The catalytic oxidative coupling of methane (OCM) process has received intense scientific and commercial interests during the past decades. It offers the potential to directly convert methane to higher hydrocarbons (e.g., ethylene) from natural gas, and thus to reduce cost, energy, and carbon emissions. However, conventional industrial reactors (e.g., packed bed reactor and fluidized bed reactor) for this process suffer from low ethylene yields, high operating temperatures, and fast catalyst degradation, which hinder the commercialization of this technology (Tiemersma et al., 2012). To drive the innovation in OCM processes, a model-based reactor design approach can be useful in generating the optimal reactor design accounting for novel reactor concepts and benchmark with conventional process solutions. The aim of this work is to design an optimal OCM process at commercial scale leveraging the concept of modular process intensification. We investigate an intensified fluidized bed membrane reactor (FBMR) catalyzed by La2O3/CaO, and compare its performance to a conventional fluidized bed reactor (FBR). The use of membrane for oxygen feed distribution has been reported to result in better ethylene yield and selectivity by selectively enhancing the desired reactions, but also adds to capital cost investment and scaling up challenges. To systematically identify the optimal design solution, high fidelity FBMR and FBR models are developed in gPROMS ModelBuilder, which comprise partial differential algebraic equations accounting for mass balances, hydrodynamics, catalyst solid distribution, etc. A micro-kinetic model (with more than 350 elementary reactions) (Dooley et al., 2011) and a 10-step reduced kinetic model (Cruellas et al., 2020) are compared to study the impact of kinetics on reactor modeling and design . The two reactor configurations are optimized to obtain maximum profit, with the corresponding design parameters on reactor sizing, temperature, catalyst particle velocity, and membrane tube design (for FBMR). Extensions of the reactor models with operational optimization following the PARametric Optimization and Control (PAROC) framework will also be discussed (Pistikopoulos et al., 2015).

Process modeling, design, and intensification of oxidative coupling of methane process: A comparative study on membrane reactor and fluidized bed reactor

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.