The effect of pyrolysis conditions on biochar stability as determined by three methods
The effect of pyrolysis conditions on biochar stability as determined by three methods
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DOI：
10.1111/gcbb.12030
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发表时间：
2013-03-01
影响因子：
5.6
通讯作者：
Cross, Andrew
中科院分区：
文献类型：
--
作者：
Crombie, Kyle;Masek, Ondrej;Cross, Andrew
生物炭是在氧气有限的环境中通过热化学处理有机材料而产生的多孔含碳材料。一般来说，大多数生物炭可以被认为是耐化学和生物分解的，因此适合于碳（C）封存。然而，为了评估不同类型生物炭的固碳潜力，需要对其稳定性进行可靠的测定。已经提出了几种用于评估生物炭稳定性的技术，例如近似分析、氧（O）：C比和氢（H）：C比;然而，它们中没有一种被广泛认可或验证用于此目的。由三种原料生产的生物炭（松树，稻壳和小麦秸秆）在四个温度下（350、450、550和650摄氏度）和两种加热速率使用三种稳定性测定方法分析（5和100 ℃ Cmin 1）：近似分析，最终分析和一个新的分析工具，在英国生物炭研究中心开发的爱丁堡加速老化工具（爱丁堡稳定性工具）。正如预期的那样，增加热解温度导致更高的馏分稳定C和总C由于挥发物的释放增加。将爱丁堡稳定性工具的数据与通过其他方法获得的数据（即固定碳、挥发物、O：C和H：C比）进行比较，以研究它们之间的潜在关系。比较结果表明，爱丁堡稳定性工具测定的稳定C与固定C、挥发性物质和O：C之间存在较强的相关性（R>0.79），而H：C显示较弱的相关性（R=0.65）。了解原料和生产条件对生物炭长期稳定性的影响对于其作为碳减排措施的作用至关重要，因为不稳定的生物炭的生产和使用将导致碳相对快速地返回大气，从而可能加剧而不是缓解气候变化。
Biochar is the porous, carbonaceous material produced by thermochemical treatment of organic materials in an oxygen-limited environment. In general, most biochar can be considered resistant to chemical and biological decomposition, and therefore suitable for carbon (C) sequestration. However, to assess the C sequestration potential of different types of biochar, a reliable determination of their stability is needed. Several techniques for assessing biochar stability have been proposed, e.g. proximate analysis, oxygen (O): C ratio and hydrogen (H): C ratio; however, none of them are yet widely recognized nor validated for this purpose. Biochar produced from three feedstocks (Pine, Rice husk and Wheat straw) at four temperatures (350, 450, 550 and 650 degrees C) and two heating rates (5 and 100 degrees Cmin1) was analysed using three methods of stability determination: proximate analysis, ultimate analysis and a new analytical tool developed at the UK Biochar Research Centre known as the Edinburgh accelerated ageing tool (Edinburgh stability tool). As expected, increased pyrolysis temperatures resulted in higher fractions of stable C and total C due to an increased release of volatiles. Data from the Edinburgh stability tool were compared with those obtained by the other methods, i.e. fixed C, volatile matter, O:C and H:C ratios, to investigate potential relationships between them. Results of this comparison showed that there was a strong correlation (R>0.79) between the stable C determined by the Edinburgh stability tool and fixed C, volatile matter and O:C, however, H:C showed a weaker correlation (R=0.65). An understanding of the influence of feedstock and production conditions on the long-term stability of biochar is pivotal for its function as a C mitigation measure, as production and use of unstable biochar would result in a relatively rapid return of C into the atmosphere, thus potentially intensifying climate change rather than alleviating it.