Scale-up of immobilized amine sorbent pellets for landfill gas upgrading, using benchtop and pilot equipment

Abstract

Upgrading CO2/CH4 enriched biogas effluents, especially from landfills, is a viable route towards simultaneously generating renewable methane for energy production and purified carbon dioxide for industries like oil and gas, whose main use is enhanced oil recovery. Pelletized basic immobilized amine sorbents (BIAS) previously utilized for post-combustion CO2 capture are prime candidates for CO2 removal from landfill gas (inherent CH4 enrichment) because of the pellets' high CO2 selectivity and tunability for optimized performance at different temperatures and gas compositions. This work examines the process parameters and material properties that are key in the production scale-up of our previously developed polychloroprene latex-polyethylenimine (PEI, MW = 25,000) binder/silica-fly ash pellet supports. Thicker pastes with aqueous binder solution/powder ratios between 2.9/1 and 3.24/1 exhibited average storage moduli of G' ≥ 9.5 × 106 ± 1.2 × 105 Pa and were easily prepared then transformed into separable cylindrical ropes via a lab-scale mixer-extruder machine. The dried supports displayed good crush strength and a > 98% efficient amine impregnation. Pellets containing 32 wt% PEI800/N-N-diglycidyl-4-glycidyloxyaniline crosslinker (1/0.13 wt. ratio) showed a high 1.95 mmol CO2/g capture from simulated landfill gas (60% CO2/39% CH4/1% O2) at 75 °C that dropped <30% after 24 h at 105 °C under the same gas environment. Scalability of the material was demonstrated by producing a 3.3 kg batch of pellet supports with pilot-scale mixer and extruder equipment. Similar strength and CO2 capture performance for the PEI-functionalized commercial pellets as those for the lab-scale pellets strongly indicate the viability of these materials for pilot-scale landfill gas CO2 capture/upgrading.