Supercritical fluid-assisted modification combined with the resynthesis of SmCoO 3 as an effective tool to enhance the long-term performance of SmCoO 3 -derived catalysts for the dry reforming of methane to syngas.

The dry reforming of methane to syngas (DRM) is of increasing significance concerning, first, the production of raw materials for commercial organic/petrochemical syntheses and for hydrogen energetic, and, second, the utilization of two most harmful greenhouse gases. Herein, new SmCoO ₃ -based DRM catalysts derived from heterometallic precursors and operated without preliminary reduction are reported. For the first time, the effect of supercritical fluids-assisted modification of the SmCoO ₃ -derived catalysts combined with the re-oxidation of spent catalysts to SmCoO ₃ onto its long-term performance was studied. In particular, the modification of heterometallic precursors by supercritical antisolvent precipitation (SAS) considerably decreases coke formation upon the exploitation of the derived SmCoO ₃ sample. Moreover, the re-oxidation of the corresponding spent catalysts followed by pre-heating under N ₂ affords catalysts that stably provide syngas yields of 88-95% for at least 41 h at 900 °C. The achieved yields are among the highest ones currently reported for DRM catalysts derived from both LnMO ₃ perovskites and related oxides. The origins of such good performance are discussed. Given the simplicity and availability of all the applied methods and chemicals, this result opens prospects for exploiting SAS in the design of efficient DRM catalysts.