Nonisothermal catalytic liquefaction of corn stalk in subcritical and supercritical water
Nonisothermal catalytic liquefaction of corn stalk in subcritical and supercritical water
复制标题
DOI：
10.1021/ef0300141
复制
发表时间：
2004
期刊：
影响因子：
5.3
通讯作者：
C. Song;Haoquan Hu;Shengwei Zhu;Gang Wang;Guohua Chen
中科院分区：
文献类型：
--
作者：
C. Song;Haoquan Hu;Shengwei Zhu;Gang Wang;Guohua Chen
采用热重法（TG）对玉米秸秆进行热解，在碳酸钠（na2co3）和碳酸钠（na2co3）催化和不催化条件下，采用非等温流体萃取技术对玉米秸秆进行半连续液化研究。结果表明，在DTG曲线上，玉米秸秆的主要热解区域为~ 500 ~ 650 K，最大热解速率出现在~ 600 K。催化剂的存在对热解有明显的影响，特别是在550-650 K的温度范围内。当催化剂的添加量大于1.0 wt %时，催化剂的DTG曲线从双峰变为单峰，对半纤维素的影响大于对纤维素和木质素的影响。动力学分析表明，催化剂添加量不同，主要热解范围（10 ~ 70 wt %）的活化能也不同。以3ml /min的水为溶剂，在25mpa压力下，添加或不添加1.0 wt %的na2co3，玉米秸秆的液化转化率分别可达95.7%和95.4%。催化剂的主要作用是提高生物油的收率，从没有催化剂的33.4%提高到1.0 wt % na2co3的47.2%。催化剂对较高温度下的液化有积极作用，可以提高液产物收率，改善液产物质量。与不使用催化剂相比，使用催化剂可以获得更多的生物油和更少的生物气。在实验条件下，玉米秸秆的热解和液化都可能发生两段主反应。
The pyrolysis of corn stalk was performed with thermogravimetry (TG), and its liquefaction was investigated in a semicontinuous apparatus with a nonisothermal fluid extraction technique, both with and without sodium carbonate (Na 2 CO 3 ) as a catalyst. The results indicated that the main pyrolysis region of corn stalk is ∼500-650 K and the maximum rate occurs at ∼600 K on the differential thermogravimetry (DTG) curve. The presence of a catalyst has an obvious effect on the pyrolysis, especially in the temperature range of 550-650 K. When more than 1.0 wt % of catalyst was added, the DTG curve is altered greatly, from two peaks to one, for the catalyst, which has a greater effect on hemicellulose than on cellulose and lignin. Kinetic analysis shows that the activation energy in the main pyrolysis range (10-70 wt %) varies with different amounts of catalyst addition. The liquefaction conversion of corn stalk with 3 mL/min of water as a solvent at a pressure of 25 MPa, with or without the addition of 1.0 wt % of Na 2 CO 3 , is up to 95.7 and 95.4 wt %, respectively. The catalyst mainly improved the yield of bio-oil, from 33.4% without a catalyst, increasing to 47.2% with 1.0 wt % of Na 2 CO 3 . The catalyst has a positive effect on the liquefaction at relatively higher temperatures and can increase the yield of liquid product, as well as improve the quality of liquid product. More bio-oil and less gas can be obtained with a catalyst than that without a catalyst. A two-stage main reaction may occur for both the pyrolysis and liquefaction of corn stalk under the experimental conditions.