Catalytic Pyrolysis of Cellulose Using Formulated Red Mud, Sand, and HZSM-5

The catalytic pyrolysis of microcrystalline cellulose (CE) using formulated red mud (FRM) and HZSM-5 catalysts was conducted in a fluidized bed reactor at 400 °C. Both catalysts promoted the conversion of CE. The FRM promoted the formation of organic liquids and pyrolytic water, while the HZSM-5 catalyst promoted the pyrolytic water and the formation of pyrolysis noncondensable gases (PNCGs). The electrostatic precipitator (ESP) biooil (25.8 ± 2.54 wt %) from the CE-FRM consisted mainly of levoglucosan (LGA, 68.60 area %), cyclic ketones (CKs, 2.91 area%), and aromatics (1.38 area%), whereas the HZSM-5 biooil consisted of levoglucosan (82.27 area%). The major oxides of the FRM (i.e., Al2O3 and Fe2O3) were used during the pyrolysis of CE. Both catalysts promoted the formation of pyrolytic water and PNCGs. Compared to sand, the Fe2O3 promoted the formation of anhydrous sugars by about 6%, aromatics by more than 3-fold and CKs by more than 2-fold, whereas the Al2O3 promoted the formation of noncyclic oxygenates (NCOs) by more than 3-fold, furans by more than 3-fold, CKs by more than 5-fold, and aromatics by more than 28-fold. During the CE-FRM pyrolysis, larger particle size resulted in higher char/coke and pyrolytic water yields and lower organic liquid and PNCGs. This was due to the longer residence time of LGA in the larger particles where further dehydration and charring occur. The pyrolysis of d-glucose (DG) over the FRM catalyst resulted in higher char/coke and water yields and lower organic liquid and PNCGs compared to the catalytic pyrolysis of CE over FRM. Compared to the CE-FRM biooil, the DG-FRM biooil had higher furans content and lower yields of anhydrous sugars and aromatics. The longer residence time of LGA produced during the DG-FRM pyrolysis in the hot zone resulted in its further dehydration and polymerization to form char.