ZEOLITE SYNTHESIS IN UNSTIRRED BATCH REACTORS .1. NUCLEAR-MAGNETIC-RESONANCE IMAGING OF NONUNIFORM PRE-MIXING

The application of nuclear magnetic resonance (NMR) imaging to the stu dy of the design and performance of chemical reactors is introduced. N MR imaging is a non-invasive technique which can be utilized for the i nvestigation of physical processes such as the mixing of reagents with in a sealed reactor. A series of experiments is described on the mixin g of aluminate solutions with silicate solutions or silica slurries wi thin zeolite crystal growth reactors. Mixing was followed by the imagi ng of protons present in triethanolamine (a nucleation suppressant) or tetraethylammonium bromide (a structure-directing agent) in sodium al uminosilicate mixtures which were otherwise fully deuterated. Composit ions suitable for the crystallization of zeolites A, X and mordenite, in four reactor designs, were studied. The reactors were designed spec ifically for the growth of large zeolite crystals in microgravity aboa rd the space shuttle. NMR imaging was shown to be a reliable indicator of the mixing process, provided the organic was present in sufficient concentration and that its distribution was representative of the dis tribution of the other reagents. The possibility of utilizing NMR imag ing to study a wide range of reactors, where other (invasive) techniqu es are unsuitable, is realized.