Zeolites are one class of porous materials that are currently being explored for sepn. applications in the aim of reducing environmentally harmful carbon dioxide (CO2) from the combustion of fossil fuels. The several archetypical zeolites being employed or researched for this include zeolites X, Y, beta, CHA, MFI. While much work has been done on the uptake and sepn. abilities of these zeolites in their various cation-exchanged forms, there is little in the way of understanding about how the adsorbed gases interact with the host frameworks or exchanged cations. There are two fundamental questions: Does the adsorbed gas interact with the Si/AlO4 framework or the exchanged cations And do those cations (and which cations) reorient or shift with increased gas concns. potentially hindering the sepn. ability Powder neutron diffraction is a particularly useful tool for the investigation of in situ gas adsorption allowing for the accurate detn. of the location of the adsorbed gas relative to the zeolite host and was employed to det. the relationship between the zeolites and gases. The zeolites (X, Y, beta, CHA, MFI) and gases (CO2, N2, CH4, H2) studied were detd. through available literature from the type of CO2 sepn. application (pre- or post-combustion) that each material excelled in sepg.