Valorization of Municipal Solid Wastes and Paper Mill Sludge Through Their Steam Co-Gasification for the Production of Energy Carriers Rich in H2 and Lean in Greenhouse Gas Emissions

Abstract

This study aimed to explore the valorization of municipal solid wastes and paper mill sludge through their steam co-gasification, for the production of energy carriers rich in H₂ and lean in CO₂ greenhouse gas emissions. Waste concrete fines and paper sludge ash were investigated as CO₂ sorbents and Na₂CO₃ as a catalyst. The experiments were carried out in a fixed bed reactor coupled with a thermal analysis-mass spectrometer unit. The analysis encompassed various aspects including the composition of the resulting gas and its heating value, H₂ and syngas yield, fuel conversion and energy recovery, under different operating conditions. When quarry dust was used to capture CO₂ at a calcium-to-carbon molar ratio of unity and 750 °C, H₂ in the product gas was 75.7 mol%, molar ratio H₂/CO was 7.19 and syngas yield was 0.65 m³/kg. When the Na₂CO₃ catalyst was added at a loading of 20%, H₂ in the gas mixture was increased to 81%, the syngas yield to 2.82 m³/kg and conversion of fuel was complete. When paper sludge ash was used as CO₂ sorbent a higher amount of CO₂ was captured, however the selectivity towards H₂ production was lower. The performance of Na₂CO₃ catalyst was better in the presence of quarry dust sorbent.