High catalytic activity and stability of ZnLaAlO4 supported Ni, Pt and Ru nanocatalysts applied in the dry, steam and combined dry-steam reforming of methane

摘要

Three novel M/ZnLaAlO4 (M = 10%Ni, 3%Pt and 3%Ru) nanocatalysts as well as the common 10%Ni/gamma-Al2O3 sample were synthesized by the wet impregnation method and characterized by XRD, FE-SEM, TEM, temperature-programmed reduction (TPR), N-2 physisorption, FT-IR and TGA/DTA analyses. The catalytic activities of the four nanocatalysts were evaluated in dry (DRM), steam (SRM) and combined dry-steam (CRM) reforming of methane at atmospheric pressure, five various temperatures (600-800 degrees C) and three different GHSV values (3500, 7000, 10,500 h(-1)). Among the ZnLaAlO4 supported catalysts, the greatest and the least catalytic performances were measured for the 3%Ru/ZnLaAlO4 and the 3%Pt/ZnLaAlO4, respectively. Surprisingly, the TGA diagrams of the used nanocatalysts almost did not illustrated coke formation for the 3%Ru/ZnLaAlO4 and 3%Pt/ZnLaAlO4 (especially in the SRM process) that were supported by their FE-SEM images which did not display carbon deposition. All of the three ZnLaAlO4 supported catalysts revealed much higher catalytic activity and less coke content compared with the commercial 10% Ni/gamma-Al2O3 catalyst. Thus, we believe that (to the best of our knowledge) this is the first time that such extremely active noble nanocatalysts are obtained with exceptionally high resistance against carbon deposition on their surfaces. The very low onset reduction temperatures in the TPR profiles of the 3% Ru/ZnLaAlO4, 3%Pt/ZnLaAlO4 and 10%Ni/ZnLaAlO4 at 230, 264, 333 degrees C, respectively, reflected the convenient reducibility properties of these samples. Considering the catalytic efficiency and resistance against coke formation, the 3%Ru/ZnLaAlO4 was chosen as the best nanocatalyst for the DRM, SRM and CRM reactions among our four tested samples. (C) 2016 Elsevier B.V. All rights reserved.