New Bifunctional Catalysts for the Synthesis of Dimethyl Ether Via Carbon Dioxide Utilization

Abstract

The increasing demand for sustainable energy sources has intensified research into carbon dioxide (CO2) utilization for the synthesis of clean alternative fuels such as dimethyl ether. This study investigates the direct synthesis of dimethyl ether from CO2 using bifunctional copper-based hybrid catalysts (SCR-A, SCR-B, and SCR-C) synthesized via the sol-gel method. These catalysts integrate oxidative and acidic functionalities within a single system, enabling methanol synthesis and subsequent dehydration into dimethyl ether in a one-step process. Experimental evaluations were conducted under varying pressures ranging from atmospheric to 40 bar and temperatures between 200-350 degrees C, using both low-and high-pressure reactors to assess performance. The results indicate that under atmospheric conditions, methanol conversion reached 87%, with 82% dimethyl ether selectivity, demonstrating the bifunctional character of the catalysts. Among them, SCR-A exhibited the most favorable performance in terms of conversion and product distribution. Under high-pressure conditions (5 and 7 bar), CO2 conversion remained constant at 50%, while selectivity was influenced by temperature and reactor pressure. At 40 bar and 300 degrees C, dimethyl ether selectivity reached its peak at 60%, confirming this range as the optimal operational window for maximizing dimethyl ether yield. However, a notable decrease in selectivity was observed at 350 degrees C, likely due to catalyst deactivation or the promotion of undesired side reactions. These findings underline the thermodynamic and operational benefits of direct dimethyl ether synthesis over the conventional two-step route, as it simplifies process design, enhances CO2 utilization, and reduces energy and cost demands