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

Abstract

Abstract Carbon deposition is one of the major issues for catalytic methanation, especially when using high CO content syngas (such as H2/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 °C. With comprehensive characterizations by using BET, H2 chemisorption, H2-TPR, XPS, XRD, STEM, EDS, TEM, TG/DTA, Raman and TPH, we found that Au and Ni formed bimetallic nanoparticles of ∼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.