(381g) Experimentally Simulating Dehydrogenation Catalysis in H2-Removal Membrane Reactors, without Using Membrane Reactors

Olefins are important precursors to materials such as plastics, rubbers, lubricants, surfactants and detergents, and as such, their industrial production is important. One method of olefin production is via alkane dehydrogenation, which is a class of reaction that converts alkanes to olefins and H₂, and is practiced industrially on large scale. For example, ethylene production is principally achieved today by ethane steam cracking, a non-catalytic thermal process, while other olefins like propylene are produced via catalytic dehydrogenation from their respective alkanes, and are typically run at reaction temperatures lower than steam cracking. The thermodynamic equilibrium conversion (X_eq) for alkane dehydrogenation limits achievable conversions in any closed system, and is one major reason why higher temperatures and lower pressures are favored process conditions. However, if the system is perturbed, for example by H₂ removal, these limits can change as a manifestation of Le Chatelier’s principle. In this regard, routes to perturb the dehydrogenation system have been pursued, and one route is the use of membrane reactors which can selectively transport H₂ through the membrane walls, thereby increasing X_eq. In this work, a method was developed to experimentally simulate what a catalyst will experience in a membrane reactor under a large range of conversions and H₂ removal levels, without having to use a membrane reactor, with a focus on the effects on catalysis. Notably, while membrane reactors, in principle, can increase X_eq, these new thermodynamic conversions may not be attainable due to exacerbation of coking reactions, which produce H₂ thereby limiting conversions and and cause significant catalyst deactivation.