鐵鹽含浸濃度對活性碳觸媒之氮氧化物還原活性之影響

Effect of Impregnation Concentration of FeSO4 in Activated Carbon Catalyst on the Reduction Activity of Nitrogen Monoxide

本研究利用椰殼含浸於不同濃度硫酸亞鐵溶液作為金屬活化劑以製備碳觸媒，並將製備成之碳觸媒應用於氮氧化物之還原。以比表面積分析儀（BET）、掃描式電子顯微鏡與／能量分散分析儀（SEM/EDS）、X射線繞射儀（XRD）分析碳觸媒之表面結構、孔隙特性及活性金屬氧化物之形態，研究中將所研製之碳觸媒以非選擇性觸媒還原法（NSCR）於不同溫度下，探討碳觸媒對於還原氮氧化物之活性。由表面及孔隙分析結果顯示，以硫酸亞鐵作為含浸劑可製得高鐵含量及高比表面積之碳觸媒。且其對氮氧化物之還原效率與碳觸媒之鐵鹽含量多寡、鐵之分散性有明顯相關。此型碳觸媒進行非選擇性觸媒還原反應（SNCR）之結果發現，當實驗條件為：甲烷（CH4）4000ppm，氮氧化物（NO）1000ppmv，含浸0.2M硫酸亞鐵所製成之碳觸媒對氮氧化物之轉化率僅有60%左右。硫酸亞鐵碳觸媒雖具有較高鐵含量，適當的比表面積，但可能因碳觸媒表面之鐵氧化物對於SNCR活性不高，因此無法顯現較高之反應活性。

The activated carbon catalysts were prepared by using coconut shell as the support matrix with iron sulfate as the activating agent and the prepared carbon catalyst were applied for the non selective reduction of NO with methane in reactor. The pore structure, surface area and iron content were identified by BET and SEM-EDS analysis, respectively. The non selective catalytic reductions of NO were carried out with the packing reactor with iron embedded carbon catalyst. The reduction activities were evaluated at the various reaction temperatures with different conditions. Based on the pore and surface analysis, it was found that the impregnating iron enhanced the pore development and also enriched the iron content in carbon catalyst. In this study, the reduction activity of iron embedded carbon catalyst strongly depended on the iron content in carbon matrix and the condition of iron oxides dispersion on the carbon surface. The non selective catalytic reduction experiment of NO showed 60% conversion with appreciate amount of prepared catalyst, via 4000ppm CH4, 1000ppmv NO, 0.3g 0.2M Fe-AC at 600℃. However, the carbon catalyst presented a good pore property and optimum surface area, the reduction activity for NO is not good enough in the non-selective catalytic reduction.