Abstract
Novel reactor configurations for the oxidative coupling of methane (OCM), and in particular membrane reactors, contribute toward reaching the yield required to make the process competitive at the industrial scale. Therefore, in this work, the conventional OCM packed bed reactor using a Mn-Na2WO4/SiO2 catalyst was experimentally compared with a membrane reactor, in which a symmetric MgO porous membrane was integrated. The beneficial effects of distributive feeding of oxygen along the membrane, which is the main advantage of the porous membrane reactor, were demonstrated, although no significant differences in terms of performance were observed because of the adverse effects of back-permeation prevailing in the experiments. A sensitivity analysis carried out on the effective diffusion coefficient also indicated the necessity of properly tuning the membrane properties to achieve the expected promising results, highlighting how this tuning could be addressed.
Highlights
The continuous trend of oil price increases, together with the growing demand for light hydrocarbon worldwide, are the main causes why interest for alternative technologies to produce light hydrocarbons is exponentially rising.The production of ethylene can be used as a representative example of this trend
If we consider that Cruellas et al [44] recently showed that the integration of porous membranes makes ethylene cheaper than when dense membranes are employed in an industrial-scale oxidativecoupling couplingofof methane (OCM) plant, the selection of porous membranes was warranted to carry out the experimental part of this work
OCM membrane porous membranes werewere usedused to build up theup reactor reactor because of their simplicity and comparable performance
Summary
The continuous trend of oil price increases, together with the growing demand for light hydrocarbon worldwide, are the main causes why interest for alternative technologies to produce light hydrocarbons is exponentially rising. The well-known OCM kinetics developed by Stansch et al [3] showed this behaviour, since the reaction order with respect to the oxygen of the primary desired reaction is lower than that of the undesired reaction Based on this fact, distributed oxygen feeding along the reactor contributes to keep the local oxygen partial pressure low (providing high C2 selectivities), while maintaining overall decent CH4 conversion, resulting in. If we consider that Cruellas et al [44] recently showed that the integration of porous membranes makes ethylene cheaper than when dense membranes are employed in an industrial-scale OCM plant, the selection of porous membranes was warranted to carry out the experimental part of this work. The main objective of this work is the experimental comparison between packed bed and packed bed membrane reactor performances, highlighting the main parameters that should be optimized to maximize the theoretical OCM performance improvement expected with the membrane reactor
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