| In addition to improvements gained from the combination of reaction and separation, further enhancement in membrane reactor performance can be obtained by proper catalyst formulation and by spatial distribution of the catalyst within the pellets (Packed Bed Membrane Reactor (PBMR)) or the membrane (Catalytic Membrane Reactor (CMR)). The objective of this work was to evaluate the reactor performance for the PBMR and CMR using different catalyst distributions.;Chapter 1. Background information on the synthesis, permeation mechanisms and applications for inorganic membrane reactors are presented. In addition, a brief review of the area of nonuniform catalyst distribution is also given.;Chapter 2. For the CMR, it is shown theoretically that in many cases of practical interest, the optimum distribution of catalyst within the membrane is a step-function.;Chapter 3. For a first order isothermal reaction, the performance characteristics of the PBMR, CMR and fixed-bed reactor (FBR) are compared for uniform and Dirac-delta catalyst distributions. The Dirac-delta distribution is shown to yield the highest performance.;Chapter 4. Experimental procedures for catalyst and membrane synthesis, characterization and reaction studies involving the dehydrogenation of ethane are described.;Chapter 5. For the PBMR, the inert membrane with desired permeation properties (i.e. minimize reactant loss) and the optimum Pt-Sn/;Chapter 6. For the CMR, the catalysts derived from alumina sol are synthesized, characterized and the best catalyst composition for the dehydrogenation of ethane is determined. Catalytic membranes with controlled activity distributions are prepared using the multiple slip-casting technique of inert and catalytic sols.;Chapter 7. For the dehydrogenation of ethane, the effects of nonuniform catalyst distribution, membrane thickness and other operating conditions are evaluated experimentally (PBMR) and theoretically (PBMR and CMR). A general model is developed to include the effect of nonuniform catalyst distributions. Using the results of chapter 5, the PBMR experiments are found to be in good agreement with theoretical predictions, obtained without the use of any adjustable parameters. The CMR model is also demonstrated using measurements of chapter 6. Supra-equilibrium conversions, about 80% above equilibrium values, are obtained with the narrow surface-step catalyst pellets (PBMR) and membranes (CMR). |
