Syngas Components Recovery during Membrane Gas Separation

Abstract

Membrane operations are a promising way of improving and adjusting the composition of the biomass gasification product – syngas – before it can be further transformed into fuels and energy. The presented study focuses on the recovery of individual components (H2, CO, CO2) during membrane separation under varying conditions – pressure difference and the feed composition. Model syngas mixtures with four different compositions containing between 12-24 %mol H2, 34-39 %mol CO and 43-49 %mol CO2 were tested under different pressure differences ranging from 1 to 8 bar (retentate pressure ranging from 2 to 10 bar, permeate pressure from 1 to 4 bar), at temperature 22 °C. Results of the study indicate exponential dependency existence between total pressure drop and the components recovery. The data were approximated with fixed parameter for minimal pressure difference for each component (p0 = 0.5 bar for H2 and p0 = 0.7 bar for CO2) and with variable exponent coefficients. The coefficients in exponent are strongly dependant on permeate pressure (ranging from 0.33 to 0.88 bar-1 for different permeate pressures for CO2 recovery) and vary with feed composition as well (from 0.75 to 0.83 bar-1 across different mixtures for CO2 at fixed permeate pressure).