CO2 hydrogenation to methanol with an innovative Cu/Zn/Al/Zr catalyst: Experimental tests and process modeling

In this study, an innovative Cu/Zn/Al/Zr catalyst for the conversion of CO2 and H2 into methanol is tested at laboratory scale (0.5 g of catalyst into a cylindrical fixed bed reactor, with 9.1 mm internal diameter). Fourteen experimental tests are performed under isothermal conditions (T = 250 °C), covering a range of pressure (3.0-7.0 MPa), Gas Hourly Space Velocity (4000-13,000 h-1) and H2/CO2 molar ratio (between 3 and 6) relevant to industrial applications, with or without CO in the feed mixture, with flow-rates ranging between 200 and 650 NmL min-1. Based on the established Graaf's kinetic model, new kinetic parameters are calibrated and a plug-flow model of the isothermal reactor is implemented and simulated in Aspen Plus. A reasonable agreement between experimental data and calibrated model is achieved, with deviations lower than 10% of the measured flow rates for each species in the product stream. CO2 conversion up to 26% and methanol yields up to 13% are obtained during the test campaign (test run #12). The model represents a valid tool for future research or engineering studies targeting the design and performance assessment of demo/full-scale CO2-to-methanol synthesis processes based on the Cu/Zn/Al/Zr catalyst introduced in this paper.