NUCLEAR-MAGNETIC-RESONANCE STUDIES OF POROUS-MEDIA

Nuclear Magnetic Resonance (NMR) is becoming an increasingly popular m easurement technique in chemical engineering research because of its a bility to probe both microscopic and macroscopic phenomena. In this pa per an overview of ongoing research projects in the area of characteri sation of porous solids, and the adsorption and transport phenomena as sociated with molecular species sorbed within porous materials is give n. NMR allows us to probe many processes non-invasively for the first time; these data give us new information which can then be used to des ign or optimise processes. Research in this area has followed two main themes. Firstly, a combination of NMR Imaging, PGSE and relaxometry m ethods in combination with numerical simulation techniques are used to study structure-transport relationships in amorphous, porous catalyst pellets. These studies emphasize the importance of characterising str uctural heterogeneities within a porous medium if the transport charac teristics of the macroscopic sample are to be adequately modelled. Sec ondly, deuterium spectroscopy studies of single and binary component a dsorption in zeolites are presented. These experiments allow us to exp lore effects such as adsorption heterogeneity and molecular traffic co ntrol and to yield a physical understanding of otherwise anomalous ads orption behaviour in zeolites. The insight into adsorption phenomena g ained by this technique suggests the possibility of optimising adsorpt ion-separation and catalytic processes by co-adsorbing specially, sele cted species within the pore structure of the zeolite.