不同热解温度下落叶松半焦特性的演变规律

Effect of pyrolysis temperature on characteristics evolution of larch char

为探究热解温度对生物质半焦特性的影响规律,文章以落叶松为原料,采用管式电阻炉制取200~1000℃的热解半焦,利用元素分析、XRD、BET、SEM等测试手段,结合碳-氢-氧相图及Scherrer方程,深入分析了热解温度对生物焦元素组成、石墨化程度、孔隙结构及表观形貌的影响。结果表明:热解温度升高,热解半焦的H/C,O/C原子比减小,芳构化程度加深,碳微晶结构更趋于有序化,片层状碳骨架结构逐渐凸显,石墨化程度增加;400℃下的半焦比表面积最高,微孔对比表面积的贡献大;300℃和500℃是热解半焦结构发生明显变化的两个特殊的温度点。

Larch was selected as a representative of forestry biomass to study the effect of pyrolysis temperature on characteristics evolution of biochar. Larch samples were treated under the temperature range of 200~1 000 ℃ in the pipe resistance furnace. Analysis methods including ultimate analysis, XRD, BET and SEM combined with carbon-hydrogen-oxygen ternary and Scherrer equation were conducted to characterize the element composition, the degree of graphenation, porosity structure and morphology of larch and biochars. The results showed that the H/C and O/C atomic ratio decreased while the structure of biochars becoming further aromatization, orderliness and graphenation with the emerging of the lamellar carbon skeleton structure. Micropore is a great contributor to the specific surface of biochars, and the specific surface reached its maximum at 400 ℃, 300 ℃ and 500 ℃ are two special pyrolysis temperature points where the structural characteristics of biochars change significantly.