Evaluation of the thermal and environmental stability of switchgrass biochars by Py-GC-MS.
Evaluation of the thermal and environmental stability of switchgrass biochars by Py-GC-MS.
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DOI：
10.1016/j.jaap.2014.09.010
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发表时间：
2014-11
影响因子：
6
通讯作者：
R. Conti;A. Rombolà;A. Modelli;C. Torri;D. Fabbri
中科院分区：
文献类型：
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作者：
R. Conti;A. Rombolà;A. Modelli;C. Torri;D. Fabbri
将快速热解GC-MS（Py-GC-MS）应用于在不同温度（400-700 °C）和停留时间（1-20分钟）下用实验室规模反应器由柳枝稷合成的35种生物炭的表征。Py-GC-MS数据与氢碳摩尔比（H/C）作为炭化强度的指标沿着与其他参数进行了比较。O/C比和生物炭产量与H/C比呈正相关，而灰分、总碳和pH呈负相关。多环芳烃（PAH）浓度与H/C呈弱负相关。热解产物的种类和强度随H/C比的降低而降低，因此，高度炭化生物炭（H/C < 0.4）的热解产物主要是苯、吡咯、甲苯、C2-苯、苯甲腈、苯并呋喃、萘、联苯和菲。这些化合物被认为是高度碳化但热不稳定的生物炭部分的代表。它们相对于代表弱炭化木质纤维素的热解产物的相对丰度（%炭化）与H/C线性相关（R=-0.93）。发现特定的热解产物比和H/C比之间有很好的相关性。四个选定的生物炭与土壤混合，并进行短期呼吸速率实验（220天）。具有中等（H/C = 0.6）和高（H/C = 0.4）碳化度的生物炭产生不同的热解图，但表现出相同的降解速率，其中转化为CO2的转化率比以热解产物中高比例的半纤维素/纤维素标记物为特征的弱碳化样品（H/C = 1.5）低得多。
Flash pyrolysis GC–MS (Py–GC–MS) was applied to the characterisation of 35 biochars synthesised from switchgrass with a bench scale reactor at different temperatures (400–700 °C) and residence times (1–20 min). Py–GC–MS data were compared with the molar hydrogen to carbon ratios (H/C) taken as an index of the charring intensity along with other parameters. O/C ratios and biochar yields were directly correlated with H/C ratios, while ash, total carbon and pH were inversely correlated. A weak inverse correlation was found between polycyclic aromatic hydrocarbon (PAH) concentrations and H/C. The intensity and variety of pyrolysis products in the pyrograms decreased with decreasing H/C ratios, so that pyrograms of highly carbonised biochars (H/C < 0.4) were principally characterised by benzene, pyrrole, toluene, C2–benzenes, benzonitrile, benzofuran, naphthalene, diphenyl, phenanthrene. These compounds were taken as representative of a highly carbonised, but thermally labile portion of biochar. Their relative abundance (% charred) with respect to pyrolysis products representative of weakly charred lignocelluloses was linearly correlated with H/C (R= −0.93). Good correlations were found between specific pyrolysis product ratios and H/C ratios. Four selected biochars were mixed with soil and subjected to short respiration rate experiments (220 days). Biochars with a moderate (H/C ∼ 0.6) and high (H/C ∼ 0.4) degree of carbonisation produced different pyrograms, but exhibited the same degradation rates, with a much lower conversion into CO2than the weakly carbonised sample (H/C ∼ 1.5) characterised by a high proportion of hemicellulose/cellulose markers in the pyrolysate.