Mathematical Modelling of the Kinetics of Biomethanol Production on a Fibrous Cu/Zn/Al/Zr Catalyst from Biomass-Derived Syngas

The accelerated growth of the global economy has contributed to the shift towards sustainable energy sources, amplifying the need for biomethanol production from biomass-derived syngas. This study evaluated an extensive kinetic model incorporating equilibrium restrictions for biomentanol synthesis utilizing a fibrous Cu/Zn/Al/Zr catalyst. A modified Langmuir–Hinshelwood–Hougen–Watson (LHHW) model was employed to better capture the equilibrium effects of CO hydrogenation, CO₂ hydrogenation, and reverse water gas shift (RWGS) for precise predictions. Parameters evaluated included temperature (200-300°C), pressure (50-100 bar), H₂/CO ratio (1.5–2.5), and H₂/CO₂ (2.5–3.5) molar feed and space velocity (100-1000 h⁻¹). LHHW rate constants were calculated from pilot scale experimental data, and the model bioethanol yield was compared against ground truth values, yielding a deviation of 7.23%. The LHHW was solved with the ODE15s solver in MATLAB to address the stiff equations generated by the LHHW model. Sensitivity analysis evaluated by the finite difference technique assessesed the uncertainty of biomethanol yield, highlighting that pressure had the most influence. From this, an 11.70% yield increase was seen when pressure was raised from 65 to 75 bar. ChemCAD8 was employed for process flowsheeting, enabling quantification of the biomethanol yield, and analyzed with the coefficient of determination (R²), root mean squared error (RMSE), mean squared error (MSE), and mean absolute error (MAE). The model attained an R² of 0.9756, an MSE of 0.2453, an RMSE of 0.4953, and an MAE of 0.035. A plug‐flow reactor simulation reached 0.402 kg methanol per kg biomass with 87.3 % CO₂ conversion, compared to experimental values of 0.379 kg/kg and 81.4 %. The simulation carried a ±4.23 % uncertainty at 95 % confidence. These results were generated at optimal points spanning 246 °C, 78 bar, 379 h^-1, H₂/CO=2.3, and H₂/CO₂=3. The refined kinetic model accurately predicted biomethanol performance; however, for effective scale-up application, heat management of the catalyst should be practiced.