【作者】 李密；

【导师】 刘守新；

【作者基本信息】 东北林业大学 ， 林产化学加工工程， 2009， 硕士

【摘要】 以制材剩余物杨木锯屑等为原料,采用KOH和H₃PO₄为活化剂,化学活化分别制备微孔和中孔活性炭吸附材料。文中系统研究了原料性质对活性炭比表面积和得率的影响;考察浸渍比、活化温度和活化时间等不同的工艺条件对活性炭的比表面积、孔结构和吸附性能的影响;对相应活化机理进行了初步研究。研究的主要内容有:1.对原料组成进行分析,考查研究木质原料的组成成分对活性炭比表面积及吸附性能的具体影响关系。结果发现以浸提落叶松为原料制得活性炭的得率最高,为22.82%;以落叶松为原料制得活性炭灰分最高,为10.7%。KOH与原料浸渍比为4:1,700℃活化1h时,木质素含量是活性炭比表面积大小的主要影响因素。木质素含量越高,得率越大,但所制得的活性炭比表面积越小,且碘值相应减小。2.采用KOH化学活化法制备微孔活性炭。研究发现KOH和锯屑最优活化条件是:浸渍比为1:1,活化时间为60min,活化温度为700℃。北方杨木锯屑制备的活性炭比表面积可达到1748.82m²/g,碘值达到1147.88mg/g,得率最高可达13.08%。样品的平均孔容为0.562cm³/g,孔容最大值对应的孔宽为4.17（?）,平均孔径23.43（?）,微孔率达70%。3.采用H₃PO₄活化制备中孔活性炭。研究发现磷酸活化最佳活化条件是:浸渍比1:2左右,活化温度400～500℃,活化时间60～90 min。以杨木锯屑为原料制得的中孔活性炭比表面积可达1609.43 m²/g,亚甲基蓝吸附值192.45 mg/g,焦糖脱色率可达118%,VB₁₂吸附值可达73.46mg/g。样品BJH脱附孔容为1.72 cm³/g,平均孔径为38.69（?）,SF最高孔径为28.05（?）,中孔率达60%。4.以杨木锯屑为原料的酸碱活化机理分析。KOH活化反应在相对较高的温度下进行,一般高于700℃。活化的主要产物是K₂CO₃,当浸渍比增大时,产物中的KOH含量明显升高。磷酸活化反应在较低分温度下就已经产生,450℃之前磷酸与纤维素不断产生酯类化合物。活化温度在400～450℃比较适宜中孔的形成,温度高于550℃之后中孔显著下降。更多还原

【Abstract】 In this dissertation, the sawdust of poplar etc. from the remainder of wood manufacture in North area was activated separately by KOH and H₃PO₄ to obtain mesoporous and microporous activated carbon （AC） with superior adsorption property. The effect of the compositions of these raw materials on the yield, specific surface area, adsorption values and ash of AC were systematically investigated. The effect of activation conditions, such as ratio, activation time and activation temperature which are controlled, on the specific-surface-area （SSA）, pore structure and adsorption values was investigated to obtain the optimal activation condition. And the activation mechanism was simply researched accordingly in this paper. The main researches and achievements are comprised of the following aspects:1. The effect of the compositions of those raw materials on the yield, specific surface area, adsorption values and ash of AC were investigated. The yield and ash of the AC obtained from the extracted larch and the larch are 22.8% and 10.7%, respectively. The result showed that at the same condition as the ratio of KOH to sawdust 4:1, temperature 700℃and retention time 1 hour, the content of lignin was the most important factor for the specific surface area. The higher lignin content is, the smaller specific surface area is but the yields vary contrarily in the wood material. The effect on the yield of the ash contents in the material is less than the lignin contents.2. Microporous carbon was obtained through the activation of KOH. The optimal activation condition was ratio 1:1, activation time 60 min, and activation temperature 700℃. The activated carbon from poplar sawdust possesses specific surface area of 1748.82m²/g, the iodine adsorption value of 1147.88mg/g and the yield of 13.08%. The average pore volume and diameter were 0.562cm³/g and 23.43 A. The width of pore relating to highest pore volume distribution was 4.17 A. The proportion of micropores was about 70%.3. Mesoporous carbon was obtained through the activation of H₃PO₄. The optimal activation condition was ratio around 1:2, activation time 60 to 90 min, and activation temperature 400℃to 500℃. The activated carbon from poplar sawdust possesses specific surface area of 1609.43 m²/g, the methylene adsorption value of 192.45 mg/g, caramel decoloring value of 118 %, VB₁₂ adsorption value of 73.46mg/g. The BJH Method Cumulative Desorption Pore Volume was 1.72 cm³/g. The average pore diameter was 38.69A. The result of SF Method Pore Diameter was 28.05A. The proportion of mesopores was about 60%. 4. The activation process and mechanism activated by KOH and H₃PO₄ were analyzed and concerned respectively. The activation process activated by KOH took place at a relatively high temperature about 600℃. The main productions in the activated carbon of activation processes were K₂CO₃ and KOH, and the proportion of KOH was enhanced obviously with the increase of ration. The activation process activated by H₃PO₄ took place from room temperature. Before 450℃, phosphate esters were formed as the impregnation of phosphate acid. The ideal activation temperature of mesoporous carbon was produced between 400℃to 500℃. The mesopores were destroyed and decreased sharply at more than 550℃.更多还原