CuO/Ce1-xZrxO2/Al2O3觸媒於富氫中CO的選擇性氧化反應研究

Selective oxidation of CO in excess hydrogen over CuO/Ce1-xZrxO2/Al2O3 catalysts

張煒謙(Woei-Chian Chang)

指導教授 ： 陳吟足

國立中央大學/工學院/化學工程與材料工程學系/碩士(2006年)

摘要

本研究將Al2O3懸浮於Ce4+、Zr4+前驅鹽溶液中，利用共沈澱法製備Ce1-xZrxO2/Al2O3擔體，採臨濕含浸法製備CuO/Ce1-xZrxO2/Al2O3觸媒，探討觸媒於富氫中CO選擇性氧化反應特性。
XRD、TPR證實，適量的ZrO2可固溶入CeO2/Al2O3，增強Ce1-xZrxO2/Al2O3的redox特性；引入Al2O3可增加Ce1-xZrxO2共氧化物的分散性，而不影響其結構及redox特性。脈衝式CO吸附實驗與XPS證實，於CuO/Ce1-xZrxO2/Al2O3中引入少量ZrO2可促使觸媒產生更多的活性中心Cu+；而引入Al2O3則會影響Ce0.9Zr0.1O2誘發Cu+產生。少量ZrO2的引入，可增強擔體的redox特性，有助於CuO/Ce1-xZrxO2/Al2O3觸媒於CO選擇性氧化反應之活性；引入Al2O3可增加Ce1-xZrxO2利用度，但不利於反應，引入量不宜過多。CuO之負載量以7%為最佳。以7%CuO/Ce0.9Zr0.1O2/Al2O3(20%)為觸媒，轉化率達100%的溫度為95~100℃(F/W=10,000 mlhr-1g-1)，較7%CuO/ CeO2/Al2O3觸媒之105~110℃降低10℃。7%CuO/Ce0.9Zr0.1O2/Al2O3於100℃左右，都可維持近100%的選擇率，是一具有高活性與高選擇率的觸媒。CO2及H2O雖會降低7%CuO/Ce0.9Zr0.1O2/ Al2O3觸媒活性，使之達100%轉化率溫度升高至155~160℃，但觸媒仍能維持90%左右的選擇性及不錯的穩定性。7%CuO/Ce0.9Zr0.1O2/Al2O3(20%)觸媒對反應氣體具有高處理容量，提高質流比(F/W)2~3倍仍可維持高選擇率。

關鍵字

氧化鈰 ； 選擇性CO氧化反應 ； 氧化銅

並列摘要

Preferential CO oxidation in hydrogen (PROX) is one of the key-techniques in developing low
temperature polymer electrolyte membrane fuel cells (H2-PEMFC). Numerous Au-based and Pt-based
catalysts have been studied on the selective oxidation of CO. But none of these noble catalysts can
prevent significant losses of hydrogen by oxidation. In previous work, we have found that an appropriate
amount of ZrO2 introduced into cerium oxide not only promoted the redox property of the resulted
mixed-oxide Ce0.9Zr0.1O2 but also enhanced the selective oxidation of CO on CuO/Ce0.9Zr0.1O2. The best
catalyst of 7%CuO/Ce0.9Zr0.1O2 is a promising candidate for replacing noble catalysts used in a PROX
unit of H2-PEMFC system for removing CO. But the mixed oxide Ce0.9Zr0.1O2 from co-precipitation has
a surface area only about 70 m2/g, and does not have good mechanical strength and forming properties.
This work will use Al2O3 as a support for mixed oxide of Ce0.9Zr0.1O2 to improve its dispersion,
mechanical strength and the easiness of forming. A new supported oxide of [Ce0.9Zr0.1O2/Al2O3] will be
prepared using the co-precipitation-deposition method, its redox property and the selective oxidation of
CO on CuO/[Ce0.9Zr0.1O2/Al2O3] catalyst will be examined.

並列關鍵字

CuO catalyst ； selective CO oxidation ； CeO2 oxide

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