Influence of the Carbonization Process on Activated Carbon Properties from Lignin and Lignin-Rich Biomasses
Influence of the Carbonization Process on Activated Carbon Properties from Lignin and Lignin-Rich Biomasses
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DOI：
10.1021/acssuschemeng.7b01895
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发表时间：
2017-09-01
影响因子：
8.4
通讯作者：
Kruse, Andrea
中科院分区：
文献类型：
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作者：
Correa, Catalina Rodriguez;Stollovsky, Moritz;Kruse, Andrea
测试了富含木质素的生物质（山毛榉木、松树皮和橡树皮）和四种木质素作为前体，通过用 KOH 进行两步化学活化来生产活性炭 (AC)。首先，通过热解或水热碳化对前体进行碳化，目的是评估碳化过程对活性炭性能的影响。热解炭（pyrochars）比水热碳化炭（Hydrochars）热稳定；因此，从焦炭中产生了更多的活性炭（活性炭产量根据焦炭量计算）。就根据生物质或木质素的初始量计算的 AC 产量而言，来自水热炭和火热炭的 AC 之间的差异很小。此外，两种活性炭之间的总表面积和表面化学性质没有发现显着差异。为了理解这一点，活化机制被解释为局部碱催化气化。就氢炭而言，由于其热稳定性较低，碳化反应与气化同时发生。因此，水热炭活性炭的碳含量和产率与火热炭活性炭相似，但其微孔表面积较低，这可能是由于挥发性物质的冷凝所致。
Lignin-rich biomass (beech wood, pine bark, and oak bark) and four lignins were tested as precursors to produce activated carbon (AC) via a two-step chemical activation with KOH. First, the precursors were carbonized via either pyrolysis or hydrothermal carbonization, with the purpose of evaluating the influence of the carbonization process on the AC properties. Pyrolysis chars (pyrochars) were thermally more stable than hydrothermal carbonization chars (hydrochars); thus, more AC was yielded from pyrochars (AC yield calculated from the char amount). The difference between ACs from hydrochars and pyrochars was small regarding the AC yield calculated from the initial amount of biomass or lignin. Additionally, no considerable differences in terms of total surface area and surface chemistry were found between both ACs. To understand this, the mechanism of the activation was explained as a local alkali-catalyzed gasification. In the case of hydrochar, carbonization reactions occurred simultaneously to the gasification because of their lower thermal stability. Thus, the carbon content and yields of hydrochar ACs were similar to pyrochar ACs, but their microporous surface areas were lower, likely due to condensation of volatile matter.