Abstract Red mud (RM) was activated by a feasible digestion-precipitation method followed by calcination at 600 °C (denoted as ACRM), which was used as a novel catalyst during the thermal degradation of the lignin. The prepared catalyst was then applied to the lignin derived from agricultural waste using a vertical fixed-bed microreactor between 350–650 °C. The texture characteristics of the activated RM were characterized by XRF, FTIR, XRD, TEM, SEM-EDS, NH3-TPD, and the N2 isothermal absorption method. The analysis results indicated that the ACRM catalyst possessed a high specific surface area, hierarchical porosity, acidity and active metal oxides (Fe2O3, Al2O3, and TiO2). Maximum bio-oil yield (25 wt.%) was observed at 550 °C, however, the bio-oil yield exhibited an overall declined trend in comparison to the non-catalytic pyrolysis at the corresponding pyrolysis temperatures. The relative contents of alkyl-phenols and the hydrocarbons significantly increased using the ACRM catalyst at 550 °C, which was attributed to the strengthening of dehydroxylation, demethylation, demethoxylation, and alkylation reactions. The study demonstrated the ACRM could be used as a promising catalyst for upgrading the pyrolysis vapours of lignin with considerable economic and ecological benefits.

中文翻译：

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用赤泥衍生的分级多孔催化剂催化热解木质素用于烷基酚和烃类生产

摘要 赤泥 (RM) 通过一种可行的消化沉淀法活化，然后在 600 °C 下煅烧（表示为 ACRM），在木质素热降解过程中用作新型催化剂。然后使用立式固定床微反应器在 350-650 °C 之间将制备的催化剂应用于源自农业废物的木质素。通过XRF、FTIR、XRD、TEM、SEM-EDS、NH3-TPD和N2等温吸收法对活化RM的织构特性进行表征。分析结果表明，ACRM 催化剂具有高比表面积、分级孔隙率、酸性和活性金属氧化物（Fe2O3、Al2O3 和 TiO2）。在 550 °C 时观察到最大生物油产量 (25 wt.%)，然而，在相应的热解温度下，与非催化热解相比，生物油产量总体呈下降趋势。使用ACRM催化剂在550°C时烷基酚和烃的相对含量显着增加，这归因于脱羟基、脱甲基、脱甲氧基和烷基化反应的加强。该研究表明，ACRM 可作为一种有前景的催化剂，用于提升木质素的热解蒸汽，具有可观的经济和生态效益。