Ni/V2O3催化劑的協同效應對二氧化碳甲烷化反應的影響

Abstract

本實驗改變不同的Ni/V2O3比例、反應溫度、觸媒附載量以及合成方法去探討Ni/V2O3的協同效應對於二氧化碳甲烷化活性的影響。其中，我們使用X光粉末繞射儀、感應耦合電漿原子發射光譜分析儀、X光光電子能譜儀和熱程控還原反應去鑑定合成之材料。本實驗以溶膠凝膠法、水熱法以及含浸法製備催化劑去探討不同合成方法對於二氧化碳甲烷化之影響。由X光光電子能譜儀和熱程溫控還原反應的結果可知在Ni/V2O3材料中存在著Ni-V-O的固溶體。在溶膠凝膠法的實驗中，材料組成在Ni/(Ni + V2O3)莫爾百分比是40%的條件下，有最高比例的三相介面，並在反應溫度400牵C的條件下有最佳的甲烷產率。隨著觸媒量增多時，甲烷產率也隨之提高。接著利用含浸法與水熱法合成最佳比例的觸媒，結果顯示由於溶膠凝膠法所合成的顆粒分散較佳，具有最高的轉換效率。在最佳比例的Ni/V2O3觸媒，反應溫度為400牵C的條件下，二氧化碳轉換效率可達93(1)%，並且甲烷選擇率接近100(1)%。在催化劑的穩定性方面，55小時內並未出現衰退的現象。

The synergetic effect between Ni and V2O3 in carbon dioxide methanation was investigated using compositions, different loading, reaction temperature, amount of catalysts and synthetic routes. The catalysts were characterized by powder X-ray diffraction (PXRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). Formation of Ni–V–O solid solution was confirmed by XPS and TPR studies. The optimal Ni/(Ni + V2O3) molar percent for the highest methane yield is found to be 40. The conversion of carbon dioxide to methane was increased as the amount of loading catalysts increased. Catalysts with Ni/(Ni + V2O3) molar percent of 40 were synthesized by sol-gel, hydrothermal and impregnation methods to study their catalytic activity for carbon dioxide methanation. The results indicate that catalyst prepared by sol-gel method exhibits better performance compared with other methods due to its well-dispersed particles that optimized the amount of triple phase boundaries (TPB) between gas phase and the catalyst. The catalyst with Ni/(Ni + V2O3) molar percent of 40 showed the best activity among other catalysts with the carbon dioxide conversion ~93(1) %, the selectivity of methane ~100(1) % at 400ºC, and very stable catalytic activity for 55 hours.