【摘要】 利用生物质废料——棕榈壳,采用不同的浸渍方法制备高效活性炭。详细探讨了活化温度和浸渍剂(氢氧化钠)浓度对活性炭性能的影响。采用固定床吸附二氧化硫气体,评价了制备样品的吸附能力。还开展了解吸过程的研究,证明了二氧化硫与活性炭表面之间发生的化学吸附或化学反应。研究表明,采用前期浸渍方法制备活性炭时,原料表面的氢基团被钠置换,形成交联体,从而可获得较高的活性炭收率。而且,这些钠离子在二氧化碳活化阶段还起到催化作用。采用中期浸渍方法,氢氧化钠脱水后生成单质钠,夹杂在碳层中有利于微孔的形成,活化时与二氧化碳生成碳酸钠,可防止试样的过度烧失。采用后期浸渍方法时,由于氢氧化钠颗粒阻挡了活性炭的微孔通道,改变了活性炭的结构特性。但附着的氢氧化钠可通过生成亚硫酸钠,提高对二氧化硫的除去效果。更多还原

【Abstract】 In this paper, preparation and characterization of activated carbon from palm shell, a biomass solid waste, by sodium hydroxide (NaOH) treated at different stages were studied. The effects of activation temperature and impregnant content on the characteristics of the activated carbon were investigated. Fixed-bed adsorption of sulfur dioxide (SO2) gas was carried out to evaluate the adsorptive capacity of the samples. Desorption tests were conducted to verify the occurrence of chemisorption due to some surface functional groups or of chemical reaction between SO2 and NaOH. It was found that pre-impregnation of raw palm shell was involved in replacement of some hydrogen ions with sodium ions to form cross-linked complexes, resulting in a relatively high yield. Moreover, these sodium ions accelerated the reaction as catalysts during gasification of chars by carbon dioxide. For chars with mid-impregnation, sodium hydroxide dehydrated to form metallic sodium, which were intercalated to the carbon matrix and accounted for pore development. Formation of sodium carbonate layers prevented the sample from over burn-off. Post-impregnation of final products would modify the textural characteristics of the sample as some pore entrances were blocked by chemicals. However, sodium hydroxide enhanced the amount of SO2 treated via the formation of sodium sulfite.更多还原