Low Carbon Formaldehyde Generation from Chemical Looping Gasification of Heterogeneous Solid Waste

Growing concerns about the environmental impact of traditional solid waste disposal methods like landfilling and incineration have intensified the search for sustainable alternatives. Promising techniques, such as recycling, biological treatment, and gasification, face challenges, such as feedstock variability, tar formation, and char conversion, which hinder their commercial scalability. To address these challenges, the Ohio State University has developed moving bed chemical looping (CL) technology, showing promise in converting various feedstock into high-quality syngas. This research focuses on simulating a co-current chemical looping plastic and biomass to syngas (CL-PBTS) system utilizing municipal solid waste, particularly plastics and lignocellulosic biomass, such as corn cob, to produce high-purity syngas, which can then be used as a valuable feedstock for formaldehyde generation. The process simulations evaluated key thermodynamic parameters, such as syngas quality, solid conversion, carbon emissions, and raw material requirements. The proposed process was experimentally validated on a 2.5 kWth bench-scale reactor. Multiple scenarios were explored for the autothermal operation of the CL system, which shows significant advantages in terms of energy cost, as it does not require any external heat source. The simulation results demonstrate a syngas purity improvement of over 10 percentage points with CL compared to conventional indirect gasification of plastics. Additionally, the CL cases exhibit significantly higher overall exergy efficiency, ranging from 38.8% to 71.5%, compared to the conventional process, which has an efficiency of only 26.19%. These results confirm the practicality of the CL-PBTS process and offer valuable insights into utilizing solid waste at the system level.