328 / 2018-07-28 22:11:28

Catalytic pyrolysis of lignin with red mud derived hierarchical porous catalyst for alkyl-phenols and hydrocarbons production

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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). Based on the changes of the catalyst characteristics and the bio-oil composition, 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.