奈米科技在綠色能源的應用

(1)

奈米科技

在綠色能源的應用

陳郁文

(2)

2

“In the beginning of a change, the patriot is a

scarce man, and brave and hated and scorned.

When his cause succeeds, the timid join him,

for then it cost nothing to be a patriot.”

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

Sunlight Green plant E n e rg y H₂O, CO₂ Chemical energy C₆H₁₂O₆, O₂ Photocatalyst H₂O, CO₂ CH₃OH, O₂ Chemical energy 703 kJ/mol (1.21eV) Sunlight E n e rg y

Artificial chlorophyll

Photosynthetic efficiency: 5-6%

(24)

TEM: TiO

₂

Prepared at 90℃ for 16 h

(25)

92 短程 95 中程 99 長程 103(年) 時程技術層次控制金屬觸媒之粒徑提高活性與壽命,放大測試反應因子之控制制程整合設計量產

(26)

Gold catalyst has exceptionally high

low-temperature CO oxidation activity

Goodman et al., Science 281 (1998) 1647 350K 4.0 3.0 2.0 1.0 2.0 3.0 4.0 5.0 6.0 1.2 0.8 0.4 0 TOF ( 1/ si te •s )

Average cluster diameter (nm)

Ban d G ap M eas ure d by S TS (e V) TiO₂ 12 atoms 2 or 3 atoms

(27)

TEM images of Au/TiO

₂

prepared by NH

₄

OH

at pH6

Au particle size (nm) 0 1 2 3 4 5 6 7 Dis tributi on (%) 0 10 20 30 40 50 60 Fresh (D_avg = 2.45 nm) After reaction (D_avg=3.04 nm)

(c) Fresh During reaction Au (1 1 1) D_sp = 0.24 nm TiO₂ (1 0 1) D_sp = 0.36 nm

The average particle size of gold increase

from 2.5 to 3 nm during reaction.

5 nm HRTEM

(28)

fuel processors

• POX • SRM • SROM • CO<1 % • Ambient-100℃ • Au, Pt • CO< 10 ppm Choudhary and Goodman, Catal. Today 77 (2002) 65.

HTS LTS Sulfur-free CH₄ H₂O Reformer Water-gas shift rxns. 10% CO 3%CO 0.5%CO PROX 5-10ppm PEM CO + H₂O  CO₂+ H₂

HTS: High temperature shift; LTS: Low temperature shift; PROX preferential oxidation; PEM: Fuel

(29)

VOC + air CO2 + H2O

陶瓷纖維紙觸媒轉輪

(30)

50 100 150 200 250 300 350 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 Ben z e n e C o n v e rsi o n (% ) Temperature(OC) 1% Au/CeO 2(c300) 1% Au/2% V 2O5/CeO2(c300) 1% Pt/2% V 2O5/CeO2(c300) 1% Pt/CeO 2-DP(c350->reduction) 1% Pt/CeO 2-DP(c350) 1% Pt/Al 2O3-DP(c350->reduction) 1% Pt/Al 2O3-DP(c350) 1wt.%Au/CeO₂於300 ℃下鍛燒即有很好的活性，添加釩氧化物更可促進反應進行，且不需經過氫氣還原的步驟，較1wt.%Pt/suppor 活性佳

(31)

NiB is a core-shell structure. The

core is elemental Nickel and

the shell is amorphous Boron

species.

(Geng et al., Chem. Comm, 969,

2007)

(32)

Reaction conditions: T = 80℃, P = 930 kPa (120 psig), Citral/Cyclohexane/Ni = 10 ml/ 70 ml/ 2 mmol.

NiB/SiO₂(>10) > ME-NiB(5.1) > PVP-NiB(3.6)>NiB(1)

Hydrogenation of citral

Catalyst

Time Conv. Selectivity (%)

(min) (%) CAL COL 3,7-ol Other

s NiB 30 19.5 94.8 2.2 1.8 1.2 60 38.6 94.1 3.1 1.9 0.9 PVP-NiB 30 70.7 95.8 1.9 0.0 2.3 60 90.3 92.6 5.7 0.0 1.7 ME-NiB 30 98.7 76.7 19.7 0.0 3.6 60 100.0 62.2 33.5 1.8 2.5 NiB/SiO₂ (0.7 mmol) 30 99.7 57.4 32.3 6.3 4.0 60 100.0 26.4 38.5 25.0 10.1 O _O Citral (cis+trans) 檸檬醛香茅醛 H2 Citronellal (CAL) C=C

(33)

(34)

(35)

35

奈米金屬改質光觸媒於水中污染物及揮發性

(36)

36

(37)

Water To get energy Pump Excitation e -Electric power h+ Valence band (Pool of e-) Chemical reaction Light Photocatalyst Pumping CB

(38)

38

h

u

e -h+ D D+ A A -A: Acceptor D: Pollutants • 廢水中的有機物 • VOCs CB VB e -e -e -h+ h+ h+

光催化降解污染物的應用

(39)

(40)

40 光觸媒在水處理過程中可產生羥基自由基，使水體中的大分子有機物氧化降解成低毒或無毒的小分子物質，甚至直接降解成為CO₂ 和H₂O，接近完全礦化。

廢水處理中的光催化氧化法

TiO2hv  e + h+ h+ + H2O  OH + H + e- + O2  O2- O2- + H+  HO2 TOC + Ox  TOC

(partially oxidized species) + CO2 + H2O

Formation of radicals

Photo-generation electron/hole pairs

Radical oxidation of organic compound

(41)

41

具八面體配位之d0 _與d10_{軌域之過渡金屬元素的氧化物光觸}

媒

[Maeda et al., 2007]

(42)

42

VOCs-我們身邊的隱形殺手

 VOCs的種類：苯、甲苯、甲醛、低級醇和酮等等  VOCs的來源：油漆、塗料、溶劑、消毒劑等等  VOCs的危害：低度：對眼、鼻、喉等有刺激性中度：破壞肝臟、胃等器官及中樞神經系統高度：造成某些器官癌變

(43)

• 發展高活性光催化氧化降解有機物的新

觸媒:

– 降低反應所需消耗能量

– 減少化學物使用量

– 移除在半導體製程中產生的total organic

carbon (TOC)

目標

(44)

44

光催化降解污染物

 Photocatalysis is able to degrade contaminants that are not accessible by other technologies

 The feasibility is proven up to first industrial applications

 Total mineralization is possible but not always necessary-the process can be adjusted to economics

 The photocatalytic process must be adjusted to the waste problem

(45)

45

 設備結構簡單，反應條件溫和，

操作條件容易控制

 氧化還原性強，無二次污染

 TiO

₂

化學穩定性高、無毒、價廉

光催化降解污染物的特點

(46)

46

光催化降解污染物面臨的難題

 大部分有机物光催化降解的量子效率都低于

20%：



<15%：苯、甲苯、己烷、二氯乙烷



<1%：四氯化碳、二氯甲烷、氯仿、氯乙烯

(47)

Role of Promoters in Photocatalytic Process

Metal attracts free electron slows recombination and

promotes radical formation 47

 研發高比表面積的光觸媒  加入適當的助觸媒，促進光觸媒光激發電子-電洞對的分離效率 O2/CO2 Photocatalyst particle Photon Charge

separation _{Reaction site} Life time Mobility R e c o m b in a t i o n e - + h + Cocatalysts (Pt, NiO, RuO₂) Pollutant Acceptor

高活性光觸媒研發方向

) M(e e M (energy) TiO h e ₂           

(48)

Experimental Setup for

Batch Reactivity Testing

UV lamp, Halogen lamp

Water bath/ shaker/

(49)

(50)