Transport-Optimized Nanoporous Materials for Mass Separation and Conversion as Designed by Microscopic Diffusion Measurement

Abstract

Nanoporous materials find widespread application in material upgrading by separation (“molecular sieving”) and catalytic conversion. Mass transfer in these materials is a key phenomenon deciding about their technological performance. This chapter deals with the application of measurement techniques which are able to follow the diffusive fluxes of the guest molecules in such materials over “microscopic” distances, including the pulsed field gradient (PFG) technique of Nuclear Magnetic Resonance (NMR) and the techniques of microimaging by interference microscopy (IFM) and by IR microscopy (IRM). Microscopic measurement is a prerequisite for attaining unbiased information about the elementary steps of mass transfer and about their role within the overall process of technological exploitation. We dedicate this treatise to the memory of our dear and highly esteemed colleague Nicolaas Augustinus Stolwijk, notably in recognition of his manifold activities in the field of diffusion, distinguished by their impressively high standard in connecting the message of various techniques of measurement and in combining them to comprehensive views on quite intricate subjects.