奈米粒子製造技術，可用來製備高性能之觸媒，跟以傳統製程產製的工業觸媒相比較，使用該技術所得到之觸媒，其活性及選擇性都高出許多，而且能夠於較低溫度下進行反應，降低操作時所消耗的能量，是個值得研發的領域。
本論文主要是研究奈米金屬氧化物擔體觸媒，用於以一氧化碳為還原劑之一氧化氮還原反應。首先，我們製備各種不同金屬氧化物擔體觸媒，再以填充床反應器來測定他們的活性與效能，並探討各種操作條件對轉化率之影響。接下來，以TPD、TPO、TPR、XRD、SEM、TEM及BET等分析儀器來測定擔體觸媒的表面性質，根據觸媒表面性質的鑑定的結果，探討影響觸媒活性的因素。最後，以篩選出來最佳擔體觸媒進行反應動力學之探討，藉此了解反應模式。
實驗結果顯示，觸媒上金屬氧化物的種類與含量、擔體種類、觸媒擔體製備方式、觸媒製備時的鍛燒溫度、反應前還原處理、氣體進料濃度比及進料氧氣等，都會影響一氧化氮還原反應。以CeO2為擔體之不同單金屬氧化物(Fe2O3、NiO、MnO2、MoO3、Cr2O3、Co3O4、CuO)觸媒中以NiO/CeO2觸媒對一氧化氮還原反應具有最佳活性，CuO/CeO2觸媒次之。將硝酸鎳溶液含浸於不同擔體(γ-Al2O3、CeO2、TiO2、V2O5、ZrO2)中，製成NiO擔體觸媒，結果仍以NiO/CeO2觸媒活性為最佳。改變NiO/CeO2觸媒中NiO的含量，發現鎳含量為5Wt%時，NiO/CeO2擔體觸媒具有最佳活性。分別以檸檬酸溶膠凝膠法、共沈澱法、逆微胞法以及PAA溶膠凝膠法等不同方式來製備奈米級二氧化鈰擔體，再製成NiO/CeO2觸媒，活性測試結果顯示，以檸檬酸溶膠凝膠法所製備之CeO2為擔體之觸媒活性最佳。
以含鎳5Wt%之NiO/CeO2觸媒，在不同進料濃度比CO：NO（3：1，2：1，1.5：1，1：1）之下進行NO之還原反應，發現進料濃度比為2:1為最佳進料條件，在此條件下，可獲得最高之NO轉化率。若以CO或是H2氣體對NiO/CeO2觸媒做前還原處理，再進行催化反應，發現催化活性降低。進料反應過程中添加氧氣，對於一氧化氮還原反應亦有相當影響，反應溫度在240℃下，NiO/CeO2觸媒會喪失其催化活性。鍛燒溫度也會影響擔體觸媒的催化活性，在300～600℃下鍛燒觸媒中，以500℃下鍛燒的觸媒具有較佳的活性。
由BET分析得知，以檸檬酸溶膠凝膠法所製備出之NiO/CeO2觸媒具有較大之表面積，是此擔體觸媒催化活性會優於以其他方法所製備擔體觸媒的原因之一。根據NO-TPD實驗結果，發現添加NiO或是CuO在CeO2擔體上，對於吸附一氧化氮之量皆有很大的幫助。由CO-TPR實驗結果得知，NiO/CeO2及CuO/CeO2擔體觸媒，在較低溫處就有被還原的現象，而且CuO/CeO2觸媒被還原溫度比NiO/CeO2還低，這現象間接說明為何CuO/CeO2觸媒在低溫時會優於NiO/CeO2觸媒。由XRD分析得知，以硝酸鈰與其它金屬鹽類為原料，採用檸檬酸溶膠凝膠法且在500℃鍛燒所製備之觸媒，為二氧化鈰與其它金屬氧化物之混合物，而不會形成Peroveskite型之晶相化合物，可用來比較觸媒活性優劣；並且以SEM及TEM得知，不管以檸檬酸溶膠凝膠法、共沈澱法、逆微胞法以及PAA溶膠凝膠法等不同方法，皆可以製備出奈米級二氧化鈰擔體，然而粒徑不同。
最後，本研究針對NiO/CeO2觸媒進行動力學研究，企圖找出適用於一氧化碳還原一氧化氮的反應機構模式。由於NiO/CeO2觸媒一氧化碳程溫還原反應之起始溫度與活性測試測得之反應起始溫度相符合，並且由一氧化氮程溫氧化實驗也得知，經過被還原之NiO/CeO2觸媒有被一氧化氮氧化的現象。以上現象皆顯示反應機制應該是屬於氧化還原機制。藉由動力學模式的套適結果，Mars-Van Krevelen模式、Langmuir-Hinshelwood模式（兩種反應物分別吸附於相同以及不同的活性座上）以及Eley Rideal模式皆有不錯的套適結果，但以Mars-Van Krevelen模式最佳，則由反應模式套適結果，更進一步確定NiO/CeO2觸媒催化一氧化氮還原反應機制可以用Mars-Van Krevelen model表示。

The nano-particle technology is appropriate for producing high performance catalysts. These catalysts process a markedly higher activity and selectivity compared with the conversional ones. The catalysts can be also used for reacton at a relativity low temperature, thereby reducing energy consumption.
In this study, the performance of the supported metallic oxide catalysts for catalytic reduction of nitric oxide with carbon monooxide as a reducing agent were investigated. First, we prepared various kinds of supported metallic oxide catalysts. Then the activities of the prepared catalysts were evaluated by a packet-bed reactor. Then these prepared catalysts were characterized with TPD, TPO,TPR, XRD, SEM, TEM and BET in order to understand the effects of the catalyst characters on the catalystic activities. Finally, a kinetic study on the NO reduction over the best catalyst with CO as a reducing agent was carried out to figure out a suitable reaction mechanism.
The experimental results indicate that active species, supports, the different method of making the support, calcination temperature, reducing pretreatment, different concentration ratio of reaction gas(CO/NO) and oxygen are important factors affecting catalyst activity. NiO/CeO2 is the most active catalyst among CeO2-supported single metal oxide catalysts (Fe2O3、NiO、MnO2、MoO3、Cr2O3、Co3O4、CuO). CuO/CeO2 is the second one. With NiO as the active species, CeO2 is also found to be the most suitable support. When changing nickel loading ratio in NiO/CeO2, we discover that the NiO/CeO2 catalyst with 5 wt % nickel is the most active. When we use different kinds of method of making nano-CeO2 to, we found that NiO/CeO2 whose CeO2 is made by citric-acid sol-gel is the most active.
Knowing that the feed concentration ratio of CO to NO might affect the reduction of NO, three different feed concentration ratios (CO:NO=1：1, 1.5：1, 2：1, 3：1) were tested. When NiO/CeO2 with 5 wt % Ni as the catalyst for the reducing of CO, experimental results reveal that the feed concentration ratio of CO to NO being 2 provides higher conversion of NO. However, the 5 wt %Ni/CeO2 prereduced by CO or H2 provides a lower activity than those not pretreated with CO or H2. The addition of O2 in the course of reaction would result losing the conversion. Comparing the catalysts calcined at different temperatures reveals that the catalyst calcined at 500℃ is the most active.
We could realize that area of NiO/CeO2 whose CeO2 was made by citric-acid sol-gel method is bigger by BET analysis. So NiO/CeO2 which is made by citric-acid sol-gel method would be more active than others made by another methods. CeO2 and two catalysts (NiO/CeO2 and CuO/CeO2) were characterized by NO-TPD. The desorption patterns exhibit that adding NiO or CuO on the CeO2 would make catalyst adsorption more NO. The results of CO-TPR further indicate that CuO supported by CeO2 (CuO/CeO2) will be reduced easily at lower temperature than NiO supported by CeO2 (NiO/CeO2). This result indirectly indicated why CuO/CeO2 would be more active than NiO/CeO2 at low temperature. By the XRD results, we could know that catalysts made by citric-acid sol-gel method could use to compare activity without making another crystal we don’t want. By the SEM and TEM Patterns, we could realize that we could get nano-CeO2 by citric-acid sol-gel method, precipitation method, reverse micell method and PAA sol-gel method to obtain our purpose.
At the end of this study, a kinetic study on the NO reaction over the NiO/CeO2 catalyst with CO as a reducing agent was carried out to obtain a rate expression and to figure out a suitable reaction mechanism. We can realize that the reduced beginning temperature of NiO/CeO2 is similar to the activity beginning temperature of NiO/CeO2. And with the NO-TPO of the reduced NiO/CeO2 result, all phenomena shown that the reaction mechanism should be the Mars-Van Krevelen model. The results show that four models, Langmuir-Hinshelwood model-NO and CO adsorbed on two different kinds of active sites, Langmuir-Hinshelwood model-NO and CO adsorbed on the same kind of the active sites, Mars-Van Krevelen model and Eley Rideal model could fit well the data we obtained. Besides, Mars-Van Krevelen would fit best. With NO-TPD、 CO-TPD、 CO-TPR and NO-TPO results, all phenomena shown that the Mars-Van Krevelen model is the main reaction model for NiO/CeO2 using on NO reducing reaction with CO as a reducing agent.

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