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Exploring large pore size alumina and silica-alumina based catalysts for decomposition of lignin

机译：探索大孔径氧化铝和二氧化硅-氧化铝基催化剂分解木质素

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Evaluation of copper doped silica-alumina and γ-alumina catalysts for lignin decomposition was conducted using a suite of chemical analysis protocols that enabled a comprehensive characterization of the reaction product. X-ray diffraction analysis was used to verify the concentration of doped copper on catalyst supports. Then, batch experiments were performed to study the significance of catalyst support type, catalyst dopant concentration, lignin concentration, catalyst-to-lignin ratio, reactor stirring rate and reaction time. Aqueous products were extracted with dichloromethane and analyzed using a detailed gas chromatography-mass spectrophotometry analytical protocol, allowing for quantification of over 20 compounds. Solid residues were analyzed by thermogravimetric analysis and scanning electron microscopy. The highest yield of monomeric products from these screening experiments occurred with 5 wt% Cu on silica-alumina with a 1:1 w/w ratio of catalyst to lignin. A second set of experiments were conducted at these conditions to evaluate the effect of varying the reaction temperature between 300 and 350 oC. Lower reaction temperatures (300 oC) resulted in more unreacted lignin while higher temperatures (350 oC) led to an increased formation of liquid phase products, but also increased char formation. While the total amount of liquid phase products increased, the combined yield of monomer phenolic products was only 5–7 wt% of the liquid extracted product and statistically independent of temperature and other operational parameters, although the yields of different chemicals varied with temperature. Unlike most pyrolytic processes, the concentration of gas phase products gradually decreased with increasing reaction temperature and became negligible at 400 oC, while the formation of coke increased with temperature. This seemingly contradictory result is likely due to increased product polymerization occurring at higher temperatures.
机译：使用一套能够全面表征反应产物的化学分析方案，对铜掺杂的二氧化硅-氧化铝和γ-氧化铝催化剂对木质素的分解进行了评估。 X射线衍射分析用于验证催化剂载体上掺杂铜的浓度。然后，进行分批实验以研究催化剂载体类型，催化剂掺杂剂浓度，木质素浓度，催化剂与木质素的比率，反应器搅拌速率和反应时间的意义。用二氯甲烷萃取水产品，并使用详细的气相色谱-质谱法分析规程进行分析，可定量分析20多种化合物。通过热重分析和扫描电子显微镜分析固体残留物。这些筛选实验中单体产物的最高收率是在催化剂-木质素上以1：1 w / w的比例在二氧化硅-氧化铝上含5 wt％的铜时发生的。在这些条件下进行了第二组实验，以评估在300至350 oC之间改变反应温度的效果。较低的反应温度（300 oC）导致更多的未反应木质素，而较高的温度（> 350 oC）导致液相产物形成增加，但焦炭形成增加。尽管液相产物的总量增加了，但单体酚类产物的总收率仅为液体提取产物的5–7 wt％，尽管不同化学品的收率随温度而变化，但统计学上与温度和其他操作参数无关。与大多数热解过程不同，气相产物的浓度随着反应温度的升高而逐渐降低，在400 oC时可忽略不计，而焦炭的形成随温度升高而增加。这种看似矛盾的结果可能是由于在较高温度下发生的产物聚合反应增加。

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