An experimental and modeling study of the application of membrane contactor reactors to methanol synthesis using pure CO2 feeds

Abstract

We describe here a post-combustion CO2 capture and utilization (CCU) technology that converts the CO2 into methanol (MeOH), a valuable chemical, thus providing a way to monetize the carbon captured to offset process costs. Methanol synthesis (MeS) has been discussed recently for application to CCU, but thermodynamic limitations make it difficult to convert in a single pass a large CO2 fraction. Conventional catalysts show slow kinetics in converting CO2-rich syngas (or pure CO2) into MeOH. Our Group developed (Li and Tsotsis, 2019) a novel MeS process, employing a membrane contactor reactor (MCR) system that attains carbon conversions significantly higher than equilibrium. Our focus here is to process pure CO2 streams by combining the MCR with a separate reactor, which converts the CO2 into a syngas via the reverse water gas shift (RWGS) reaction. In this preliminary effort, the RWGS reactor (RWGSR) is assumed to reach equilibrium. Additional MeS kinetic rate data are generated validating experimentally the ability of the MeS-MCR to process as a feed the RWGSR exit stream. The performance of the combined (RWGSR/MeS-MCR) system is then simulated using a recently developed MeS-MCR model (Zejarbad et al., 2002). The findings are encouraging, and research is currently ongoing to experimentally validate the RWGSR/MeS-MCR system performance.