| This Ph.D. thesis is devoted to develop zeolite containing catalytic composite membranes as interphase contactors in a multiphase reaction system. This concept, which may be applied to numerous multiphase reactions, has been tested for the oxyfunctionalization of n-hexane to a mixture of hexanol and hexanone, with hydrogen peroxide dilute solution. The catalytic reaction rate of n-hexane oxyfunctionalization observed with this device is comparable to the rates observed with the suspended catalyst in a conventional reactor. Previous kinetic investigations had confirmed that in oxyfunctionalization of n-hexane the reactions take place in the aqueous phase where the concentrations of the organic chemicals are very low due to their low solubilities. Usually a co-solvent must be used to increase the organics solubilities in the aqueous phase therefore increasing the reaction rates; In this new type of membrane reactor, a catalytic membrane is placed at the interphase between the two immiscible reacting phases and should allow adequate transport of both reactants towards the catalyst surface. In other words, in this membrane reactor, the membrane should play a role similar to the one of the solvent in the conventional reactor by affecting the reactants concentrations at the catalyst surface. Thus using this catalytic membrane interphase contactor the best advantage is to avoid the use of co-solvents.; The catalytic membranes consist of a polymeric matrix and the catalyst filler. The zeolitic catalyst, titanium silicalite (TS-1), shows several important potential advantages for the oxygenation of various organic compounds with dilute aqueous hydrogen peroxide. It is also thought to provide enough hydrophilicity to allow a proper transport Of H2O2 to the catalytic surface. The polydimethylsiloxane (PDMS) was chosen in this study because its CH3 groups make it compatible with n-hexane and because of its high resistance to oxidation due to the O-Si-O bridges involved. In several tests, some additional hydrophilicity was also given to the polymeric matrix by grafting polar functional groups to the PDMS matrix using chemical copolymer modifiers.; The experimental work includes titanium silicalite –1 catalyst preparation & characterization, membrane preparation & characterization, measurements of permeabilities of hydrocarbons and water in zeolite containing composite membranes, separation of hydrogen peroxide solution and mixyuure of n-hexane, hexanol and hexanone using a pervaporation process, and membrane catalytic reaction tests.; A computer model of the membrane reactor designated as the kinetic diffusion-reaction model was also developed and utilized in describing n-hexane oxyfunctionalization by H2O2 solution over catalytic membranes and predicting the effects of the composite membrane on n-hexane conversion and products (oxygenates) composition. It was also used to explain the effects of the membrane thickness, copolymer modifier, and catalyst particles loading and size on the reactants and products concentration profiles in the catalytic membrane. |
