澳洲坚果壳活性炭制备的热解特性研究

Study on Pyrolysis Characteristics of Macadamia Shell during Preparation of Activated Carbon

以澳洲坚果壳为原料,磷酸为活化剂,利用同步热重-差热分析仪(TG-DTA)对澳洲坚果壳的热失重、热效应以及热解机理进行探讨.实验结果表明:不同条件下的澳洲坚果壳的热分析曲线都有两个失重阶段和相应的吸热峰或放热峰.澳洲坚果壳热解温度在200～410 ℃之间,800 ℃时残余量接近零.以磷酸为活化剂浸渍12和24 h的磷酸-澳洲坚果壳炭化和活化温度区间为130～400 ℃,800 ℃时残余量分别为34.431 %和17.743 %.磷酸-澳洲坚果壳较佳的活化温度在400 ℃左右,浸渍时间选择24 h为宜.同时随着浸渍时间的增加,DTG峰值温度呈现向低温推移的趋势,由未浸渍的363.63 ℃降至为243.71 ℃和238.37 ℃.磷酸浸渍对澳洲坚果壳有明显促进炭化作用,使其在130 ℃左右就开始热解炭化,研究结果为澳洲坚果壳活性炭制备提供理论依据.

Pyrolysis of macadamia (Macadamia ternifolia F.Muell.)shell with phosphoric acid as activating agent to prepare activated carbon was carried out by simultaneous measurements of thermogravimetry(TG) and differential thermal analysis(DTA),so as to study the pyrolysis mechanism of macadamia shell, the enthalpy change and weight loss. According to experimental data, all thermal analysis curves of macadamia shell have two weight loss-stages with related heat-absorption peak or heat-releasing peak under different conditions. Temperature interval of pyrolysis is from 200-[KG-*6] 410℃ ,residue amount is close to zero at 800℃ . Soaked in phosphoric acid for 12 and 24h , respectively, temperature range of charring and activating of phosphoric acid- macadamia shell is from 130-[KG-*6] 410℃ and amounts of residue are 34.431% and 17.743% respectively.The optimum activating temperature is about 400℃ ,soaking time is 24h by phosphorylation. With increasing of soaking time, peak of DTG curve is gradually shifted to lower temperature,descending from 363.63℃ of the unsoaked to 243.71℃ and 238.37℃ of the soaked.Soaking of phosphoric acid enhances charring reaction and phosphoric acid-macadamia shell starts its pyrolysis at 130℃ . The results provide significant theoretical basis in preparation of activated carbon of macadamia shell.