Understanding membrane-intensified catalytic CO2 reduction reactions to methanol by structure-based multisite micro-kinetic model

Abstract

Membrane reactor processes can be used to overcome the constraints of the chemical rate equilibrium of methanol (MeOH) synthesis products. In this thermodynamics-limited work, three different selective sulfonated poly(ether ketones) (SPEEK) membranes were applied in an engineered unit operation with a commercial Cu/ZnO/Al2O3/MgO surface catalyst for several CO2/CO-involving chemistries. A detailed mathematical model with micro-kinetics was developed, optimised and utilised to assess the vessel with barrier by using CERRES (Chemical Reaction and Reactor Engineering Simulations). Scaled separation tests were described by the integrated reference values of permeance. The permeability for all compound molecules (H2, H2O, CO, CO2, MeOH) was determined by adjusting parameters to account for the experimental gas composition on the permeate, interface and retention segment side after reduction. The specific kinetic characteristics of the mechanism of elementary step reactions were analysed in fixed bed design. A comparison of the estimated data prediction for the packed system with related definite numbers showed excellent statistical agreement. Similarly, a very good reliability was obtained between the results for 3 SPEEK membrane cases. Thus, the defined particular evaluations of derived theoretical expressions were benchmarked accurately. Although (validated) performance, i.e. the yield of MeOH, was overestimated, discrepancy was not so large so as to simulate behaviour verily. The (3-aminopropyl)triethoxysilane (polyamide) over a SPEEK layer performed best for intensification. Herein, the pressurised (>50 bar) CO2 hydrogenation pathway was not only shifted by in situ removal as a proof of concept, but also modelled intrinsically, considering transport phenomena resistances, adsorption and desorption as well. The storage of hydrogen can benefit from MeOH production reengineering.