Effect of liquefaction parameters of cornstalk cellulose in sub-supercritical methanol on dominant chemical products
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摘要: 在反应温度240-320 ℃、甲醇用量0-200 mL、反应时间0-200 min的条件下，采用间歇式高温高压反应釜对玉米秸秆纤维素在亚/超临界甲醇中进行液化实验，结合GC-MS分析，研究不同液化反应条件下，生物油中轻油、重油产率及液化产物中烃类、醇类、酯类、酸类等主要化合物的组分分布及其变化规律。结果表明，反应温度和甲醇用量对化合物的分布与含量影响较大，反应温度和甲醇用量增加，促进纤维素向烃类、醇类、酯类转化，各化合物含量随之增加，并使轻油、重油产率升高，当反应条件为：甲醇用量160 mL，温度320 ℃，反应时间30 min时，生物油产率达到最高25.1%。生物油中组分含量顺序为：烃类>醇类>酯类>酸类，各化合物最高相对含量分别为77.2%、19.0%、30.9%、20.8%。初步分析发现，随着温度的升高和甲醇量的增加，自由基活性逐渐增强，当甲醇用量超过160 mL、温度超过300 ℃时，醇类以及酯类等化合物进一步发生氧化、缩合等反应形成酸类等化合物，造成化合物产率减小，进而使生物油产率降低。Abstract: The direct liquefaction of cornstalk cellulose in sub-supercritical methanol using an autoclave was investigated under reaction temperature range of 240-320℃, methanol dosage range of 0-200 mL and reaction time range of 0-200 min. The effects of various liquefaction parameters on the yields of bio-oil and dominant components (alkanes, esters, acids and alcohols, etc.) obtained from cornstalk cellulose liquefaction were investigated combining with GC/MS. The results show that the cellulose is transformed to alkanes, esters and alcohols, and the increasing of reaction temperature and methanol dosage can result in an increase in the yields of water soluble organic matter, heavy oil and various chemicals. The yield of bio-oil reaches to 25.1% under the optimum operating conditions:methanol dosage is 160 mL; reaction temperature is 320℃; reaction time is 30 min. The relative contents of dominant components in bio-oil are in the order:alkanes > alcohols > esters > acids, with the highest relative contents of 77.2%, 19.0%, 30.9%, 20.8%, respectively. The reaction temperature and methanol dosage have an obvious influence on the distribution and yields of dominant chemicals. As the reaction temperature and methanol dosage further increases, the concentration and activity of free radical will increase, and the components of alcohols and esters can be oxidized and condensed to transform into acids and so on when the reaction temperature and methanol usage are more than 160 mL and 300℃, respectively, leading to a decline in the yields of chemicals and bio-oil.
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Key words:
- stalk cellulose /
- methanol /
- reaction temperature /
- reaction time
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图 1 甲醇用量对轻油、重油和生物油产率的影响
Figure 1 Effect of methanol dosage on the yield of water soluble organic matter, heavy oil and bio-oil
图 2 反应温度对轻油、重油和生物油产率的影响
Figure 2 Effect of reaction temperature on the yield of water soluble organic matter, heavy oil and bio-oil
图 3 反应时间对轻油、重油与生物油产率的影响
Figure 3 Effect of reaction time on the yield of water soluble organic matter, heavy oil and bio-oil
图 4 甲醇用量对轻油中主要化合物相对含量的影响
Figure 4 Effect of methanol dosage on the relative contents of dominant components in water soluble organic matter
图 5 甲醇用量对重油中主要化合物相对含量的影响
Figure 5 Effect of methanol dosage on the relative contents of dominant components in heavy oil
图 6 反应温度对轻油中主要化合物相对含量的影响
Figure 6 Effect of reaction temperature on the relative contents of dominant components in water soluble organic matter
图 7 反应温度对重油中主要化合物相对含量的影响
Figure 7 Effect of reaction temperature on the relative contents of dominant components in heavy oil
图 8 反应时间对轻油中主要化合物相对含量的影响
Figure 8 Effect of reaction time on the relative contents of dominant components in water soluble organic
图 9 反应时间对重油中主要化合物相对含量的影响
Figure 9 Effect of reaction time on the relative contents of dominant components in heavy oil
表 1 玉米秸秆纤维素在不同甲醇用量中液化生成轻油中主要化合物的GC-MS分析
Table 1 GC-MS analysis for dominant chemicals of WSO with various dosages of methanol
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