFig. 1Å
Eu æè´qԆÌå«¢óyÞ³fðÜÞyuXJCg^G
}ň«ð¦µ½±ÆÍ EuCoO3 Ìê‡Æ¯lÌÒ³ªð³ê
â·³ÉNö·éÆvíêéDµ©µCEuCoO3 ªðG}Ìê‡
ÆÙÈè CH4 æè CO2 Ì]»¦Ìûª‚¢D±êÍ CO2{H2¨
3) CO2 zꢀE£À±©ç Co/Eu2O3 G}Í838 K Å CO2 E
£_ª»êCCo/Sm2O3 G}ÅÍ©çêÈ¢D±êÍ Co/Eu2O3
G}Ìûª½ž«ª‚¢´öÆÈéD
4) Co/La2O3 G}ͽž¨¿Å éñ_»YfÉæèG}Ì
\Êɉ“^“ÌY_–𶬵C873 K ·xŪðªÅ«¸C

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½žðjQµÄ¢éD
Catal. Lett.,
7) Y. Wu, O. Kawaguchi, T. Matsuda, Bull. Chem. Soc. Jpn.,
71, 563 1998 .
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)
1) A. Slagtern, Y. Sc huurman, C. Lec lerc q, X. Verykios, C.
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9) †º™Cà‡rYCG}C35, 479(1993).
10) g@íªÍÌÄÑ«(3)hC»w¯lCŒž(1996), p. 166.
11) yd\êCÂ ÂõC¡RW¾C¡³ OCG}C40,
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13) ›ì œC¬Ñ³`Cú»C1996, 362.
14) L. H. Little ˜C·Jì³mÙ©óCgzꢀÆÔOüzûX
yNg‹hC»w¯l(1971), p. 49.
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Catalytic Reforming of Methane with Carbon Dioxide on Reduced
Perovskite–type Oxides
õ
õõ
Yunying WUÞ, Shoji MOTOI, Kazuo SUGIYAMA, Tsuneo MATSUDA and Yasuhiko YOSHIDA
Department of Applied Chemistry, Faculty of Engneering, Saitama University, 255 Simo–ohkubo,
Urawa–shi 338–8570 Japan
õPresent address: Research Center for Advanced Energy Conversion, Nagoya University, Furo–cho,
Chikusa–ku, Nagoya–shi 464–8603 Japan
õõDepartment of Applied Chemistry, Faculty of Engneering, Toyo University, 2100 Kuzirai,
Kawagoe–shi 350–8585 Japan
The reforming reactions of CH4 with CO2 diluted with He were carried out over the cobalt catalysts
prepared from the perovskite structural oxides, LnCoO3 (LnLa, Pr, Nd, Sm, Eu, Gd, Er, Tb) and the
relationship between the reaction activity and the surface properties of the catalysts were examined. The
reaction activity at 873 K of the catalysts containing the rear earth element of higher atomic number than
Eu was remarkably higher than that of the catalysts having lower atomic number than Eu.
The surfac e properties of the Co/La2O3, Co/Sm2O3 and Co/Eu2O3 catalysts decomposed from LaCoO3,
SmCoO3 and EuCoO3 were particularly examined. EuCoO3 was reduced much easier to metallic cobalt
and europium oxide than LaCoO3 and SmCoO3. The decomposed products by reduction were led to the
c atalyst with high ac tivity. On the other hand, LaCoOand SmCoO3 were not fully and easily reduced and
3
very small amount of cobalt oxides remained on the surface. The di‹culty of reducibility of LaCoO3 and
SmCoO3 caused the lost or low activity. The decomposed Co/Eu2O3 catalyst had two kinds of active sites
whic h operated at relatively low(873 K) and high temperature (1073 K) regions. The other two kinds of
catalysts had only one active site which operated at high temperature. This caused the lost or low activity
at low temerature such as 873 K in the case of the latter. Especially the decomposed Co/La2O3 catalyst
had a strong a‹nity to CO2 and easily produced a lanthanum carbonate which was decomposed at high
temperature („973 K). The formation of the carbonate inhibited the reaction, probably by the oxidation
of the metallic cobalt on the catalyst surface.
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