Anodic TiO2 nanotube array supported nickel - noble metal bimetallic catalysts for activation of CH4 and CO2 to syngas

Highly-ordered TiO2 nanotube array (TiNT) was prepared by an electrochemical anodization method and used as the support for Ni and Ni-M (M = Ru, Pt and Rh) bimetallic catalysts. Ni/TiNT and Ni-M/TiNT were then applied to the combination reactions of the partial oxidation of methane reaction (POM) with the carbon dioxide reforming with methane reaction (CRM) for the syngas production. The results show that Ni/TiNT suffers from the formation of NiO and NiTiO3, and the coke deposition. The superior catalytic performance and the enhanced resistance ability against carbon formation are obtained over a small amount of noble metal modified Ni bimetallic catalysts, which are ranked as Ni/TiNT < Ni-Ru/TiNT < Ni-Pt/TiNT < Ni-Rh/TiNT. The interaction of Ni-M, i.e., enhanced reducibility of NiO and the maintenance of metallic Ni species even in the presence of oxygen, over Ni bimetallic catalysts is regarded as an important reason. Much short distance between the exothermic and the endothermic zones over Ni-M/TiNT catalysts bed can be realized, and a flat temperature profile in the catalyst bed is expected, which in turn can relieve the hot-spot and NiTiO3 formation to some extent. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.