Coke-resistant Au-Ni/MgAl2O4 catalyst for direct methanation of syngas

Carbon deposition is one of the major issues for catalytic methanation, especially when using high CO content syngas (such as H-2/CO = 1) due to the inevitable Boudouard reaction. Here we report the significant enhancement on the coke-resistance of Ni/MgAl2O4 catalyst during methanation by modifying with Au. The coke-resistant property was increased with Au addition while the catalytic activity decreased with excess Au. High and stable syngas conversions can be obtained over Au-Ni/MgAl2O4 catalyst at 450-500 degrees C. With comprehensive characterizations by using BET, H-2 chemisorption, H-2-TPR, XPS, XRD, STEM, EDS, TEM, TG/DTA, Raman and TPH, we found that Au and Ni formed bimetallic nanoparticles of similar to 10 nm with electron donation from Ni to Au. The deposited carbon on the spent Au-Ni/MgAl2O4 is very similar to that on the spent Ni/MgAl2O4 in the nature and in the gasification behaviour but is significantly less. These results suggest that the enhanced coke-resistance of Au-Ni/MgAl2O4 is presumably due to the suppression on CO disproportionation by modifying Ni with Au. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.