Tuning RHO Zeolite Crystallization Time and Precursors for Stable and Improved Methanol Conversion to Dimethyl Ether Compared to Conventional Catalysts

Energy supply is a significant concern that can be addressed by developing sustainable energy sources. Dimethyl ether (DME) shows remarkable promise in this regard, as it finds applications in diesel fuel engines and LPG systems and serves as an excellent carrier for H-2. In this study, various RHO samples were synthesized by modifying preparation parameters and evaluated for their performance in this reaction. Through characterization analyses such as XRD, BET, NH3-TPD, SEM, EDS, and reactor experiments, it was determined that the optimized sample with the highest crystallization degree (10 days of hydrothermal crystallization) and synthesized with a template:Al2O3 ratio of 0.5:1 possessed an optimum weak/strong acid sites ratio of 1.49 which effectively addressed the limitations of previous catalysts, such as high-temperature requirements and rapid deactivation. The RHO sample achieved the highest conversion rates at temperatures as low as 190 degrees C, maintaining its efficacy for several days. It was observed that the RHO sample performed superior to common ZSM-5 zeolite for this reaction owing to its higher acidity (2560 mu mol g(-1) against 1940 mu mol g(-1)) and surface area (671 m(2) g(-1) vs 230 m(2) g(-1)). These findings highlight the potential of DME as a sustainable energy source and emphasize the importance of optimizing catalyst preparation to improve the DME production efficiency and cost-effectiveness.