Flat sheet membrane contactor (FSMC) for CO2 separation using aqueous amine solutions

A new multi-flat-sheet membrane contactor (FSMC) was developed and used to investigate CO2 removal from CO2/N2 gas mixture using aqueous 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) solution in the presence and the absence of piperazine (Pz) as activator. The FSMC was operated under various experimental conditions in order to study the effect of liquid flow rate, gas phase composition, CO2 liquid loading and contactor configuration (number of membranes, type of membrane (PTFE, PP and laminated PTFE/PP) and fluid flow orientation (co- and counter-current)). For comparison purpose, MEA aqueous solution (the benchmark amine used in the CO2 capture process) was also tested under the same experimental conditions. The absorption rates through the membranes were found to increase with the increase of liquid flow rate and CO2 concentration in the gas phase and decrease with the raise of CO2 loading. Pz activated AHPD solution showed better performance than single AHPD solution, and similar absorption fluxes were obtained for AHPD+Pz and MEA solutions. As a proportional increase of the absorption rate with the number of membranes was observed, when required, more membranes can be easily added to a contactor module to increase the absorption performance. A two-scale model accounting for CO2 diffusion in the gas-filled membrane pores, CO2 and amines diffusion/reaction in the liquid-filled membrane pores and CO2 and amines diffusion/reaction in the liquid boundary layer was developed to describe the comportment of the multi-flat-sheet membrane contactor.