Sulphur poisoning, water vapour and nitrogen dilution effects on copper-based catalyst dynamics, stability and deactivation during CO2 reduction reactions to methanol

Abstract

To reduce CO₂ emissions, a flexible process operation for chemical methanol synthesis may be required as the supply of renewable energy-based feedstocks fluctuates. Analysis for the determination of the changing conditions of the long-term activity of catalysts is therefore important for efficient industrial production. A commercial Cu/ZnO/Al₂O₃ catalyst and five other materials (CuBaTiO_X, CuCaTiO_X, CuCeAlO_X, CuSrAlO_X and CuSrTiO_X), prepared using solution combustion methods, were tested at two different pressures (p), followed by ageing at high temperature (T) jumps to show the effects of sensitivity. Surfaces were characterized by N₂ physisorption, scanning electron microscopy, coupled with energy dispersive spectroscopy (SEM-EDS), and crystallographic X-ray diffraction (XRD) with additional structural Rietveld refinement. Stability reduction mechanisms were assessed, a model was developed with the applied relative partial p of reaction product species as input, and, for CuCeAlO_X, it was demonstrated that the kinetics of deactivation is related to a unified H₂O gage p distribution, while excluding the correlations of other four prevalent gases (hydrogen, carbon dioxide, carbon monoxide and methanol). An activity decrease can be predicted. Interestingly, synthesized SrCO₃-containing mixtures exhibited a lesser loss of initial methanol synthesis activity at 50 bar than at 20 bar during time-on-stream increased T application. In addition, the activity relationship of the catalysts with N₂ and H₂S poisoning was described. A linear performance differentiation as a function of the amount of H₂S impurity was observed, presented and mechanistically modelled. Carbon capture and utilisation technologies, power-to-liquid and e-fuels, will often require (realistic) non-steady state dynamics, which we herein simulate catalytically.