Hybrid membranes to limit amine evaporation in membrane contactors for CO2 capture
Abstract
In order to meet the global demand of energy from combustion processes with fossil fuelswithout interfering with the atmospheric levels of CO2, carbon capture and storage (CCS)is considered a viable solution. Separation of CO2from combustion gas performed byabsorption/stripping in columns is today a costly and energy demanding process. Oneway to reduce the energy requirement of CO2absorption is to use DEEA MAPA blends,but they are volatile and their use at industrial level is thus problematic.Membrane based absorption, defined as membrane contactors allow operating with volatileabsorbents without emitting more harmful chemicals. This require a membrane that allowshigh CO2and low absorbent permeability. Membrane contactors also have thepotential to reduce the capital cost of absorption as effective membrane modules increasethe surface area of absorption, and thereby reduce the process volume.This thesis has investigated two different AF2400 membranes with addition of ZIF-8 andXT-RGO nanoparticles, and in particular how these nanocomposite membranes affectcharacteristics that are important to consider in membrane contactor absorption. Themembranes were tested together with a volatile 3rd generation CO2absorbent named3D3M and with MEA as a reference absorbent. It was discovered that the two nanocompositemembranes decreased the permeability of the two amine absorbents substantiallycompared to the pure AF2400 membrane. However, the nanocomposite membranes alsorevealed a lower CO2 permeability compared to pure AF2400. A simple membrane contactormodel was proposed to evaluate the membrane module performance in terms ofevaporation prevention. Other highly CO2 permeable membranes were tested togetherwith 3D3M and two other 3rd generation absorbents - 3DEA2M and 3HEPP2M, whereonly AF2400 proved to be stable with the absorbents.