(656d) Amine-Infused Adsorbents for Biogas Purification to Rng

Biogas is a source of methane that can be used directly as fuel for combustion engines, gas turbines, and fuel cells as a renewable energy source after its purification. Since CO₂ is the major contaminant, supported amines are candidate adsorbents, which have advantages over conventional methods such as scrubbing and pressure swing adsorption (PSA). In the work reported here, the synthesis, characterization, and performance testing of polyethylenimine (PEI) adsorbents will be described. The PEI loading was optimized on hyper-cross-linked polymeric (HCP) resins to achieve nearly 3 mmolCO₂/g adsorbent in the presence of moisture and remained stable across multiple adsorption-desorption cycles. In-situ DRIFTS studies indicated that CO₂ adsorption on PEI-impregnated sorbent aligns with the zwitterion reaction mechanism, and the sorbent could be fully regenerated at 100°C. In addition to the experimental studies, an economic feasibility analysis revealed that PEI-impregnated resin sorbents require lower capital and operating costs compared to conventional biogas upgrading technologies. The role of purification of other minor contaminants will be discussed and results for purification of real biogas (from a Florida landfill) will be presented. Environmental considerations are also part of the effort.