Efficient utilization of high CO2 landfill-gas for syngas generation: Ultra-rich combustion pathways study in porous media reactor via CFD simulation

The current investigation explores the possibility of extracting syngas from low-calorific value landfill-gas rich-combustion with pure O 2 , which contains a considerable amount of CO 2 in its composition as an effective strategy in CO 2 utilization. The results illustrate that enhancement in mixture velocity leads to a notable increment in syngas energy conversion efficiency from 36.9 % to 44.14 %. Furthermore, it was observed that the maximum rate of H 2 production occurs at an equivalence ratio of 2.2, followed by a subsequent decrease until the end of the studied interval. At a mixture velocity of 25 cm/s, CH 4 and CO 2 conversion ratios reach a maximum of 89.02 % and 42.85 %, respectively, alongside the highest syngas production efficiency. Moreover, with an equivalence ratio of 1.6 and a fuel mixture containing 70 % CH 4 , the highest achievable syngas composition was found to be 0.3277 for CO, 0.2841 for H 2 , 0.0676 for CH 4 , and 0.2534 for CO 2 , indicating useful conditions for syngas production. Eventually, reaction pathways analyses revealed that the hydrogen abstraction reactions of hydrocarbon species by H radical which majorly progress through direct CH 4 to H 2 conversion route, and hydrocarbon recombination routes have a key role in H 2 production from landfill gas. Moreover, for landfill gas with high CO 2 content, direct CO 2 to the CO reduction route is determinative. Conversely, when the CH 4 content of landfill gas is high, hydrocarbon recombination followed by ketenyl radical formation and decomposition to CO is the primary pathway in different mixture equivalence ratios. • The feasibility of extracting H 2 -rich syngas from landfill gas is carried out. • Ultra-rich combustion mode is applied to obtain H 2 -rich syngas via porous reactor. • Pure O 2 is utilized as an oxidizer for obtaining high LHV syngas. • Reaction pathways analysis is done to detect the main routes for syngas production. • Hydrogen abstraction of hydrocarbons by H radical has major role in H 2 production.