Noble metal promoters for Ni catalysts: Use in the steam reforming of distillery wastewater

This study examines the performance of Ni-based catalysts (herein called NLH) promoted with noble metals (1 to 2 wt.% of Rh or Ru) supported on hydrotalcite-derived mixed oxides (HDMO) modified with La. These catalysts were tested, for the first time, for the steam reforming of distillery wastewater (DW), a problematic effluent of the wine distillery industry (generated during the production of ethanol or wine spirits), to produce renewable hydrogen. Characterization techniques, including hydrogen temperature-programmed reduction (TPR-H 2 ), temperature-programmed desorption of NH 3 and CO 2 (TPD-NH 3 , TPD-CO 2 ), transmission electron microscopy (TEM), Raman spectroscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), were employed to get insights about the prepared materials. Steam reforming tests were performed, the results of which showed H 2 yields in the following order: 2Rh/NLH ~ 1Rh/NLH > 2Ru/NLH > 1Ru/NLH > NLH. Stability tests demonstrated no H 2 yield loss for 2Rh/NLH or NLH after 24 hours on-stream. Coke formation rate was relatively low for all catalysts, and the conversion of total organic carbon and chemical oxygen demand in the condensate was above 99%. A test with real effluent, sourced from a Portuguese wine distillery, was also performed, providing a proof of concept as to the feasibility of the steam reforming of DW. The conversion of organic carbon and chemical oxygen demand in this test were both ca . 99%. • Screening of promoted catalysts for the steam reforming of distillery wastewater. • Catalysts promoted with noble metals improved H 2 yield for low space-velocity. • The 2 wt.% Rh catalyst showed the highest H 2 yield and stability during 24 h. • H 2 spillover effect was observed for the noble metal catalysts.