Thorium-promoted Cu/Zn/Al syngas catalyst for methanol synthesis with enhanced activity and stability

Abstract

The traditional Cu/Zn/Al catalyst for methanol synthesis from syngas usually exhibits structural instability and carbon deposition. In this work, a trace of thorium (1–20 wt‰) was incorporated to a typical Cu/Zn/Al catalyst for structural modification. It was found that the Th-promoted (5 wt‰) Cu-based catalyst showed an obviously enhanced activity and stability for methanol production from syngas. Under identical testing circumstances, the activity after heat resistance of CatTh5 was 27.3% higher than the original catalyst (Cat0) and 23.8% higher than the commercial catalyst (Cat327). The 250-hour stability test revealed that the ideal CatTh5 catalyst presented good activity and stability in comparison to the original Cat0 catalyst. To the best of our knowledge, this result can significantly outperform Cu/Zn/Al benchmarks and rival the state-of-the-art systems. XRD, N2 physisorption, N2O titration, solid-state NMR, H2-TPR, semi-in-situ XPS and semi-in-situ XAES were used to comprehensively investigate the improved catalytic properties. Th was shown as a textural promoter and it can boost both metal dispersion and reduction property of reactive Cu species. Therefore, the created larger Cu surface area, smaller CuO particles and higher proportion of Cu+/Cu0 sites were demonstrated to be responsible for the superior catalytic performances.