Effect of the Y ₂ O ₃ Promoter on the Structure of the Ni/Al ₂ O ₃ Catalyst for Ethanol Autothermal Reforming

High Resolution Image Download MS PowerPoint Slide The Ni/Al 2 O 3 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/Al 2 O 3 catalyst with yttrium oxide (Y 2 O 3 ) neutralizes the acidic sites of the support, mitigating the reactions that lead to deactivation. In this work, Ni/Al 2 O 3 catalysts with 1% and 2% Y 2 O 3 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 N 2 physisorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), temperature-programmed reduction (TPR), and H 2 pulse chemisorption. The addition of the promoter reduced the temperature required for the reduction of nickel oxide (NiO) to Ni 0 due to the lower formation of NiAl 2 O 4 spinel. The Ni(10%)/Y 2 O 3 (1%)─Al 2 O 3 (S3) catalyst achieved 100% ethanol conversion and superior selectivities for H 2 and CO 2 during 480 min at 600 °C, with an H 2 O/C 2 H 5 OH/O 2 molar ratio of 3:1:0.5 and a space velocity of 1300 h –1 . Thermogravimetric analysis (TGA) indicated low coke formation (<1 mg coke /mg catalyst ) for all catalysts and showed that the catalyst doped with 1% Y 2 O 3 did not exhibit mass gain associated with the oxidation of Ni 0 to NiO. Therefore, Y 2 O 3 proved to be an effective promoter for increasing the activity and stability of Ni/Al 2 O 3 catalysts in the autothermal reforming of ethanol.