Preparation and characterization of activated carbons from spirit lees by physical activation

  • 摘要: 白酒糟是典型的富含纤维素生物质过程残渣,以水蒸气及CO2为活化剂研究了制备白酒糟多孔炭(活性炭)的各种操作条件,包括炭化温度、活化温度、活化剂流量对多孔炭样品性能的影响规律,证明了利用白酒糟制备多孔炭材料的技术可行性。基于SEM、XRD、N2吸附对材料表面和孔隙的表征,并结合制备过程气相产物的实时监测,解析了白酒糟多孔炭制备过程的活化反应历程。结果表明,低温炭化和高温活化有利于提高多孔炭对碘和亚甲基蓝的吸附,水蒸气比CO2具有更高的反应活性。制备多孔炭的比表面积和孔体积分别达到了371.6 m2/g和0.34 cm3/g,对应的碘和亚甲基蓝吸附值分别是580 mg/g和90 mg/g。同时揭示了活化反应中活化剂首先与炭化料的H、O官能团发生反应形成初级孔隙,进而和C物种反应形成石墨微晶的堆垛和层错,形成多孔结构。

     

    Abstract: Spirit lees was carbonized and then activated by steam and CO2 to prepare activated carbons. The effect of carbonization temperature, type and amount of activator, activation temperature and time on the pore structure, and the adsorption of methylene blue and iodine were investigated. The gas products during activation were analyzed online to reveal the activation mechanism. Results showed that steam activation was rather more active than CO2. Regardless of the activation agent, a low carbonization temperature of 450 ℃ and a medium activation temperature of 800 ℃ favored the iodine adsorption. For the methylene blue adsorption, the same low carbonization temperature of 450 ℃, however, medium/high activation temperatures (850 to 900 ℃) are favorable.. The best activated carbon was prepared with a steam activator using a carbonization temperature of 450℃ and an activation temperature of 800 ℃, which had a surface area and pore volume of 371.6 m2/g and 0.34 cm3/g, and iodine and methylene blue adsorption capacities of 580 mg/g and 90 mg/g respectively. O- and H-containing functional groups in the carbonized spirit lees reacted with the activation regent (steam or CO2) to form the initial pores, then the accessible active sites reacted with the activation regent to generate secondary pores.

     

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