Research subject: Multi-component catalysts based on metal-organic frameworks (ZIF-8), combined with various additives such as cerium oxide (CeO2) and zirconium oxide (ZrO2), have been developed separately to investigate the role that metal oxides, in combination with metal-organic frameworks, play in the conversion of CO2 to Methanol. The study seeks to explore how these metal oxides interact with ZIF-8 and contribute to improving the catalytic performance for the efficient conversion of CO2 into Methanol, which is an important process for reducing CO2 emissions and producing renewable fuels.
Research approach: The structural, physical, and chemical properties of the synthesized catalysts were meticulously analyzed using a variety of advanced techniques. These included XRD, FT-IR, BET, SEM, TGA, TPR, and H2/CO2 TPD. Unlike earlier studies focusing on a single oxide, this work highlights the comparative effect of two key oxides within the same catalytic framework using advanced characterization techniques. Cerium oxide (CeO2) plays a pivotal role in the catalytic system by creating strong basic sites, which are essential for activating CO2. It also facilitates the formation of different oxidation states (Ce3+ and Ce4+), which enhance the reducibility of the catalyst and increase its specific surface area. Meanwhile, zirconium oxide (ZrO2) significantly improves the dispersion of active sites within the catalyst structure, which leads to an increase in the number of active sites available for the CO2 hydrogenation process. Moreover, a controlled thermal treatment was applied to refine the formation and distribution of these active sites, resulting in an overall enhancement in catalytic performance.
Main results: The presence of cerium oxide improves the conversion of CO2 to Methanol by introducing more abundant and active basic sites, which facilitate the reaction. On the other hand, zirconium oxide improves the dispersion of active sites across the catalyst surface, leading to a significant increase in Methanol selectivity. These two metal oxides, when used in combination, play complementary roles in improving both the efficiency and selectivity of ZIF-8-based catalysts in the hydrogenation of CO2 to Methanol. The synergistic effect of these oxides makes the catalyst more effective, allowing for a more efficient CO2 conversion process.