Experimental study and comprehensive kinetic modeling of the direct dimethyl ether synthesis on Cu/ZnO/ZrO2 and H-FER-20

In the direct dimethyl ether (DME) synthesis, the combination of Cu/ZnO/ZrO2 (CZZ) and H-FER-20 (FER) has shown high selectivity and productivity for a broad range of CO2/COX ratio. Aiming to understand the behavior of the studied catalyst system under distinct operating conditions, we developed a new 9-parameter kinetic model. The parameters were estimated based on 815 steady-state experiments carried out at several values of pressure (30-54 bar), temperature (190-250 celcius), space-velocity (0.79-4.34 s 1) and inlet gas composition. This broad database was used in the development and validation of a new 9-parameter kinetic model for the direct DME synthesis. The model adequately simulates experiments in several process conditions, with 95% of the simulated points presenting a deviation lower than 20% with respect to the experimental results for outlet DME molar percentage. In addition, it correctly predicts the trends with respect to variations in H2 inlet fraction, which is of high relevance for processes using fluctuating renewable power sources for H2 production. In comparison to state-of-the-art models with more parameters, the new model is significantly more accurate. It benefits from the broad range of validity and elevated number of experimental points, which makes it a reliable model that can be applied for process optimization and scale-up.