Chapter 9: Novel Hybrid Membrane/Pressure Swing Adsorption Processes for Gas Separation Applications

Two widely known standalone technologies, such as pressure swing adsorption (PSA) and membrane permeation, have been extensively developed and applied in industry for gas separation. Their process configurations have been widely studied to either minimize recompression work for reducing final operational costs, or to give a better reuse to some waste gases that are not usually recovered by using more conventional methods. Although there is some published work on the development of hybrid systems integrating these two technologies, the awareness for innovative hybrid permeation- and sorption-based processes was seen only recently as an opportunity to further reduce the amount of waste, recover its energy, and recycle as much as possible.

In applications where membranes can provide a moderately pure product at low cost, the separation may actually be inexpensively upgraded by a subsequent process. Likewise, the separation performance of fully established non-permeating technologies can be improved with marginal costs, if one uses truly synergistically hybrid schemes involving membranes. This fact has motivated active research on the integration of membranes with other separation processes, such as PSA. Accordingly, the present chapter intends to show the better of these two technologies in a cooperative mode of operation, rather than in a competitive one. New advances in membrane-based hybrid processes for gas separation and waste reduction via adsorption are examined, and the future prospects for synergistic coupling of separation processes are also suggested. The areas of potential waste reduction focused are natural gas, landfill gas, synthesis gas, hydrogen from reformer off-gas and olefin/paraffin separation.