PNNL

Abstract

Capturing Xe from gas mixtures represents one of the most challenging molecular gas separations. In this communication, we demonstrate the ability of a zeolite membrane, denoted as SAPO-34 to effectively capture Xe from air. Specifically, SAPO-34 membranes showed air permeances as high as 2.3 x 10-7 mol/m2 s Pa (690 GPU) and separation selectivities as high as 30.1 for a molar feed of 9:1 air/Xe. Molecular sieving, competitive adsorption, and diffusivity differences played a critical role in the overall separation performance. Membranes were air selective due to favorable molecular sieving and differences in diffusivity between gases present in mixture and Xe, which were identified as the dominant separation mechanisms. The high air permeances, and high separation selectivities, make these membranes highly appealing as a potentially less energy intensive alternative to cryogenic distillation the benchmark technology used to separate these gases. We (Pacific Northwest National Laboratory) acknowledge US Department of Energy (DOE), Office of Nuclear Energy for adsorption. P.K.T. would like to acknowledge Dr Terry Todd at Idaho National Laboratory, Dr Robert Jubin at Oakridge National Laboratory, Dr John Vienna at Pacific Northwest National Laboratory (PNNL), Kimberly Gray, Dr. Patricia Paviet and Jim Breese (DOE-NE HQ) for programmatic support. PNNL is a multi-program national laboratory operated for the US DOE by Battelle under Contract DE-AC05-76RL01830.