⺰ ᢥᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺߦࠃࠅ⺞⵾ߒߚ 2F<P1 ⸅ᇦߩࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰෻ᔕ․ᕈ
㩷࿪㊁ 㓷᢯‫᧻ޔ‬ේ ࿻૓‫ޔ‬੗਄ శᶈ‫ޔ‬㒙ㇱ ቁਯንጊᄢቇ᳓⚛ห૏૕⑼ቇ⎇ⓥ࠮ࡦ࠲࡯
‫ ޥ‬ንጊᏒ੖⑔ Methanol Steam Reforming Using Pd/ZnO Catalyst Prepared by the Polygonal
Barrel-Sputtering Method㩷Masato Danno, Keisuke Matsubara, Mitsuhiro Inoue, Takayuki Abe
Hydrogen isotope research center, University of Toyama
Gofuku 3190, Toyama 930-8555, Japan(Received December 13, 2011; accepted March 9, 2012)
Abstract
A Pd/ZnO sample prepared by the polygonal barrel-sputtering method was tested for the performance inmethanol steam reforming in comparison with a similar sample from a conventional wet process.
Transmission electron microscopy (TEM) showed that sputtering produced smaller and more uniformly
sized Pd nano-particles than the wet process. Steam reforming of methanol was conducted by supplying agaseous mixture of methanol + H2O + Ar. In the experiment with the polygonal barrel-sputtering method,
H2 generation started at a lower temperature (80 °C) than that for the wet process (100 °C). In addition,
H2O was scarcely consumed at both of the samples when H2 was generated at < 100 °C. These results
suggested that the sputtering preparation allowed direct decomposition of methanol to occur easily at lessthan 100 °C, as supported by the observed relationship between the CO/CO2 generation ratio and thereaction temperature. It should be noted that the smaller Pd particle sizes for the sputtering method weremaintained at reaction temperatures up to 150 °C.

1. ✜⸒ ᳓⚛ߪ‫ޔ‬࿾⃿᷷ᥦൻߩਥⷐ࿃ߣߐࠇࠆੑ㉄ൻ὇⚛㧔CO2㧕ߩឃ಴㊂೥ᷫߦ᦭ലߥࠛࡀ࡞ࠡ࡯Ḯߢ޽ࠆ‫⃻ޕ‬࿷‫ޔ‬᳓⚛ߪൻ⍹Άᢱࠍ᳓⫳᳇ᡷ⾰ߔࠆߎߣߢਥߦ⵾ㅧߐࠇߡ޿ࠆ‫ޔߜ߁ߩߎޕ‬᳓⫳᳇ᡷ⾰ߦᐢߊ↪޿ࠄࠇߡ޿ࠆࡔ࠲ࡁ࡯࡞ߪ⾂⬿߿ㆇ៝߇ኈᤃߢ޽ࠅ‫ޔ‬Ყセ⊛ૐࠛࡀ࡞ࠡ࡯ߢ᳓⚛ࠍขࠅ಴ߖࠆߣ޿߁೑ὐࠍ᦭ߔࠆ‫ޕ‬ ߎࠇ߹ߢ‫ޔ‬㊄ዻ㉄ൻ‛☳ᧃߦ Cu‫ޔ‬Pd ╬ߩ㊄ዻ࠽ࡁ☸ሶࠍᜂᜬߒߚ⸅ᇦߩࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰ᕈ⢻߇⹏ଔߐࠇߡ޿ࠆ[1-5]‫⸅ߩࠄࠇߎޕ‬ᇦߪ‫ߦ⊛⥸৻ޔ‬฽ᶐᴺߦઍ⴫ߐࠇࠆ࠙ࠚ࠶࠻ᴺߢ⺞⵾ߐࠇߡ޿ࠆ‫ߩߎޔߒ߆ߒޕ‬ᣇᴺߢߪ฽ᶐߐࠇߚ೨㚟૕ࠍടᾲಽ⸃ߔࠆ㓙‫☸ޔ‬ሶߩᚑ㐳߿ಝ㓸߇⿠
ߎࠆ[6]‫ߪࠇߎޕ‬෻ᔕࠨࠗ࠻ᢙߩᷫዋߦ❬߇ࠅ‫ޔ‬㕖ല₸ߥࡔ࠲ࡁ࡯࡞ᡷ⾰෻ᔕࠍ᜗ߊ‫ޕ‬ ਄⸥ߒߚ࠙ࠚ࠶࠻ᴺߩ໧㗴ࠍ⸃᳿ߔࠆߚ߼ߦߪ‫ޔ‬ടᾲᎿ⒟߇ਇⷐߥ⸅ᇦ⺞⵾ᴺ߇ᔅⷐߢ޽ࠆ‫ޕ‬ߘߎߢᚒ‫ޔߪޘ‬ንጊᄢቇ᳓⚛ห૏૕⑼ቇ⎇ⓥ࠮ࡦ࠲࡯ߢ㐿⊒ߐࠇߚ‫ޟ‬ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣ
ᴺ[7-12]‫ߦޠ‬ᵈ⋡ߒߚ‫ߩߎޕ‬ᣇᴺߪ‫ࠣࡦ࡝࠲࠶ࡄࠬޔ‬ᚻᴺࠍၮߦߒߚੇᑼߩᓸ☸ሶ⴫㕙ୃ㘼ᴺߢ޽ࠆ‫ޔ߼ߚߩߘޕ‬೨㚟૕ࠍ૶↪ߖߕ‫ޔ‬㊄ዻ࠽ࡁ☸ሶࠍᓸ☸ሶ⴫㕙ߦቶ᷷ߢᜂᜬߢ߈ࠆ‫ߩߎޕ‬೑ὐߦ઻޿‫ᧄޔ‬ᴺߢᜂᜬߐࠇߚ㊄ዻ࠽ࡁ☸ሶߩ☸ᓘߪᓸ⚦‫ޔ‬਌ߟဋ৻ߢ☸ሶߩಝ㓸߽⿠ߎࠄߥ޿[9-12]‫ޕ‬ߎࠇࠄߩ․ᕈߪ‫࡞࡯ࡁ࠲ࡔޔ‬᳓⫳᳇ᡷ⾰෻ᔕࠨࠗ࠻ᢙߩჇടߦ❬߇ࠆ‫ᦨߦࠄߐޕ‬ㄭ‫ޔ‬ᄙⷺࡃ࡟࡞
ࠬࡄ࠶࠲࡝ࡦࠣᴺߢ⺞⵾ߐࠇߚ⸅ᇦࠍ CO2 ߩࡔ࠲ࡦൻ෻ᔕߦ↪޿ࠆߣ‫ޔ‬෻ᔕ᷷ᐲ߇ 400͠߆ࠄ
160͠ߦૐਅߔࠆߎߣ߇ႎ๔ߐࠇߚ[11]‫․ߩߎޕ‬ᕈ߇ࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰෻ᔕߢ߽⊒⃻ߔࠇ߫‫ޔ‬⃻⁁ߩᡷ⾰᷷ᐲ㧔200͠એ਄[1-3]㧕ߩૐ᷷ൻ߽ᦼᓙߢ߈ࠆ‫ޕ‬ ߘߎߢ‫⎇ᧄޔ‬ⓥߢߪ‫ޔ‬ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺࠍ↪޿ߡࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰⸅ᇦߩ৻ߟ
ߢ޽ࠆ Pd ᜂᜬ ZnO ⸅ᇦ㧔Pd/ZnO㧕[1,3,4]ࠍ⺞⵾ߒ‫‛ߩߘޔ‬ᕈߣ⸅ᇦᕈ⢻ࠍᓥ᧪ᴺߣᲧセߒߚ‫ޕ‬
2. ታ㛎
2.1 ⹜ᢱߩ⺞⵾ Pd/ZnO ⹜ᢱߪ‫ޔ‬ZnO ☳ᧃ㧔ᐔဋ☸ᓘ 70 nm‫ࠢ࠶࠹ࠗࠬࠢࡂޔ‬㧕ࠍᜂ૕ߦ↪޿ߡ⺞⵾ߒߚ‫ޕ‬ZnO☳ᧃߪ᳓ಽߦࠃࠆ☸ሶߩಝ㓸ࠍ㒐ߋߚ߼ߦ‫↪૶ޔ‬೨ߦ 180͠ߢੇ῎ߒߚ[10,12]‫ޕ‬ᄙⷺࡃ࡟࡞ࠬࡄ࠶
࠲࡝ࡦࠣᴺߦࠃࠆ⹜ᢱߩ⺞⵾ߪ‫ޔ‬Pd ᧼㧔50 mm × 100 mm㧕ࠍ࠲࡯ࠥ࠶࠻ߦ↪޿ߡએਅߩࠃ߁ߦⴕ
ߞߚ[7-12]‫ޕ‬3.0 g ߩ ZnO ☳ᧃࠍዉ౉ߒߚ 8 ⷺࡃ࡟࡞ࠍ⌀ⓨ࠴ࡖࡦࡃ࡯ߦ⸳⟎ߒ‫ࡦࡐ࡯࡝࠲࡯ࡠޔ‬ࡊ‫ޔ‬ᴤ᜛ᢔࡐࡦࡊࠍ↪޿ߡ⌀ⓨឃ᳇ߒߚ‫ޕ‬࿶ജ߇ 8 × 10-4 Pa એਅߦ㆐ߒߚᓟ‫ޔ‬Ar ࠟࠬ㧔⚐ᐲ:99.999 %㧕ࠍ࠴ࡖࡦࡃ࡯ౝߦዉ౉ߒ‫ޔ‬RF ಴ജ: 100 W‫ޔ‬Ar ࠟࠬ࿶: 0.8 Pa‫ޔ‬ቶ᷷ߩ᧦ઙߢ 35 ಽ㑆ࠬࡄ࠶࠲࡝ࡦࠣࠍⴕߞߚ‫ޔᤨߩߎޕ‬ZnO ☳ᧃࠍዉ౉ߒߚ 8 ⷺࡃ࡟࡞ߪ‫ޔ‬ᝄ᏷: 75°‫ޔ‬๟ᦼ: 14.6 ⑽/࿁ߢᝄࠅሶേ૞ߐߖߚ‫ߩߎޕ‬ᠲ૞ߦࠃࠅ‫ޔ‬ZnO ☳ᧃߪᠣᜈߐࠇࠆߛߌߢߥߊ‫ޔ‬ੑᰴ☸ሶ߆ࠄ৻ᰴ☸
ሶ߳ߩ☳⎈߽⿠ߎࠆ‫ࠣࡦ࡝࠲࠶ࡄࠬޕ‬ᓟ‫ޔ‬N2 ࠟࠬ㧔⚐ᐲ: 99.99 %㧕ࠍ⌀ⓨ࠴ࡖࡦࡃ࡯ౝߦዉ౉ߒ‫ޔ‬ᄢ᳇࿶ߦᚯߒߡ߆ࠄ⹜ᢱࠍขࠅ಴ߒߚ‫⹜ߩߎޔ߅ߥޕ‬ᢱߩ Pd ᜂᜬ㊂ߪ‫ޔ‬ᓟߦㅀߴࠆ⺃ዉ⚿วࡊ࡜࠭ࡑේሶ⊒శಽᨆ㧔ICP-AES㧕ߦࠃࠅ 2.0 wt.%ߣ᳞߹ߞߚ‫ޕ‬એ㒠ߪ‫⹜ᧄޔ‬ᢱࠍ(BS)-Pd/ZnO ߣ⴫⸥ߔࠆ‫ޕ‬ (BS)-Pd/ZnO ⹜ᢱߣห╬ߩ Pd ᜂᜬ㊂ࠍ᦭ߔࠆෳᾖ⹜ᢱߪ฽ᶐᴺߢ⺞⵾ߒߚ[3]‫ߩߎޕ‬ᣇᴺߢߪ‫ޔ‬߹ߕ‫ޔ‬᳓ߦṁ߆ߒߚ 0.145 g ߩ Pd(NO3)2㧔㑐᧲ൻቇ㧕ࠍࠬࠢ࡝ࡘ࡯↉ౝߢ ZnO ☳ᧃߣᠣᜈߔࠆߎ

ߣߢဋ৻ߦᷙวߒߚ‫ޕ‬110͠ߢ৻᥅ੇ῎ᓟ‫⹜ޔ‬ᢱࠍ☳⎈ߒ‫ޔ‬ⓨ᳇ᵹㅢਅߦ߅޿ߡ 500͠‫ޔ‬3 ᤨ㑆ߩ᧦ઙߢ὾ᚑࠍⴕߞߚ‫ߩߎޕ‬὾ᚑ⹜ᢱࠍ෻ᔕ▤ߦలႯߒ‫ޔ‬400͠ߩ᷷ᐲߢ 1 ᤨ㑆᳓⚛ㆶరಣℂߒߚ‫ޕ‬ᓧࠄࠇߚෳᾖ⹜ᢱߩ Pd ᜂᜬ㊂ߪ 2.0 wt.%ߢ޽ߞߚ‫ޕ‬એ㒠ߪ‫ᧄޔ‬ෳᾖ⹜ᢱࠍ(IW)-Pd/ZnO ߣ⴫⸥ߔࠆ‫ޕ‬
2.2 ⺞⵾⹜ᢱߩ‛ᕈ⹏ଔ ⺞⵾⹜ᢱߩ Pd ᜂᜬ㊂ߪ⹜ᢱਛߩ Pd ࠍỚ⎣㉄ߦṁ⸃ߒ‫ߩߘޔ‬Ꮧ㉼ṁᶧࠍ ICP-AES㧔Optima7300DV‫ޔ‬PerkinElmer㧕ߢಽᨆߔࠆߎߣߢ᳞߼ߚ‫⹜⵾⺞ޕ‬ᢱߩᓸⷞ⊛ߥ‛ᕈߪ‫ޔ‬ㅘㆊ㔚ሶ㗼ᓸ㏜
㧔TEM: JEM-2100‫ޔ‬JEOL㧕ࠍ↪޿ߡ⹏ଔߒߚ‫ޕ‬
TEM ᷹ቯߪ㜞࿶㔚Ḯ㔚࿶ࠍ 200 kV ߦ⸳ቯߒ‫ޔ‬300,000୚ߩ୚₸ߢⴕߞߚ‫ޔ߅ߥޕ‬Pd ☸ሶߩ☸ᓘಽᏓߪ‫ޔ‬TEM ௝߆ࠄછᗧߦㆬ೎ߒߚ 100 ୘એ਄ߩ☸ሶߩ☸ᓘࠍ⷗Ⓧ߽ࠆߎߣߢ૞ᚑߒߚ‫ޕ‬
2.3 ࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰ᕈ⢻⹏ଔ ࡔ࠲ࡁ࡯࡞᳓⫳᳇෻ᔕߪ‫⵾ࠬ࡟ࡦ࠹ࠬޔ‬෻ᔕ▤㧔ౝᓘ: 4.35 mm㧕ࠍ↪޿ߡᏱ࿶࿕ቯᐥᵹㅢᑼߢએਅߩࠃ߁ߦⴕߞߚ[3]‫♽ޔߕ߹ޕ‬ౝߩᱷ⇐‛ࠍ㒰ߊߚ߼ߦ‫ ߡ޿↪ࠍ࡯࠲࡯ࡅࡦࡏ࡝ޔ‬0.4 g ߩ
Pd/ZnO ⹜ᢱࠍలႯߒߚ෻ᔕ▤ࠍ Ar ࠟࠬࠍᵹߒߥ߇ࠄ 80͠߹ߢടᾲߒߚ‫ޔߡ޿⛯ޕ‬Ar ࠟࠬࠍࡔ࠲ࡁ࡯࡞ߣ᳓ߩࡃࡉ࡜࡯ߦㅢ᳇ߒ‫࡞࡯ࡁ࠲ࡔޔ‬᳓⫳᳇ᡷ⾰෻ᔕࠍⴕߞߚ㧔ࠟࠬᵹ㊂Ყ CH3OH:H2O:Ar= 8.4:12:30 ml/min㧕‫ޔᤨߩߎޕ‬෻ᔕ▤એᄖߩࠟࠬᵹ〝ߪ࡝ࡏࡦࡅ࡯࠲࡯ࠍᏎ޿ߡ 120͠ߦ଻᷷ߒߚ‫ޕ‬30 ಽᓟ‫ޔ‬෻ᔕ↢ᚑ‛ࠍ TCD ࠟࠬࠢࡠࡑ࠻ࠣ࡜ࡈ㧔GC-8A‫ޔ‬ፉᵤ⵾૞ᚲ㧕ߢಽᨆߒߚ‫ߩߎޕ‬ಽᨆߢߪ‫ޔ‬H2࡮CO2࡮CO ಽᨆ↪ߦ Activated carbon㧔ౝᓘ: 3 mm‫ޔ‬㐳ߐ: 2 m‫ޔ‬ፉᵤ⵾૞ᚲ㧕‫ޔ‬CH3OH࡮H2O ↪ߦ GaskuroPack 54㧔ౝᓘ: 3 mm‫ޔ‬㐳ߐ: 3 m‫ޔ‬ፉᵤ⵾૞ᚲ㧕ࠍࠞ࡜ࡓߣߒߡ૶↪ߒ‫ࡓ࡜ࠞޔ‬᷷ᐲߣᬌ಴ེ᷷ᐲߪ‫ ࠇߙࠇߘޔ‬150͠‫ޔ‬170͠ߦ⸳ቯߒߚ‫ ߚ޿↪ߦࠬࠟࠕ࡝ࡖࠠޔߚ߹ޕ‬Ar ࠟࠬߪ 50 ml/min ߢᵹㅢߒߚ‫ޔ߅ߥޕ‬਄

(II)
㩷(A)

60

ߟ਄ߍ‫࡞࡯ࡁ࠲ࡔޔ‬ォൻ₸߇ 100%40

ߦ㆐ߔࠆ߹ߢⴕߞߚ‫ޕ‬
20 nm2003. ⚿ᨐ(B) ⺞⵾ߒߚ Pd/ZnO ⹜ᢱߩᓸⷞ⊛‛ᕈࠍ⹏ଔߔࠆߚ߼ߦ‫ޔ‬TEM ᷹ቯࠍⴕߞߚ‫ޕ‬࿑ 1(I)ߪ‫(ޔ‬A) (BS)-Pd/ZnO‫ޔ‬(B) (IW)-Pd/ZnO ߩౖဳ⊛ߥ TEM ௝ࠍ␜ߔ‫⹜ߩࠇߕ޿ޕ‬ᢱߦ߽Ἧ⦡ߢ⴫
ߐࠇࠆ ZnO ᜂ૕਄ߦ Pd ࠽ࡁ☸ሶ߇⹺߼ࠄࠇࠆ‫ޔߒ߆ߒޕ‬࿑ 1(II)ߦ␜ߔ

080

20 nm

Distribution / %3.1 Pd/ZnO ߩ‛ᕈ⹏ଔn = 202(Average size: 2.4 nm)

8051015Diameter/ nm
㩷20n = 100(Average size: 3.8 nm)

6040㩷↢ᚑ‛ಽᨆߪ‫ޔ‬෻ᔕ▤᷷ᐲࠍ 20͠ߕ(I)
Distribution / %⸥ߒߚࡔ࠲ࡁ࡯࡞᳓⫳᳇෻ᔕߣ෻ᔕ

200051015Diameter / nm

20

Figure 1 (I) Typical TEM images and (II) particle size
distribution of (A) (BS)-Pd/ZnO and (B) (IW)-Pd/ZnO ([n]:number of particle counts).

Pd ߩ☸ᓘಽᏓࠍ⷗ࠆߣ‫(ޔ‬BS)-Pd/ZnO ߩ☸ሶߪ⚂ 1㨪6 nm ߦಽᏓߒߡ޿ࠆߩߦኻߒ‫(ޔ‬IW)-Pd/ZnOߩಽᏓߪ⚂ 1㨪12 nm ߣ᏷ᐢ޿‫(ޔߚ߹ޕ‬BS)-Pd/ZnO ߩᐔဋ☸ᓘߪ 2.4 nm ߢ޽ࠅ‫(ޔ‬IW)-Pd/ZnO㧔3.8nm㧕ߩ⚂ 2/3 ୚ߢ޽ࠆ‫⚿ߩࠄࠇߎޕ‬ᨐ߆ࠄ‫ޔ‬ቶ᷷ߢ⺞⵾น⢻ߥᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺߪ‫ޔ‬ဋ৻‫ޔ‬਌ߟᓸ⚦ߥ Pd ࠽ࡁ☸ሶࠍ㜞ಽᢔᜂᜬߢ߈ࠆᚻᴺߢ޽ࠆߎߣ߇ࠊ߆ࠆ‫ޕ‬
3.2 ࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰෻ᔕ ࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰ߪਥߦ(1)ᑼߦᓥߞߡ⿠ߎࠆ[2-5]‫⋥࡞࡯ࡁ࠲ࡔޔߚ߹ޕ‬ធಽ⸃෻ᔕ(2)߇⿠
ߎࠅ‫ޔ‬᷷ᐲߩ਄᣹ߦ઻ߞߡ(3)ᑼ߇ᓟ⛯ߔࠆ෻ᔕ⚻〝߽ႎ๔ߐࠇߡ޿ࠆ[3]‫ޕ‬
CH3OH + H2O → 3H2 + CO2(1)CH3OH → 2H2 + CO(2)CO + H2O → H2 + CO2(3)ߎࠇࠄߩ෻ᔕᑼࠍၮߦ‫ޔ‬CH3OH ォ឵₸ࠍࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰෻ᔕߢᓧࠄࠇߚࠟࠬࠢࡠࡑ࠻ࠣ࡜
ࡈ࠺࡯࠲ߣ(4)ᑼ߆ࠄ᳞߼ߚ‫ޕ‬
CH3OH ォ឵₸ (%) = (CH3OH ᶖ⾌ࡕ࡞ᢙ)/( CH3OH ଏ⛎ࡕ࡞ᢙ) × 100(4)ᓧࠄࠇߚ CH3OH ߩォ឵₸ߣ෻ᔕ᷷ᐲߩ㑐ଥࠍ࿑ 2(A)ߦ␜ߔ‫ߩߎޕ‬࿑ߦ␜ߔ CH3OH ォൻ₸ߪ‫޿ޔ‬ߕࠇߩ᷷ᐲߦ߅޿ߡ߽(BS)-Pd/ZnO ߩᣇ߇ᄢ߈޿‫(ޔߚ߹ޕ‬BS)-Pd/ZnO ߦ߅޿ߡォൻ₸߇ 100%ߦ೔㆐ߔࠆ᷷ᐲߪ 260͠ߢ޽ࠅ‫(ޔ‬IW)-Pd/ZnO ߢᓧࠄࠇߚ 280͠ࠃࠅ 20͠ૐ޿‫ޕ‬ ৻ᣇ‫ޔ‬෻ᔕᑼ(1)‫(߮ࠃ߅ޔ‬2)+(3)ߩ⚻〝ߢߪ‫ ߽ࠇߕ޿ޔ‬1 mol ߩࡔ࠲ࡁ࡯࡞ߣ 1 mol ߩ H2O ߆ࠄ
3 mol ߩ H2 ߇↢ߓࠆ‫ޔࠄ߆ߣߎߩߎޕ‬H2 ෼₸ߣ H2O ߩᶖ⾌₸ߪᑼ(5)‫(ޔ‬6)ࠃࠅ᳞߼ࠆߎߣ߇ߢ߈
ࠆ‫ޕ‬
H2 ෼₸ (%) = (H2 ↢ᚑࡕ࡞ᢙ)/(CH3OH ଏ⛎ࡕ࡞ᢙ) × 1/3 × 100(5)

H2O ᶖ⾌₸ (%) = (H2O ᶖ⾌ࡕ࡞ᢙ)/(H2O ଏ⛎ࡕ࡞ᢙ) × 100(6)(5)ᑼ߆ࠄᓧࠄࠇߚ H2 ෼₸ߣ෻ᔕ᷷ᐲߩ㑐ଥࠍ࿑ 2(B)ߦ␜ߔ‫ߩߎޕ‬࿑ߦ߅޿ߡ‫ޔ‬200͠એ਄ߩ᷷ᐲ
㗔ၞߩ H2 ෼₸ߪ(IW)-Pd/ZnO ߩᣇ߇㜞޿‫(ޔᤨߩߎޕ‬6)ᑼ߆ࠄ H2O ᶖ⾌₸ࠍ᳞߼ࠆߣ‫ޔ‬࿑ 2(C)ߦ
␜ߔࠃ߁ߦ‫ࠅࠃޔ‬ᄙߊߩ᳓߇(IW)-Pd/ZnO ਄ߢᶖ⾌ߐࠇࠆ‫⚿ߩࠄࠇߎޕ‬ᨐߪ‫ޔ‬200͠એ਄ߩ᷷ᐲ㗔ၞߦ߅޿ߡ‫ޔ‬෻ᔕ(1)‫(ߪ޿ࠆ޽ޔ‬3)߇(IW)-Pd/ZnO ਄ߢ⿠ߎࠅᤃ޿ߎߣࠍ␜ߔ‫ޕ‬ ৻ᣇ‫ޔ‬100͠એਅߩ㗔ၞࠍ᜛ᄢߔࠆߣ‫( ޔ‬BS)-Pd/ZnO ߢߪ 80͠߆ࠄ᳓⚛߇↢ᚑߔࠆߩߦኻߒ‫ޔ‬(IW)-Pd/ZnO ߢߪ 100͠߹ߢ᳓⚛ߪ↢ᚑߒߥ޿㧔࿑ 2(B)ᝌ౉࿑ෳᾖ㧕‫ߩߎޔߚ߹ޕ‬᷷ᐲ㗔ၞߩ᳓⚛
↢ᚑ㊂ߪ(BS)-Pd/ZnO ߩᣇ߇ᄙ޿‫ޔߦࠄߐޕ‬࿑ 2(C)ࠍ⷗ࠆߣ‫⹜ߩࠇߕ޿ޔ‬ᢱߦ߅޿ߡ߽ 100͠એਅߢ H2O ߪ߶ߣࠎߤᶖ⾌ߐࠇߥ޿‫⚿ߩࠄࠇߎޕ‬ᨐ߆ࠄ‫ޔ‬100͠એਅߢߪ෻ᔕᑼ(2)ߦ␜ߔࡔ࠲ࡁ࡯࡞
ߩ⋥ធಽ⸃߇⿠ߎࠆߣ⠨߃ࠄࠇ‫ߩߎޔ‬෻ᔕߪ (BS)-Pd/ZnO ਄ߢ⿠ߎࠅᤃ޿ߣផ᷹ߐࠇࠆ‫ޕ‬㩷

100(A)(IW)-Pd/ZnO

4020(IW)-Pd/ZnO

050

100150200
250
Reaction temperature / °C

300

40050(IW)-Pd/ZnO

0.020.0020(BS)-Pd/ZnO

6080
100
Reaction temperature / °C(BS)-Pd/ZnO

100150200250300

Temperature / °C

㩷50600.04㩷

60

H2 yield / %(BS)-Pd/ZnO(C)40(IW)-Pd/ZnO30

㩷

H2O consumption ratio / %(B)8080
㩷
H2 yield/%

CH3OH conversion ratio / %100

2010050Figure 2 (A) CH3OH conversion ratio, (B) H2yield, and (C) H2O consumption ratio formethanol steam reforming reaction on Pd/ZnO
catalysts as a function of reaction temperature.
The inset in (B) shows the magnified graph atless than 100 °C.

(BS)-Pd/ZnO

100

150

200

250

300

Reaction temperature / °C
 CO‫ ߮ࠃ߅ޔ‬CO2 ↢ᚑ₸ߪ‫ޔ‬෻ᔕᑼ(1)㧙(3)ߦၮߠ߈એਅߩᑼ߆ࠄ᳞߼ߚ‫ޕ‬CO ↢ᚑ₸ (%) = (CO ↢ᚑࡕ࡞ᢙ)/(CH3OH ଏ⛎ࡕ࡞ᢙ) × 100(7)

CO2 ↢ᚑ₸ (%) = (CO2 ↢ᚑࡕ࡞ᢙ)/(CH3OH ଏ⛎ࡕ࡞ᢙ) × 100(8)࿑ 3(A)ߪ(IW)-Pd/ZnO ߩ CO‫ ߮ࠃ߅ޔ‬CO2 ߩ↢ᚑ₸ߣ෻ᔕ᷷ᐲߩ㑐ଥࠍ␜ߔ‫ߩߎޕ‬࿑ߦ߅޿ߡ‫ޔ‬CO ߪ 140͠߆ࠄ↢ᚑߒᆎ߼ࠆ‫ߩߎޕ‬᷷ᐲߪ࿑ 2(B)ߦ␜ߔ H2 ↢ᚑ㐿ᆎ᷷ᐲߦㄭߊ‫(ޔ‬2)ᑼߩࡔ࠲ࡁ
࡯࡞ߩ⋥ធಽ⸃߇⿠ߎߞߡ޿ࠆߎߣࠍᡰᜬߔࠆ‫ޔߚ߹ޕ‬࿑ 3(A)ߢߪ‫ޔ‬CO ↢ᚑ₸߇ 180͠߆ࠄૐਅ
ߔࠆߩߦ઻޿‫ޔ‬CO2 ߇ 160͠߆ࠄ↢ᚑߔࠆ‫⚿ߩࠄࠇߎޕ‬ᨐ߆ࠄ‫ޔ‬180͠એ਄ߢߪ(1)ᑼ‫(߮ࠃ߅ޔ‬3)
ᑼ߇ᡰ㈩⊛ߦ⿠ߎࠆߣ⠨߃ࠄࠇࠆ‫ޕ‬ (BS)-Pd/ZnO ߢᓧࠄࠇߚ⚿ᨐߪ࿑ 3(B)ߦ␜ߔ߇‫ޔ‬CO ↢ᚑ₸ߣ᷷ᐲߩ㑐ଥߪ࿑ 3(A)ߦ㘃ૃߔࠆ‫ޕ‬ߒ߆ߒ‫(ޔ‬BS)-Pd/ZnO ߢᓧࠄࠇࠆ CO ↢ᚑ₸ߪ(IW)-Pd/ZnO ࠃࠅ᣿ࠄ߆ߦᄢ߈޿‫ߩߎޔߚ߹ޕ‬࿑ߦ߅޿ߡ‫ޔ‬CO2 ↢ᚑ₸ߪ 200͠߹ߢჇടߒߥ޿‫⚿ߩࠄࠇߎޕ‬ᨐ߆ࠄ‫ޔ‬200͠ࠃࠅૐ޿᷷ᐲ㗔ၞߢ↢ᚑߔࠆ᳓⚛ߪਥߦ(2)ᑼߩࡔ࠲ࡁ࡯࡞ߩ⋥ធಽ⸃ߦ↱᧪ߔࠆߣ⸒߃‫(ޔ‬2)ᑼ߇(BS)-Pd/ZnO ਄ߢ⿠ߎࠅᤃ޿ߣ޿߁࿑ 2 ߩ⚿ᨐߦ╓วߔࠆ‫ޔ߅ߥޕ‬200͠એ਄ߢߪ‫(ޔ‬IW)-Pd/ZnO ߣห᭽ߦ‫ޔ‬CO ↢ᚑ₸ߩᷫዋߦ઻޿ CO2 ↢ᚑ₸߇Ⴧടߔࠆ‫⚿ߩߎޕ‬ᨐ߆ࠄ‫(ޔ‬BS)-Pd/ZnO ߦ߅޿ߡ(1)‫(ߪ޿ࠆ޽ޔ‬3)ᑼ߇ᡰ

㈩⊛ߦ⿠ߎࠅᆎ߼ࠆ᷷ᐲߪ(IW)-Pd/ZnO ࠃࠅ 20͠㜞޿ߎߣ߇ࠊ߆ࠆ‫ޕ‬
㩷

80

80

6060

40402020050100 150 200 250
Reaction temperature / °C

0300

100100(B) (BS)-Pd/ZnO

808060604040

2020050100

150200250

0300

Reaction temperature / °C

Figure 3 CO and CO2 generation ratios for methanol steam reforming reaction on Pd/ZnO catalysts as afunction of reaction temperature.
 ߐࠄߦ‫ޔ‬෻ᔕᓟߩ⹜ᢱਛߩ Pd ☸ሶߩᐔဋ☸ᓘࠍ TEM ᷹ቯߢ⷗Ⓧ߽ߞߚ㧔⴫ 1㧕‫⚿ߩߘޕ‬ᨐ‫ޔ‬(IW)-Pd/ZnO ⹜ᢱߪ 280͠ߩ෻ᔕᓟ‫ޔ‬ᐔဋ☸ᓘߪᄢ߈ߊᄌൻߒߡ޿ߥ߆ߞߚ‫ߦࠇߎޕ‬ኻߒ‫ޔ‬(BS)-Pd/ZnO ߦ㑐ߒߡߪ‫ޔ‬200͠ߢᐔဋ☸ᓘߩჇട߇⹺߼ࠄࠇߚ߽ߩߩ‫ࠇߘޔ‬એਅߩ᷷ᐲߩᐔဋ☸
ᓘߪ෻ᔕ೨ߣห╬ߢ޽ߞߚ‫ޕ‬
Table 1 Relationship between methanol steam reforming temperatures and averagesizes of Pd particles in Pd/ZnO catalysts.
SampleReaction temperature / °C
Average Pd particle size1) / nm(IW)-Pd/ZnO
Before3.8280
4.4(BS)-Pd/ZnO
Before2.4
150
2.32003.21) These data were estimated by averaging the sizes of more than 100 randomly
chosen particles from TEM images.
 ߎߎߢ‫ޔ‬TEM ᷹ቯ⚿ᨐࠍၮߦ‫ޔ‬H2 ↢ᚑ᜼േߦ෸߷ߔ⴫㕙Ⓧߩᓇ㗀ࠍᬌ⸛ߒߚ‫ޕ‬Pd ㊄ዻ࠽ࡁ☸
ሶࠍ⃿૕ߣ઒ቯߔࠆߣ‫ޔ‬Pd ☸ሶߩᲧ⴫㕙Ⓧ㧔S: m2/g㧕ߪએਅߩᑼ߆ࠄ᳞߼ࠆߎߣ߇ߢ߈ࠆ[13-15]‫ޕ‬S = 6000/ρd(9)ߎߎߢ‫ޔ‬ρ ߪ Pd ߩኒᐲ㧔g/cm3㧕‫ޔ‬d ߪᐔဋ☸ᓘ㧔nm㧕ࠍ⴫ߔ‫ߩߎޕ‬ᑼߣ TEM ᷹ቯ߆ࠄᓧࠄࠇߚPd ߩᐔဋ☸ᓘ‫߮ࠃ߅ޔ‬෻ᔕߦ૶↪ߒߚ⹜ᢱਛߩ Pd ㊂߆ࠄ Pd ߩ⴫㕙Ⓧࠍ᳞߼‫ޔ‬࿑ 2 ߩ H2 ෼₸ߩࠣ࡜ࡈࠍⷙᩰൻߒߚ‫ޔߒ߆ߒޕ‬ਔ⹜ᢱߩ⚿ᨐߪ৻⥌ߒߥ߆ߞߚ‫ޔߪࠇߎޕ‬H2 ↢ᚑ᜼േߦኻߒ‫⴫ޔ‬CO2 generation ratio / %100

CO generation ratio / %(A) (IW)-Pd/ZnO

㩷CO2 generation ratio / %CO generation ratio / %100㕙Ⓧߣߪ⇣ߥࠆⷐ࿃߇ᓇ㗀ߔࠆߎߣࠍ⴫ߔ‫ޕ‬వߦㅀߴߚࠃ߁ߦ‫ޔ‬ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺߢᜂᜬߐࠇߚ Pd ࠽ࡁ☸ሶߪᓸ⚦ߢဋ৻ߥ☸ᓘࠍ᦭ߒ‫ޔ‬ߎߩ☸ᓘߪ 150͠ߩ෻ᔕ᷷ᐲ߹ߢ⛽ᜬߐࠇࠆ‫ޕ‬ߎࠇࠄߩ⚿ᨐ߆ࠄ‫ޔ‬Pd ߩᓸ⚦ߥ☸ᓘ߇ 150͠એਅߩ H2 ↢ᚑ᜼േߦ㑐ਈߔࠆߣផ᷹ߐࠇࠆ‫ߎߩߎޕ‬ߣࠍ᣿ࠄ߆ߦߔࠆߚ߼ߦߪ‫ࠆߥࠄߐޔ‬ᬌ⸛߇ᔅⷐߢ޽ࠆ‫ޕ‬
4. ߹ߣ߼ ᧄ⎇ⓥߢߪ‫ޔ‬ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺߢ⺞⵾ߒߚ Pd/ZnO ⸅ᇦߩࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰․ᕈ
ࠍᓥ᧪ᴺߢ⺞⵾ߒߚ⹜ᢱߣᲧセߒߚ‫ޕ‬ᓧࠄࠇߚ⚿ᨐࠍએਅߦ߹ߣ߼ࠆ‫ޕ‬
㧔1㧕⺞⵾⹜ᢱߩ TEM ᷹ቯ⚿ᨐ߆ࠄ‫ ߚࠇߐࠣࡦ࡝࠲࠶ࡄࠬޔ‬Pd ߪ ZnO ᜂ૕਄ߢ࠽ࡁ☸ሶࠍᒻᚑߒ‫☸ޔ‬ᓘߪᓥ᧪ᴺ⹜ᢱࠃࠅᓸ⚦ߢဋ৻ߢ޽ࠆߎߣ߇ࠊ߆ߞߚ‫ޕ‬
㧔2㧕ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣᴺߢ⺞⵾ߒߚ⹜ᢱߩࡔ࠲ࡁ࡯࡞᳓⫳᳇ᡷ⾰ߢߪ H2 ߇ 80͠߆ࠄ↢ᚑߒ‫ޔ‬100͠એਅߩ H2 ↢ᚑ㊂ߪ฽ᶐᴺ⺞⵾⹜ᢱࠃࠅᄙ߆ߞߚ‫ޔߚ߹ޕ‬100͠એਅߢߪ H2O ߪ߶ߣࠎߤᶖ⾌ߐࠇߥ߆ߞߚ‫⚿ߩࠄࠇߎޕ‬ᨐ߆ࠄ‫ޔ‬ૐ᷷㗔ၞߢ⿠ߎࠆࡔ࠲ࡁ࡯࡞ߩ⋥ធಽ⸃෻ᔕߪᄙⷺ
ࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣ⺞⵾⹜ᢱߢ⿠ߎࠅᤃ޿ߣ⠨߃ࠄࠇࠆ‫ޕ‬
㧔3㧕CO‫ ߮ࠃ߅ޔ‬CO2 ↢ᚑ₸ߣ᷷ᐲߩ㑐ଥߪ‫ޔ‬਄⸥ߒߚૐ᷷㗔ၞߢࡔ࠲ࡁ࡯࡞ߩ⋥ធಽ⸃෻ᔕ߇
⿠ߎࠅᤃ޿ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣ⺞⵾⹜ᢱߩ․ᕈߣ╓วߔࠆ‫ޕ‬
㧔4㧕ᄙⷺࡃ࡟࡞ࠬࡄ࠶࠲࡝ࡦࠣ⺞⵾⹜ᢱߦ߅޿ߡ‫ޔ‬Pd ߩᓸ⚦ߥ☸ᓘߪ 150͠ߩ෻ᔕ᷷ᐲ߹ߢ⛽ᜬߐࠇߚ‫ޕ‬
Reference(1) Y.-H. Chin, R. Dagle, J. Hu, A.C. Dohnalkova and Y. Wang, Catal. Today, 77 (2002) 79.
(2) T. Shishido, Y. Yamamoto, H. Morioka, K. Takaki and K. Takehira, Appl. Catal. A: Gen., 263 (2004)
249.
(3) Y. Suwa, S. Ito, S. Kameoka, K. Tomishige and K. Kunimori, Appl. Catal. A: Gen., 267 (2004) 9.
(4) S. Sá, H. Silva, L. Brandão, J.M. Sousa and A. Mendes, Appl. Catal. B: Environ., 99 (2010) 43.
(5) T.-J. Huang and H.-M. Chen, Int. J. Hydrogen Energy, 35 (2010) 6218.
(6) T. Kawaguchi, W. Sugimoto, Y. Murakami and Y. Takasu, J. Catal., 229 (2005) 176.
(7) T. Abe, S. Akamaru, K. Watanabe and Y. Honda, J. Alloys Compd., 402 (2005) 227.
(8) S. Akamaru, S. Higashide, M. Hara and T. Abe, Thin Solid Films 513 (2006) 103.
(9) H. Yamamoto, K Hirakawa and T. Abe, Mater. Lett., 62 (2008) 2118.
(10) M. Inoue, H. Shingen, T. Kitami, S. Akamaru, A. Taguchi, Y. Kawamoto, A. Tada, K. Ohtawa, K.
Ohba, M. Matsuyama, K. Watanabe, I. Tsubone, and T. Abe, J. Phys. Chem. C, 112 (2008) 1479.
(11) T. Abe, M. Tanizawa, K. Watanabe and A. Taguchi, Energy Environ. Sci., 2 (2009) 315.
(12) K. Hirakawa, M. Inoue and T. Abe, Electrochim. Acta, 55 (2010) 5874.
(13) D. Chu and S. Gilman, J. Electrochem. Soc., 143 (1996) 1685.
(14) Z.B. Wang, G.P. Yin and P.F. Shi, J. Alloys Compd., 420 (2006) 126.

(15) T. Vidaković, M. Christov and K. Sundmacher, Electrochim. Acta, 52 (2007) 5606.