奈米級LaBO3（B = Fe, Co, Ni, Mn）金屬氧化物觸媒應用於以一氧化碳為還原劑催化二氧化硫還原反應之研究

Catalytic Reduction of Sulfur Dioxide with Carbon Monoxide as a Reducing Agent over Nanosized LaBO3 (B = Fe, Co, Ni, Mn) Metal-Oxide Catalysts

本研究以溶膠凝膠法製備奈米級波洛斯凱特(Pervoskite)型觸媒LaBO3(B = Fe, Co, Ni, Mn)，藉由X 光繞射分析(XRD)、掃瞄式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)分析，探討波洛斯凱特型觸媒之特性。實驗結果發現，以溶膠凝膠法製備之波洛斯凱特型觸媒的顆粒介於30-50nm。並探討它們用於以一氧化碳為還原氣體進行二氧化硫還原之性能。在LaMnO3、LaFeO3、LaNiO3、LaCoO3 四系列觸媒中，以LaFeO3之活性最好，LaNiO3次之。使用LaFeO3觸媒進行SO2還原反應，結果顯示CO和SO2最適當的進料比為2.5。反應過程中加入不同濃度的氧氣(0.1%及0.5%)，LaFeO3觸媒會失去其催化活性，而且氧氣濃度越高，失活現象更是明顯。以LaFeO3為觸媒，使用不同的還原氣體(CO或CH4)進行反應測試時，我們發現以CO為還原氣體最具活性。

A series of perovskite type LaBO3 (B = Fe, Co, Ni, Mn) catalysts were prepared by sol-gel method. These catalysts were characterized by XRD, SEM and TEM. The size of nanosized perovskite type LaBO3 (B = Fe, Co, Ni, Mn) particle synthesized by sol-gel method is about 30-50nm. These catalysts were investigated for the catalytic reduction of SO2 to elemental sulfur with CO as a reducing agent. For the series of LaMnO3、LaFeO3、LaNiO3 and LaCoO3 catalysts, LaFeO3 was the most active catalyst, and LaNiO3 the second most active. Using this LaFeO3 catalyst, we found that the optimal feed ratio of CO/SO2 is 2.5:1. However the addition of O2 (0.1 % and 0.5 %) in the course of reaction would result in a decline in the conversion, and the decline is more obvious when more O2 is added. When we use LaFeO3 catalyst, CO as a reducing agent exhibits a higher activity than the CH4.