采用单因素和正交实验, 考察了沙生灌木沙柳在苯酚和四氢萘混合供氢溶剂中液化的反应时间、反应温度、催化剂用量、苯酚用量和四氢萘用量等工艺参数对液化产物残渣率的影响, 得到沙柳在混合溶剂中的最优化工艺是: 反应温度120℃, 反应时间2 h, 催化剂(98%的浓硫酸)1 mL, 苯酚15 g, 四氢萘5 mL, 此条件下的液化率可达97.51%。各因素影响次序为: 反应温度> 反应时间> 催化剂用量> 四氢萘用量> 苯酚用量。不同反应时间下的沙柳液化液体产物红外谱图表明, 在反应时间30 min 前产生新峰, 在30 min 后谱图特征相同; 固体残渣红外谱图表明, 沙柳组分中的木质素和半纤维素首先发生了降解, 木质素结构单元中的酚醚键断裂先于木质素芳香核之间的碳碳键的断裂, 且液化反应的最终固体残渣中含有吡喃糖环和缔合羟基; 液化固体残渣热重分析表明, 产物中的有机质随液化的进行逐步减少, 且热分解反应分为2 个阶段, 表现出明显的阶段性。
The effects of the reaction time, the reaction temperature, the dosages of catalyst, phenol, and tetralin on the liquefaction ratio of the Salix psammophila with phenol-tetralin as the hydrogen-donor solvents are investigated by orthogonal and single factor tests. The optimal conditions are found as follows: the reaction temperature is 120℃, the time duration is 2 h, the phenol dosage is 15 g, the catalyst (98%H2SO4) dosage is 1 mL, the tetralin dosage is 5 mL. The liquefaction efficiency is 97.51% under these conditions. The order of importance of these factors is: Reaction temperature > reaction time > dosage of catalyst > dosage of tetralin > dosage of phenol. The infrared spectrograms of the liquid products at different reaction times in the liquefaction see new peaks before 30 min and have similar spectrogram characterizations after 30 min. The FTIR of the solid residue indicates that the hemi-cellulose and the lignose are degraded firstly. The fractures of the spatial network structures of the lignin formed by the ether bonds precede those of the carbon-carbon bonds among aromatic nucleus, and the pyranose rings and the hydroxyl bonding groups are contained in the final solid residue of liquefaction. The thermogravimetric analysis of the solid residue suggests that the organic matter in the product is gradually reduced along with the liquefaction. And the pyrolysis reaction shows obvious phases and is divided into two stages.
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