Novel Polymer Membrane Process for Pre-Combustion CO2 Capture from Coal-Fired Syngas

Gasification of coal – a low-cost and abundant domestic feedstock – and subsequent conversion to hydrogen and energy with simultaneous CO2 capture can improve national energy security in an environmentally responsible manner. To fulfill the promise of clean energy production through gasification of domestic coal, more efficient and less costly methods of separating the post-shift syngas (hydrogen and carbon dioxide) are needed. Current absorption technologies (Rectisol, Selexol, and PSA) used for this separation are costly, energy intensive, and unlikely to meet DOE CO2 capture targets.

Membranes of various types are currently being considered for H2/CO2 separations in future IGCC power plants. Key membrane challenges identified from previous work in this area include high membrane cost, low flux, instability in a challenging thermal and chemical environment, device reproducibility, scale-up issues, and poor membrane system design understanding. For an Integrated Gasification Combined Cycle (IGCC) membrane process to be successfully implemented, innovations in the membranes and membrane process designs that address these issues are required.

In this talk, novel high-temperature-stable polymer membranes with H2/CO2 selectivities of >10 and hydrogen permeances of >200 gpu at syngas cleanup temperatures of 100–200°C will be discussed. These membranes can be used in an efficient membrane process that will capture >90% of CO2 in post-shift syngas and generate a hydrogen stream with >93% purity at low cost. Results from a recent field test treating real coal-derived syngas will be presented.

Keywords: syngas, membrane, carbon dioxide, hydrogen and IGCC