由廢咖啡渣製備固體酸觸媒及其催化活性的研究

廢咖啡渣經由不同的碳化處理以增加其表面積，再用不同硫酸濃度處理後，經過濾與乾燥即為碳化固體酸觸媒。製備所得之固體酸觸媒樣品，用分析儀器如XRD、UV、TGA及NH_3-TPD等進行物性鑑定，並用乙醇與乙酸的酯化反應，作為固體酸觸媒的催化活性測試反應。由XRD結果顯示，廢咖啡渣在碳化後，其XRD圖譜在2θ=15～30°及2θ=40～50°，出現兩個寬的繞射信號，分別為非晶型的碳及晶型的石墨（graphite）的特性波峰。其UV圖譜在波長～250nm處，出現明顯的吸收信號，為-SO_3H接到碳結構上的特徵吸收，證明-SO_3H成功地接到碳化廢咖啡渣上，其信號強度隨硫酸濃度而增強，此現象與NH_3-TPD結果一致。這些碳化的固體酸對乙醇與乙酸的酯化反應都有良好的催化活性，在83℃下，轉化率可達～97%。

關鍵字

固體酸；廢咖啡渣；碳化；磺酸化；酯化反應

並列摘要

The solid acid catalysts were prepared by two sequential procedures including the carbonization and sulfonation of spent coffee grounds (SCGs) to increase its BET surface area and acidity. The synthesized samples were characterized by techniques such as XRD, UV, TGA and NH_3-TPD. The esterification of ethanol and acetic acid was used as a model reaction to identify the catalytic activity of the synthesized catalysts. Two broad XRD characteristic diffraction peaks locate at 2θ=15°-30° and 2θ=40°-50°, these peaks belong to amorphous carbon and crystalline graphite (graphite), respectively. A broad characteristic absorption peak of -SO_3H appear at ~250nm in UV spectra, suggested that the functional group of -SO_3H was successfully grafted onto the carbonized SGGs. Further, the characteristic peak was found to be increased with the concentration of sulfuric acid and this phenomenon was also consistent with NH_3-TPD results. These carbonized solid acids have good catalytic activity on the esterification of ethanol and acetic acid, and the conversion can reach ~97% under 83℃.

並列關鍵字

solid acid ； spent coffee grounds (SCGs) ； carbonization ； sulfonation ； esterification

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由廢咖啡渣製備固體酸觸媒及其催化活性的研究

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