Pd/C觸媒應用於燃料電池之可行性評估

The Preparation of Pd/C and its uses for fuel cell applications

林志雄(Chih-Hsiug Lin)

指導教授 ： 林昇佃

元智大學/工程學院/化學工程與材料科學學系/碩士(2000年)

摘要

本研究之主要目的為製備高分散度、低H-hydride比例、無Pd-C固溶相之Pd/C觸媒，並將其製成電極，期能進ㄧ步取代燃料電池所使用之Pt/C商用觸媒。
本研究之觸媒製備以含浸法為主，使用氫氣或NaBH4為還原劑，實驗結果顯示，改變還原條件比觸媒製備方法對Pd分散度影響更大，觸媒經高溫抽真空處理會使其氫吸附量下降，而以氫氣還原後之觸媒，太低之抽真空處理溫度，無法去除觸媒表面吸附之氫原子，所以氫氣還原之觸媒其氫氣吸附量皆不高，但經TEM分析得其金屬平均粒徑卻很小；此外，HRTEM分析發現，經氫氣處理之Pd/C觸媒有產生PdCx固溶物的現象，可能也是影響氫吸附的原因之一。而以NaBH4(pH=12)進行還原之Pd/C觸媒，經 373K抽真空處理後分析，得到高於1的分散度(Had/Pd)，應是產生spillover現象所致。
將觸媒製成電極進行氫氣氧化半電池測試，發現不同製法與還原條件所得觸媒對CO容忍度有所不同，以氫氣於473K還原及NaBH4 pH=12還原之自製觸媒，對CO 之容忍度皆比商用觸媒-147差，但商用觸媒-147卻具有比商用Pt/C及Pt-Ru/C更好之 CO 容忍度，顯示Pd/C觸媒具有燃料電池應用的潛力，而在電極特性的CV分析中發現，利用Pd-O還原峰面積計算得知的電極活性面積與分析所得電催化活性無直接關係。

關鍵字

燃料電池

並列摘要

The study aimed to prepare Pd/C catalysts with high dispersion , low hydride ratio and no PdCx solution formation. Such catalysts are expected to have fuel cells applications.
The catalysts were prepared main by impregnation. Hydrogen adsorption was used to characterize the chemisorption and hydride ratio after the catalyst was reduced with different methods. An evacuation at high temperatures was find to reduce hydrogen chemisorption. However, an evacuation at lower temperatures was incapable of removing surface hydrogen when a hydrogen reduction was used. The hydrogen adsorption measurement is concluded not applicable when Pd/C catalyst is reduced with hydrogen. The catalysts reduced for NaBH4(pH=12),and to vacuum at 373K can obtain more than one of the dispersion (Had/Pd). It’s the phenomenon for spillover.
The catalysts to made electrodes than to used IV test. It can obtain different tolerance in regard to CO for different preparation method and reduction condition. The catalysts to reduced for hydrogen at 473K and NaBH4(pH=12),the tolerance is bad for industrial Pd/C. But the industrial Pd/C has the CO tolerance more than industrial Pt/C and Pt-Ru/C. To display the Pd/C potential for apply fuel cell. And at CV curve ,it’s no direct related for to calculated the electrode activity area from Pd-O and the electroreactivities.

並列關鍵字

Fuel cell

參考文獻

1. Leger, J.M., and C. Lamy, Ber. Bunsengenes Phys. Chem. , 94 (1990) 1021.

3. K. Nishimura, K. Machida, M. Enyo, J. Electroanal. Chem., 251 (1988) 117.

5. R. R. Adzic, D. N. Simic, D. M. Drazic, J. Electroanal. Chem., 80 (1977) 81.

6. K. Nishimura, K. Kunimatsu, K. Machida, M. Enyo, J. Electroanal. Chem. 260 (1989) 181.

7. K. Nishimura, K. Kunimatsu, M. Enyo, J. Electroanal. Chem. 260 (1989) 167.