制备活性炭负载K2CO3用于催化餐饮废油合成生物柴油

以K₂CO₃为催化剂,工业碱木质素(KL)为活性炭(AC)前体,在管式电阻炉中经一步共混活化(K₂CO₃/KL质量比为0.6、活化温度800℃、N₂流量100cm³/min、活化时间2h)制备K₂CO₃/AC固体碱催化剂,用于餐饮废油与甲醇的酯交换反应合成生物柴油。对制备的固体碱催化剂进行了X-射线衍射(XRD)、BET表面积及扫描电镜(SEM)表征。考察了反应温度、催化剂用量、反应时间、醇油摩尔比等因素对餐饮废油转化为生物柴油产率的影响。结果表明当反应时间2h、反应温度60℃、醇油摩尔比15:1、催化剂为原料油质量的3.0%时,生物柴油最大产率为87.5%。考查了催化剂的循环利用效果,结果表明催化剂能循环利用3次,第3次利用时生物柴油的产率仍达到80.7%。

Preparation of K2CO3 supported activated carbon for the transesterification of waste cooking oil to biodiesel

K₂CO₃ supported activated carbon (AC) as solid catalyst was prepared by directly mixing K₂CO₃ with technical Kraft Lignin (KL) with the mass ratio of 0.6 and subsequently activating at 800℃ for 2h under 100cm³/min of N₂ flow rate in a tubular furnace. The obtained solid base catalyst was characterized by XRD,BET surface area and SEM. It was found that the catalyst possessed mesoporous structure with an average pore diameter of 10 nm and a good dispersion of K₂CO₃ on the surface of AC support. The prepared K₂CO₃/AC solid catalyst was used for the transesterification reaction of waste cooking oil (WCO) with methanol in batch reactor. The effects of various parameters,such as reaction temperature,amount of catalyst,reaction time,and molar ratio of methanol to WCO,on biodiesel yield were investigated. A maximum biodiesel yield of 87.5% was obtained under the optimal condition as reaction temperature of 60℃,catalyst amount of 3.0%,methanol to WCO molar ratio of 15:1 and reaction time of 2h. The effect of repeated use of K₂CO₃/AC catalyst on biodiesel yield was tested. The results indicated that the catalytic activity remained 80.7% when the catalyst was employed for the third time.