以金屬-Ti-MCM-41光觸媒進行液相二氧化碳光催化還原之研究

Abstract

二氧化碳吸收技術中，乙醇胺與氨水為目前工業上最普遍被使用之吸收劑，故本研究之宗旨為利用乙醇胺與氨水為液相二氧化碳光催化還原之二氧化碳吸收劑，並將其兩者之二氧化碳光催化還原效率與文獻中常用之氫氧化鈉做比較，了解其可行性。而本研究使用之觸媒以ICP-AES、XRD、BET、TEM、FTIR、UV-VIS與ESCA等方法鑑定其物化特性。再利用不同操作參數進行二氧化碳光催化還原實驗，探討其二氧化碳還原效率，以尋求最適操作條件。 本研究首先利用水熱法合成光觸媒Ti-MCM-41(100)，並以此光觸媒進行三種不同吸收劑之二氧化碳光催化還原測試。研究結果顯示當使用乙醇胺為吸收劑時，其有最高的二氧化碳還原產物甲烷之產量。而針對乙醇胺探討不同金屬(Ti, V, Zn, Zr, Mn, Mo)觸媒之催化效率，研究結果顯示當使用Mo與Ti雙金屬植入中孔洞材MCM-41中時有最高的甲烷產量。接著再針對此Mo-Ti-MCM-41雙金屬觸媒去探討不同金屬含量對於催化效率之影響，結果顯示當Si/(Mo+Ti)之莫耳比為50時，其有最高的甲烷產量，甲烷產量可達1.83μmol/g．hr。研究亦發現當反應溫度為40℃時甲烷產量明顯高於25℃。

Among the carbon dioxide absorption technologies, the ethanolamine and ammonia are two of the most popular absorbents. Therefore, this research used ethanolamine and ammonia as liquid sorbents for the photocatalytic reduction of carbon dioxide so that the CO2 can be absorbed and then reduced into valuable energy sources. The photocatalysts were prepared and their chemical and physical properties of the photocatalysts were analyzed by ICP-AES, XRD, BET, TEM, FTIR, UV-VIS and ESCA. To effectively increase the methane production rate by CO2 reduction process, the optimization parameters were also investigated in this study. The Ti-MCM-41(100) was firstly synthesized by hydrothermal method to evaluate the possibility of using CO2 absorbents, ethanolamine and ammonia, as the reducing agents. The results showed that ethanolamine had a better CO2 reduction efficiency and thus this study was then focused on using the ethanolamine as the absorbent and reducing agent. And several metals (V, Zn, Zr, Mn, Mo) were implanted into the mesoporous material of MCM-41 to form the metal-Ti-MCM-41 photocatalysts. The results showed that bi-metallic Mo-Ti-MCM-41(50) was the best photocatalyst for the CO2 reduction to form methane, the best methane production rate was 1.83μmol/g．hr. And when the reaction temperature was 40℃, the methane production rate was higher than that at 25℃.