(449ai) CMS Membranes for Nitrogen and Sour Gases Purification from Natural Gas

Authors: 
Wang, K., The Petroleum Institute
Khan, S., The Petroleum Institute
Nitrogen and sour gas removal from natural gas is traditionally an energy intensive process, due to similarities between the thermodynamic properties of the two species. Membrane separation shed new light for this application . In particular, Carbon Molecular Sieve Membranes (CMSM) have shown higher values in both the selectivity and fluxes.  

This research prepared CMSMs from a commercially available polymer Kapton®  Polyimide for the separation of N2/CH4 and CO2/CH4 gas pairs. The membrane were pyrolyzed at 3 different temperatures (600, 700, and 800°C) and tested for pure gas of N2, CO2, CH4, and Helium. 

The permeation data showed that the membrane with good separation performance for CH4/N2 gas pair as well as for CO2/CH4 gas pair with interesting results in gas separation. By comparing the permeation fluxes at different temperatures and membrane of different thicknesses, the effect of surface diffusion/surface flux were found  to be significant for sorptive species like CO2 and CH4, but less prominent on N2 and helium.