(300b) Membrane Reactors for Equilibrium-Limited Alcohol and Light Hydrocarbon Synthesis

Authors: 
Li, Z., University of Southern California
Entesari, N., University of Southern California
Tsotsis, T., University of Southern California
Reaction and separation are two of the most crucial steps in chemical plants. Performance of each of these two steps can strongly affect the profitability of a given process by affecting its raw materials and energy demand. To improve the overall performance of the process, reaction and separation can be combined into a multifunctional Membrane Reactor (MR). Such reactors typically consist of a catalyst bed in contact with a high-temperature membrane and increase process synergy, reduce by-product formation as well as amount of reactants consumed. Additionally, a considerable reduction in the overall energy costs is to be expected. While there are several reports on the applications of MR for both gas and liquid phase reactions, further studies are still required to move towards commercialization of these MRs.

In this talk, we will present two different examples of high-temperature MRs. The first is an extractive MR that is used for methanol (MeOH) synthesis, and the other a contactor MR that is used for carbon (CO2) capture and utilization (CCU). Synthesis of MeOH from syngas is a severely equilibrium-limited reaction, meaning that a large fraction of the unreacted syngas feed, must be recycled to make this equilibrium-limited process economically feasible. The ability of MR to increase the per-pass yield makes them an optimal choice for process intensification, particulalry for coal-derived and biomass-derived syngas from air-blown gasifiers that contains considerable amounts of inert N2.

Power plants are responsible for a large fraction of the man-made carbon-dioxide emissions, and are major contributors to the green house effect. The key challenge here is the dilute CO2 concentration in the flue-gas, which make the conventional approaches such as direct sequentration technically as well as economically inefficient. Coupling of reaction and separation in a contactor MR, provides the driving force for the separation which moderates the challenge, and can also produce valuable products (e.g., synthetic natural gas, alcohols, etc.) which can be used as fuels to reduce the overall energy demand of the plant, and to improve its efficiency.

During our talk, we will present two MR configurations, and will discuss the influence of reaction conditions and separation efficiency on the final yield of the reaction. The different types of high-temperature membranes that have been investigated will be described, and the influence of membrane characteristcs on overall system performance will be described. Efforts to optimize MR performance both experimentally and numerically will be furher outlined.