Steering the Aspects of MgO-Induced Structure Sensitivity in Cu-Based Catalysts for CO2‑Rich Syngas Conversion to Dimethyl Ether: Cu/Zn Ratio and Lattice Parameters

• Published in: Energy & fuels 2022-03, Vol.36 (5), p.2673-2687
• Main Authors: Asthana, Sonal, Samanta, Chanchal, Saha, Basudeb, Voolapalli, Ravi Kumar, Pant, Kamal Kishore
• Format: Article
• Language: English
• Subjects: Environmental and Carbon Dioxide Issues
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.1c03945

The present work reports the crucial effect of the Cu/Zn ratio and MgO content (10–30%) on lattice parameters as well as the metal surface area of the co-precipitated Cu–ZnO–MgO/γ-Al2O3 bifunctional catalyst for direct dimethyl ether (DME) synthesis from CO2-rich syngas (H2/CO = 2). X-ray diffraction analysis of the as-synthesized catalysts showed a prominent structural identity belonging to the malachite–rosasite [(Cu,Zn)2(CO3)­(OH)2] group of minerals. Progressive addition of MgO into the Cu-based catalysts (Cu/Zn ratio = 2–4) exhibited an overall decrease in the cell volume, providing it the required stability. The catalyst possessing the lowest unit cell volume (V m) exhibited the highest metal surface area, enhanced Cu dispersion, and improved DME synthesis with a negligible decrease in activity over 72 h on stream. The catalytic functionalities, such as total carbon (CO + CO2) conversion (45.6%), CO2 conversion (12.8%), and DME selectivity (90.9%), showed their maxima on the optimized bifunctional catalyst CZ[2]–M(20). Also, the hydrocarbon selectivity was found to be least for this catalyst.