Machine learning-driven optimization for sustainable CO2-to-methanol conversion through catalytic hydrogenation
Seyyed Alireza Ghafarian Nia, Hossein Shahbeik, Alireza Shafizadeh, Shahin Rafiee, Homa Hosseinzadeh‐Bandbafha, Mohammadali Kiehbadroudinezhad, Sheikh Ahmad Faiz Sheikh Ahmad Tajuddin, Meisam Tabatabaei, Mortaza Aghbashlo
Abstract
Growing concerns about greenhouse gas emissions have accelerated research into converting CO 2 into valuable products like methanol. Catalytic hydrogenation, utilizing a catalyst in a thermochemical process, offers a promising solution for reducing atmospheric CO 2 and combating climate change. However, optimizing operating conditions and selecting suitable catalysts for CO 2 to methanol conversion remains challenging due to the complex interplay between catalyst properties and reaction performance. This research leveraged machine learning (ML) to model CO 2 to methanol conversion using a comprehensive experimental database. ML models were developed to predict CO 2 conversion efficiency, methanol selectivity, and CO selectivity, facilitating process optimization, techno-economic analysis, and life cycle assessment (LCA). The gradient boosting regression model emerged as the most accurate, with coefficients of determination (R 2 > 0.86) and low error metrics (RMSE < 9.99, MAE < 5.99). De novo predictions demonstrated an acceptable linear relationship with the completely unseen dataset. Feature importance analysis identified temperature and gas hourly space velocity (GHSV) as the most significant descriptors. The optimal conditions for maximum CO 2 conversion efficiency and methanol selectivity were identified as temperatures between 330 and 370 °C, a pressure of 50 bar, and a GHSV of 6,500–14,000 mL/g.h. The techno-economic analysis highlighted H 2 purchase price, methanol selling price, and CO 2 feedstock costs as critical economic factors, with a payback period of 4.6 years. The LCA demonstrated a 270 % reduction in carbon emissions through catalytic hydrogenation of CO 2 to methanol. This study underscored the importance of using sustainable H 2 and electricity sources to enhance the economic and environmental benefits of the process.