Zr-modified Cu-ZnO-Al2O3 catalyst integrated with bio- templated HZSM-5 for Methanol/DME production from CO2 hydrogenation

Background The conversion of CO 2 into value-added fuels and chemicals remains one of the major challenges in catalysis and sustainable energy research. Developing efficient catalysts for CO₂ hydrogenation to methanol and dimethyl ether (DME) is essential for reducing greenhouse gas emissions and promoting carbon recycling. Methods In this work, a Zr-modified CuO–ZnO–Al₂O₃ (CZZA) catalyst was synthesized via a co-precipitation method for CO 2 hydrogenation. The catalyst systems “CZZA/HZSM-5-L” and “CZZA/com-HZSM-5” represent Zr-modified CZZA physically integrated with loofah-templated and commercial HZSM-5 (Si/Al = 25), respectively. A bio-HZSM-5 catalyst was also prepared using loofah sponge and rice husks as dual biotemplates to promote methanol dehydration into DME. The novelty lies in (i) the dual-biomass templating strategy (silica-rich rice husk vs. low-silica loofah) to achieve macro– meso –micro hierarchies while retaining MFI crystallinity, and (ii) Zr-promotion of the Cu–ZnO–Al₂O₃ matrix to enhance Cu⁺/Cu²⁺ and Cu–Zn interfacial sites, enabling efficient one-pass CO₂ → MeOH → DME conversion at 280 °C and 30 bar. Significant findings Zr incorporation significantly improved the structural and electronic properties of the CZZA catalyst, leading to enhanced surface area, active site dispersion, and CuO–ZnO interfacial synergy. Among all tested catalysts, the CZZA/HZSM-5-L bifunctional catalyst achieved the highest DME yield (13.2 %), DME selectivity (58.6 %), and CO₂ conversion (22.5 %) at 280 °C and 30 bar. An economic evaluation of 5- and 10-ton-per-day (TPD) DME production using refinery waste CO₂ showed payback periods of 2.98 and 2.44 years, respectively. Sensitivity analysis (±20 % variation in H 2 and DME prices) confirmed the payback remained below 4 years, demonstrating the technical and economic viability of the developed Power-to-DME process.