Acid-treated waste red mud as an efficient catalyst for catalytic fast copyrolysis of lignin and polyproylene and ozone-catalytic conversion of toluene

摘要

In this study, red mud (RM), a highly alkaline waste generated from alumina production industries, was used as a catalytic material for both fast copyrolysis of organosolv lignin (OL) and polypropylene (PP) and toluene removal under ozone at room temperature. The RM was pretreated with HC1 to investigate the effect of alkalinity. In the catalytic fast copyrolysis of the OL and PP, the acid-treated RM (HRM) produced more aromatics, phenolics, and light oleflns (C_3 to C_5) but less oxygenates and heavy olefins (C_6 to C_(46)) than the RM. The difference in pyrolytic performance between the RM and HRM was likely attributed to the concentrated Fe_2O_3 species in the HRM catalyst. In addition, more efficient toluene removal was observed over MnO_x/HRM than over MnO_x/RM owing to the large Brunauer-Emmett-Teller surface area, high amounts of Al and Fe, and optimal Mn~(3-)/Mn~(4-) ratio. This study demonstrates that the RM, an industrial waste, can be reused as an effective catalytic material for not only biofuel production but also pollutant removal.