碳基燃料反應(yīng)特異性及陽極催化動力學(xué)研究

孫春文

摘 要：研究可以直接電化學(xué)氧化碳?xì)浠衔锶剂系男滦完枠O和外重整器是研制碳基燃料固體氧化物燃料電池的核心。

該研究發(fā)展了一種制備微納結(jié)構(gòu)花狀氧化鈰的新方法，負(fù)載鎳后是一種性能優(yōu)良的低溫甲烷部分氧化和水汽重整催化劑，通過調(diào)整合適的CH4/O2比或水蒸汽/碳（S/C）比可以有效地抑制積碳；甲烷水蒸汽重整可以在較低溫度（550 ℃）下發(fā)生，590 ℃時催化劑的使用壽命超過1 000 h，轉(zhuǎn)化率超過80%；設(shè)計(jì)、制作了單室甲烷水蒸氣重整反應(yīng)器和500 w疊片式甲烷水蒸氣重整反應(yīng)器，性能穩(wěn)定。

首次利用先進(jìn)的球差校正掃描透射電鏡（STEM）和同步輻射X射線吸收譜（XAS）技術(shù)對雙鈣鈦礦結(jié)構(gòu)Sr2CoMoO6在不同氣氛下的結(jié)構(gòu)演變進(jìn)行了研究，發(fā)現(xiàn)在高溫還原性氣氛下，Sr2CoMoO6中會形成大量氧空位，制備的一體化電池SCMO-LSGM/LSGM/SCCO-LSGM在850 ℃下輸出功率密度達(dá)到1.63 W/cm2，SCMO作為電極制備的對稱電池在650 ℃下穩(wěn)定工作100 h。用溶膠-凝膠法制備了多孔核殼結(jié)構(gòu)的Sr0.88Y0.08TiO3（YST）-Ce0.8Sm0.2O1.9（SDC）復(fù)合材料，研究結(jié)果表明YST@SDC復(fù)合陽極具有優(yōu)異的抗積碳性能，是一種有希望的碳?xì)浠衔锶剂匣鵖OFCs的陽極材料。利用同步輻射真空紫外-分子束質(zhì)譜（SR-MBMS）原位技術(shù)，首次研究了碳?xì)浠衔锛淄?、乙烯、丁烷、異辛烷等在SDC浸漬的Ni基陽極上的催化裂解機(jī)理。發(fā)現(xiàn)納米陽極降低了CH4裂解溫度、具有高的催化活性。通常認(rèn)為乙烯在催化劑上的積碳速度非常的快，分子束質(zhì)譜分析發(fā)現(xiàn)在浸漬SDC納米粒子的陽極上生成了乙烯，但實(shí)驗(yàn)沒有觀察到積碳，說明SDC浸漬的Ni基陽極是非?？狗e碳的。

該研究為發(fā)展抑制積碳的新方法提供了思路。最先研究了鈣鈦礦Sr1-xCexCoO3-delta（x：0.05～0.15）用于中低溫SOFC陰極材料，顯示出優(yōu)異的氧還原特性，在700 ℃下，30 wt.%SDC和SCCO005形成的復(fù)合陰極的電池輸出功率密度高達(dá)1.01 W/cm2；利用中子粉末衍射研究了其不同組分的結(jié)構(gòu)，很好地與性能關(guān)聯(lián)起來，相關(guān)工作已申請了兩項(xiàng)中國發(fā)明專利。

關(guān)鍵詞：固體氧化物燃料電池 陽極 碳?xì)浠衔?重整 反應(yīng)動力學(xué)

Abstract：Alternative anodes that can directly electrochemical oxidation of hydrocarbon fuels and reformers are two key technologies to develop carbon-based solid oxide fuel cells （SOFCs）. The structural evolution of double-perovskite Sr2CoMoO6（SCMO） during reduction/oxidation treatment was firstly clarified by means of XRD， XAS and STEM. Reduction causes oxygen vacancies and oxygen disordering，and lowers the average valence state of Mo for charge balance.Furthermore， Sr2CoMoO6 has been investigated as electrodes for SOFCs.The peak power density of a La0.9Sr0.1Ga0.8Sr0.2O3（LSGM） monolith supported cell is up to 1634 mW cm-2 at 850℃. The peak power density of a symmetrical fuel cell SCMO-LSGM/LSGM/SCMO-LSGM reaches 700 mW cm-2 at 850 ℃. The cell shows excellent long-term stability at 650 ℃ for more than 100 h. These results demonstrate that SCMO is a promising alternative material as anode for low-temperature solid oxide fuel cells as well as both electrode materials for symmetrical SOFCs. A porous Sr0.88Y0.08TiO3（YST）-Ce0.8Sm0.2O1.9（SDC）composite with a core/shell structure has been prepared with a sol-gel method and evaluated as an alternative anode for SOFCs.When CH4 was used as fuel， the peak power density of the single cell reached about 150 mW cm-2 at 900 ℃. It demonstrates that YST coated SDC composite is a promising alternative anode for SOFCs with hydrocarbon fuels. The molecular-beam spectrometric technique coupled with tunable synchrotron vacuum ultraviolet photoionization is applied to reveal the catalytic mechanism of methane over Ni-based anodes with and without impregnated nano-sized SDC particles.It indicates that the impregnated SDC nanoparticles are highly catalytically active for methane decomposition.C2H4is observed when the impregnated Ni-SDC composites are used as the catalyst，suggesting that SDC coating also suppresses carbon deposition at the anodes of SOFCs.Perovskite Sr1-xCexCoO3-delta（x：0.05～0.15） have been prepared by a sol-gel method and studied as cathodes for IT-SOFCs.Sr1-xCexCoO3-delta materials have sufficiently high electronic conductivities and excellent chemical compatibility with SDC electrolyte.At 700℃，the peak power density of cells with Sr0.95Ce0.05CoO3-delta is 0.625 W cm-2 By forming a composite cathode with 30 wt.%SDC， the peak power density of the cell reaches 1.01 W cm-2 at 700 ℃，better than that of Sm0.5Sr0.5CoO3-based cathode.This demonstrates that Sr1-xCexCoO3-delta（x：0.05～0.15）-based materials are promising cathodes for an IT-SOFC.Key Words：Solid oxide fuel cells；Anode；hydrocarbon fuels；Reforming；Kinetics of reactions

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