Biogas upgrading with various single and blended amines solutions: Capacities and kinetics

Biogas is an important renewable energy and biogas upgrading which separate CH4/CO2 to increase the heating value of biogas is necessary for its utilization. Amine scrubbing is a promising biogas upgrading technology. In this study, we applied various single and blended amines solutions for biogas upgrading and reconsidered the evaluation method by comparing the equilibrium CO2 absorption capacity (q(e)) and optimal CO2 absorption capacity under 90 vol% or 95 vol% pure CH4 requirement (q90%CH4, q95%CH4). Three apparent kinetic models and Fourier-transform infrared spectroscopy (FT-IR) were applied to study the kinetics. The results showed that, compared with the qe, the new indicator q90%CH4 and q95%CH4 could better reveal the difference and improvements between various amines solutions and be more accordance with the real situation of biogas upgrading. The q90%CH4 increased from 0.15 to 0.82-1.70 mol/kg after adding other amines with methyldiethanolamine (MDEA), but q(e) was almost the same. For kinetics, the fitting results of Avrami model are the best among the three models. FT-IR analysis before and after absorption showed CO2 formed different groups with different amine molecules. This study provided a new perspective and method on evaluation of amine scrubbing for biogas upgrading, contributing to future research and industrial application. (C) 2022 Elsevier Ltd. All rights reserved.