An entropy engineering strategy to design sulfur-resistant catalysts for dry reforming of methane

Abstract

The real-world conditions for dry reforming of methane (DRM) inevitably involve the presence of sulfur-containing compounds. Therefore, a general principle for designing sulfur-resistant catalysts is highly desired for the DRM process. In this work, driven by lower Gibbs free energy via entropy engineering, the high-entropy NiAl2O4-type catalyst {(Ni3MoCoZn)Al15Ox} is synthesized by a mechanochemical ball milling process. The DRM performance of the high-entropy catalyst was tested before and after being sulfided by SO2, and compared with those of the control catalysts. Various techniques such as XPS, HAADF-STEM, SO2-TPD, TGA-DSC, FTIR, and DFT theoretical calculations are utilized to reveal the mechanism of sulfur resistance in the high-entropy catalyst. The results indicate that the formation of crystalline high-entropy oxides in the (Ni3MoCoZn)Al15Ox, with its relatively higher configurational entropy, protects itself from SO2 poisoning. This contributes to superior SO2 tolerance compared to the control (Ni3)Al18Ox, and thus offers better DRM stability than the control binary, ternary, or quaternary catalysts after pre-sulfurization. The key essence of sulfur resistance lies in the lower adsorption energy of SO2 on the high-entropy catalyst. This high-entropy stabilization towards an anti-sulfur strategy may inspire the design and development of sulfur-resistant catalysts for catalytic applications in the near future.