本研究之目的在於製備化學迴圈程序用之高活性載氧體，選取硝酸鎳以及硝酸鐵作為前驅物，以部分因素實驗設計法（factorial fractional design）對5個主要影響實驗之變因（水量、鍛燒溫度、分散劑含量、硝酸鎳含量、硝酸鐵含量）進行探討，藉由溶膠凝膠法（sol-gel method）製備出16組複合金屬氧化物。
以熱重分析儀（TGA）進行複合金屬載氧體的反應性測試。以X光繞射儀（XRD）、場發射掃描式電子顯微鏡（FESEM）、能量散射光譜儀（EDS）與比表面積量測儀（BET）進行載氧體反應前後的材料特性分析。TGA測試結果顯示，將硝酸鎳與硝酸鐵以1：3莫耳比混合，並添加3 g的聚乙二醇（PEG）作為分散劑，於15 mL的去離子水中含浸後，再於1000°C下鍛燒6小時所得的載氧體，其整體反應性最佳。分析16組載氧體的反應性測試結果，得知前驅物硝酸鎳含量為影響載氧體反應性的主要因素。根據此測試結果，針對硝酸鎳含量進行單一實驗變因分析，得知載氧體的最佳製備參數為Ni(NO3)2：150 mmol、 Fe(NO3)3：30 mmol、鍛燒溫度：1000°C、PEG：3 g以及H2O：15 mL，而此載氧體亦同時具有純氧化鐵與氧化鎳的優點，且其還原速率較純氧化鎳快。
多重循環還原氧化反應測試結果顯示，未添加多孔性材料作為擔體的載氧體均有聚集之現象產生。載氧體以濕式含浸法（wet impregnation method）擔載於擔體後，其反應性與熱穩定性均有顯著的提升，可作為具實用性之載氧體。

In this research, a highly active oxygen carrier for chemical looping combustion (CLC) process was developed with using nickel and iron nitrate as precursors, respectively. Effects of the preparation variables on the oxidation and reduction activities of composite oxygen carriers were systematically examined using the fractional factorial design (FFD). The following preparation parameters were investigated in the present FFD analysis: amount of water, calcination temperature, amount of dispersant, amount of nickel nitrate, and amount of iron nitrate. Sixteen kinds of Ni-Fe composite oxygen carrier were prepared by sol-gel method according to the preparative conditions of FFD.
Reactivities of oxygen carrier were evaluated in a thermogravimetric analyzer (TGA). The effects of the preparation parameters on the structure, and physicochemical properties of the composite oxygen carriers were elucidated by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), and Brunarer-Emmett-Teller (BET) adsorption. The most active sample was obtained under these conditions: 0.01 mol of Ni(NO3)2, 0.03 mol of Fe(NO3)3, 3 g of PEG, 15 mL of water, and calcination at 1000°C for 6 h. The analysis of variance table (ANOVA) indicate the effect of amount of nickel nitrate is the key factors influencing the redox activity of composite oxygen carrier.
According to the results, the optimal amount of Ni/Fe molar ratio, 5, was further found to obtain an oxygen carrier with high reduction and oxidation activities. The agglomeration of oxygen carrier resulted in the decrease of activity. After the immobilization of composite oxygen carrier on a porous ceramic filter, the thermal stability of oxygen carrier was enhanced greatly and could be used in CLC process practicably.

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