(560bm) Promoting CO2 Hydrogenation Activity and Methanol Selectivity of Cu/CeO2 Catalyst By W-Doping

The direct hydrogenation to methanol provides a facile CO₂
reactivation pathway for the carbon capture and utilisation scheme. Amongst the
various CO₂ hydrogenation catalysis systems, Cu/CeO₂ has
received considerable research attention owing to the ability of CeO₂
to efficiently activate CO₂ at its surface oxygen vacancies through
the highly active Ce⁴⁺/Ce³⁺ redox cycle. However, the
application of Cu/CeO₂ for direct methanol synthesis is limited by its
mediocre selectivity towards methanol. In the present study, we present a W-doping
approach to promote the performance of the Cu/CeO₂-based catalysts.
The synthesised W-Cu/CeO₂ achieves an eight-fold increase in
turn-over-frequency (TOF) for CO₂ conversion over unmodified Cu/CeO₂,
as well as a methanol selectivity of >86% at 230 °C and 3.5
MPa, with stable performance over 72 h time-on-stream.
XPS results suggest that the improved TOF is attributed to the enhanced
activity of the Ce⁴⁺/Ce³⁺ redox pair. Operando DRIFT data
reveal that the methanol synthesis proceeds via the CO pathway on both Cu/CeO₂
and W-Cu/CeO₂. The observed (i) strong CO₂
and CO adsorption and (ii) weak methoxy adsorption are responsible for the superior
performance of the W-Cu/CeO₂ catalyst.