Experimental study of a novel biogas upgrading process based on chemical absorption using an AEP-AMP blend for energy efficient CO2 capture

Europe is the major biogas supplier worldwide and considers biogas as a promising renewable energy source to meet its decarbonization target by 2050. An upgrading stage is mandatory to obtain 95 %v/v CH 4 concentrated biomethane that can be used in the industrial sector. The elevated CO 2 content of biogas provides a high driving force for the CO 2 /CH 4 separation that can lead to further energy reduction for biogas upgrading via chemical absorption. In this work, a 10 kg/day CO 2 capture bench-scale plant was used to evaluate the feasibility and performance of a novel AMP/AEP aqueous solvent applied to biogas upgrading. AMP/AEP blends exhibit high stability, low volatility and high CO 2 cyclic capacity over 1 mol CO 2 per mole solvent. MEA was selected as benchmark for further comparison. Two operation modes were tested for the stripping unit: conventional operation at 120 °C and a partial solvent regeneration, namely Shift to Low Temperature (StLT). The novel AMP/AEP solvent provides a flexible operation range that can strengthen the potential of StLT to reduce energy consumption during the regeneration stage. StLT was tested at two stripping temperature levels: 117 °C and 115 °C. The novel solvent exhibited excellent CO 2 absorption performance and required half of solvent flow-rate to achieve the same CO 2 removal as the benchmark. The novel solvent combined with a StLT operation mode at 117 °C as stripping temperature led to 4.50 GJ/t CO 2 specific energy consumption which contributes with 21 % reduction of the energy demand during the regeneration stage compared with the benchmark.