Liquid-Phase Syngas-To-Methanol at Low Temperature: Mixed Alcohol Solvent-Controlled Pathways for Circular Carbon Manufacturing.

Methanol is a primary platform chemical for circular manufacturing. Low-temperature liquid-phase methanol synthesis provides an energy-efficient route for valorizing syngas under mild conditions. In this study, we explore the effect of mixed alcohol solvents-specifically 2-butanol and isopropanol-on methanol production over a commercial CuO/ZnO/Al2O3 catalyst at 170°C and 5 MPa. These two alcohols were selected based on prior reports of high reactivity, with 2-butanol showing superior performance but at a higher cost. A series of reactions with varying 2-butanol content (0%-100%) revealed a nearly linear relationship between solvent composition and methanol yield, suggesting minimal interaction between the two alcohols. Product analysis identified isopropyl formate as the only observable ester intermediate when isopropanol was present, while no 2-butyl formate was detected. These findings clarify how solvent choice influences intermediate stability and methanol productivity, providing guidance for process optimization. Beyond reaction chemistry, this approach integrates with Regenerative Robust Gasification (RRG), which converts heterogeneous organic waste streams into syngas upstream and channels methanol downstream into products, polymers, packaging, and other circular products, advancing circular economy strategies under industrially relevant conditions.