CuO/Ce1-xSnxO2-Al2O3觸媒於富氫中CO的選擇性氧化反應研究

Selective Oxidation of CO over CuO/Ce1-xSnxO2-Al2O3 catalyst

王榕蔓(Rung-Man Wang)

指導教授 ： 陳吟足 ； 廖炳傑

國立中央大學/工學院/化學工程與材料工程學系/碩士(2007年)

摘要

本研究將Al2O3懸浮於Ce4+、Sn4+前驅鹽溶液中，利用共沈澱法製備Ce1-xSnxO2-Al2O3擔體，採臨濕含浸法製備CuO/Ce1-xSnxO2-Al2O3觸媒，探討觸媒於富氫中CO選擇性氧化反應特性。
XRD、TPR分析得知，適量的SnO2(x=0.1~0.3)可固溶入CeO2-
Al2O3，造成CeO2結構扭曲、鬆動，增強Ce1-xSnxO2-Al2O3的redox特性，x≥0.3時部分的SnO2則無法完全固溶入CeO2-Al2O3而有分離相形成。脈衝CO吸附與XPS分析顯示，CeO2中引入SnO2可促進觸媒產生更多的活性中心Cu+，而引入Al2O3對Ce0.9Sn0.1O2誘發Cu+產生是不利的。少量SnO2的引入，確實有助CuO/Ce1-xSnxO2-Al2O3觸媒於CO選擇性氧化反應之活性，擔體中以Ce0.9Sn0.1O2-20%Al2O3有最佳表現。CuO負載量為7%即接近最佳活性，7%CuO/Ce0.9Sn0.1O2-
20%Al2O3觸媒於轉化率達100%所需溫度(T100)比7%CuO/CeO2-20%
Al2O3降低5℃。脈衝式CO吸附證實，7%CuO/Ce0.9Sn0.1O2-20%Al2O3觸媒有最大CO吸附量，有最多活性中心Cu+，有最佳活性。選擇率方面，在反應溫度小於100℃前，都可維持100%的選擇率，是一個具有極高選擇率的觸媒。7%CuO/Ce0.9Sn0.1O2-20%Al2O3觸媒對反應氣體具有高處理容量，高質流比(F/W=10,000~40,000 mlhr-1g-1)仍可維持高選擇率。CO2及H2O雖會降低7%CuO/Ce0.9Sn0.1O2-20% 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%左右的選擇率及不錯的穩定性。

關鍵字

銅觸媒 ； 選擇性氧化 ； 選擇率 ； 轉化率

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 Ce0.9Sn0.1O2 but also enhanced the selective oxidation of CO on CuO/Ce0.9Sn0.1O2. The best catalyst of 7%CuO/Ce0.9Sn0.1O2 is a promising candidate for replacing noble catalysts used in a PROX unit of H2-PEMFC system for removing CO. But the mixed oxide Ce0.9Sn0.1O2 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 Ce0.9Sn0.1O2 to improve its dispersion, mechanical strength and the easiness of forming. A new supported oxide of [Ce0.9Sn0.1O2-Al2O3] will be prepared using the co-precipitation-deposition method, its redox property and the selective oxidation of CO on CuO/[Ce0.9Sn0.1O2-Al2O3] catalyst will be examined.

並列關鍵字

selectivity ； conversion ； Cu catalyst ； selective oxidation

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