Effect of the Y2O3 Promoter on the Structure of the Ni/Al2O3 Catalyst for Ethanol Autothermal Reforming.

The Ni/Al2O3 catalyst is a viable alternative in catalytic reforming due to its excellent ethanol conversion and lower cost; however, it still suffers from deactivation by coke deposition. Doping the Ni/Al2O3 catalyst with yttrium oxide (Y2O3) neutralizes the acidic sites of the support, mitigating the reactions that lead to deactivation. In this work, Ni/Al2O3 catalysts with 1% and 2% Y2O3 were prepared by the wet impregnation method, dried at 90 °C for 24 h, and calcined at 975 °C for 5 h. The catalysts were characterized by N2 physisorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), temperature-programmed reduction (TPR), and H2 pulse chemisorption. The addition of the promoter reduced the temperature required for the reduction of nickel oxide (NiO) to Ni0 due to the lower formation of NiAl2O4 spinel. The Ni(10%)/Y2O3 (1%)Al2O3 (S3) catalyst achieved 100% ethanol conversion and superior selectivities for H2 and CO2 during 480 min at 600 °C, with an H2O/C2H5OH/O2 molar ratio of 3:1:0.5 and a space velocity of 1300 h-1. Thermogravimetric analysis (TGA) indicated low coke formation (<1 mgcoke/mgcatalyst) for all catalysts and showed that the catalyst doped with 1% Y2O3 did not exhibit mass gain associated with the oxidation of Ni0 to NiO. Therefore, Y2O3 proved to be an effective promoter for increasing the activity and stability of Ni/Al2O3 catalysts in the autothermal reforming of ethanol.