A new strategy: Multi-metal catalysis and structure-oriented role of ash-rich industrial sewage sludge to enhance co-gasification with waste textile

Ash-rich industrial sewage sludge, abundant in mineral metals such as calcium, iron, and potassium, possesses significant catalytic potential. We proposed utilizing this sludge to catalyze waste textiles for efficient co-gasification. This study presented a synergistic reaction mechanism for the CO2 co-gasification of ash-rich industrial sewage sludge and textile waste, integrating isothermal gasification experiments with micro-scale char structure analysis. The co-gasification process was found to reduce the activation energy by 21.57–33.82 kJ/mol and increase the gasification reaction rate by 0.04–0.44 min−1 compared to gasifying textile waste alone. Notably, the synergistic effect was pronounced at carbon conversion rates exceeding 50 %. In addition to exhibiting a polymetallic catalytic effect, ash-rich industrial sewage sludge demonstrated a structure-directing influence on the char produced during co-gasification. The reactive alkali and alkaline earth metals in the sludge modified the waste textile char's structure, facilitating a transition from an ordered to a disordered state. This led to a reduction in the degree of graphitization during char gasification, a decrease in cross-linking structures, an increase in amorphous carbon content, and an enhancement of the number of active sites. These results provide valuable insights into the co-gasification of ash-rich industrial sewage sludge with waste textiles.