Sorption-enhanced gasification of municipal solid waste in an updraft gasifier utilizing limestone for dual activity as a catalyst and CO2 adsorbent

Rising atmospheric CO2 concentrations have detrimental effects on both the environment and human life, creating a need for sustainable solutions. Municipal solid waste (MSW) can generate low-carbon energy through gasification while mitigating landfill issues related to its disposal. This study examines the dual role of naturally available limestone as a CaO-based CO2 sorbent and catalyst during MSW gasification in a lab-scale updraft gasifier. The effect of limestone/MSW ratio (0-0.20 wt/wt) on product gas composition, heating values, gas yield, carbon conversion, and cold gas efficiencies was invistigated. The fresh and calcined limestone catalysts were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and scanning electron microscopy (SEM). An optimum equivalence ratio (ER) value of 0.30 in air gasification was used. The material and energy balances provided deeper insight into the gasification process. Adding limestone reduced the CO2 concentration from 9 to 1.17 vol%. Similarly, H2 increased to 8.53 vol% and CO to 12.92 vol%. The results demonstrated that a limestone/MSW ratio of 0.20 (wt/wt) significantly improved syngas production, achieving a carbon conversion efficiency of 27.41%, a gas yield of 1.46 Nm3/kg, and a lower heating value of 2.76 MJ/Nm3. This comparative study highlighted the potential of MSW as a feedstock, combined with the use of natural CaO sources, in gasification technology. The study also provides a baseline for commercial enterprises to explore the potential of MSW for syngas production and the utilization of limestone for CO2 capture, contributing to the development of carbon-neutral fuels.