不同热解温度下禾本科植物生物炭理化特性分析

以禾本科植物王草、水稻秸秆、甘蔗渣和玉米秸秆为原料，在厌氧条件下于300、500和700℃制备王草炭（I）、水稻秸秆炭（R）、甘蔗渣炭（S）和玉米秸秆炭（M），研究了不同热解温度对生物炭结构及组成的影响。研究结果表明：随着热解温度升高，4种生物炭产率下降，300℃时I、R、S和M的产率分别为45.81%、48.67%、46.81%和46.00%，而700℃时产率则分别为33.93%、35.47%、25.42%和31.23%；灰分和碳含量升高，700℃时I、R、S和M的灰分较300℃分别提高了54.39%、65.44%、95.54%和71.65%；I、S和M的C/N比随温度升高而升高，R与之相反。4种生物炭pH值随温度升高而升高，700℃时I、R、S和M的pH值分别为7.68、9.87、7.59和9.33，均呈碱性；I和S孔隙结构丰富，随温度升高，孔隙数量增加，而R和M均在700℃形成了一定量的絮状结构；X射线能谱（EDS）分析结果表明R中Si元素含量较高。随温度升高，4种生物炭中烷烃基、甲基（—CH₃）和亚甲基（—CH₂）逐渐消失，生物炭结构以芳香族化合物和含氧官能团为主，结构更稳定。

Physicochemical and Infrared Spectroscopic Properties of Gramineae Plants Biochar at Different Pyrolysis Temperatures

The biochars I, R, S and M were prepared at 300, 500 and 700℃ with the grasses of king grass, rice straw, bagasse and corn straw as raw materials, respectively. The effects of different pyrolysis temperatures on the structure and composition of biochar were studied. Results showed that with pyrolysis temperature increasing, the yield of the four kinds of biochars decreased, carbon content and ash content increased. The yields of I, R, S and M at 300℃ were 45.81%, 48.67%, 46.81% and 46.00%, and the yields at 700℃ were 33.95%, 35.47%, 25.42% and 31.23%. The ash contents and I, R, S and M at 700℃ increased by 54.39%, 65.44%, 95.54% and 71.85% compared those at 300℃. The C/N ratio of R, S, and M were increased with pyrolysis temperature increasing, but that of R was opposite. The pH values of the four biochars increased with pyrolysis temperature increasing. The pH values of I, R, S and M at 700℃ were 7.68, 9.87, 7.59 and 9.33. I and S was porosity and the number of pore increased with the increase of pyrolysis temperature. Both R and M formed a certain amount of flocs at 700℃. EDX analysis revealed that the elemental composition of Si was contained higher in R. Infrared spectroscopy showed that with the increase of pyrolysis temperature, the alkane groups, methyl groups (—CH₃) and methylene groups (—CH₃) of the four kinds of biochars gradually disappear. The biochar structure was dominated by aromatic compounds and oxygen functional groups, and the structure was more stable.