(84r) Effect of Synthesis Method on Performance of Hybrid Catalyst for Direct DME Synthesis: Flame Synthesis and Co-Precipitation.

The direct conversion of CO₂ to dimethyl ether (DME) is regarded as an innovative approach for upcycling CO₂. The direct DME synthesis process is catalyzed over a hybrid catalyst. Cu/ZnO/MgO and Cu/ZnO/ZrO₂ synthesized by co-precipitation and admixed with γ-Al₂O₃ and H-ZSM-5 respectively have been identified as active and selective hybrid catalysts for direct DME synthesis [1,2]. The co-precipitation process involves several steps and requires long times for catalyst synthesis. To overcome these limitations of the co-precipitation process, flame synthesis, which is a continuous single step route, is used to obtain the same catalysts. Flame synthesis provides strict control of size, surface area, morphology, and crystal phase of nanoparticles [3]. Also, flame synthesis can result in the production of metastable phases which are not accessible to conventional wet synthesis methods.

In this work, Cu/ZnO/MgO and Cu/ZnO/ZrO₂ catalyst is synthesized via flame synthesis and admixed with γ-Al₂O₃, to design the hybrid catalyst. An alternate hybrid catalyst with Cu/ZnO/MgO and Cu/ZnO/ZrO₂ synthesized via co-precipitation and admixed with γ-Al₂O₃ is also designed. The hybrid catalysts activity, selectivity, and stability for direct DME synthesis from a CO/CO₂/H₂ mixture is evaluated and compared to observe the effect of catalyst synthesis route on the performance of the hybrid catalyst. Our finding show that the hybrid catalyst manufactured via flame synthesis provides a higher activity and higher selectivity for DME over that synthesized via co-precipitation. The characterization results reveal the structural characteristics which provides insight to describe the superior performance of the flame synthesized catalyst. Altogether, flame synthesis is used to elucidate the governing aspects for high performance catalysts for direct DME synthesis.

[1] Asthana, et al, Energy & Fuels 36;5 (2022) 2673-2687.

[2] Singh, et al, Fuel 318 (2022) 123641.

[3] Okonkwo et al, Journal of the American Ceramic Society 105;2 (2022) 1481-1490.