Highly coke resistant Ni–Co/KCC-1 catalysts for dry reforming of methane.

Nanofibrous KCC-1 supported Ni–Co bimetallic catalysts were investigated for dry reforming of methane for syngas generation. Monometallic catalysts such as Ni/KCC-1 and Co/KCC-1, and a series of bimetallic Ni–Co/KCC-1 catalysts were prepared by impregnation and co-impregnation method, respectively. All the catalysts were characterized by XRD, FT-IR, HR-SEM, FE-SEM, XPS, FT-Raman, BET, UV–Visible DRS and AAS techniques. Monometallic nickel supported catalyst contains NiO as an active phase, whereas bimetallic nickel catalysts contain Ni 2 O 3 , and NiCo 2 O 4 on the surface. In the case of cobalt loaded catalysts, spinel Co 3 O 4 is the dominant active species, apart from NiCo 2 O 4. The addition of cobalt in Ni/KCC-1 has a pronounced effect on the crystallite size, surface area and active species. The hydrogen pretreatment of the catalyst produces bimetallic Ni–Co alloy on the surface. The catalytic activities of the bimetallic catalysts towards dry reforming of methane are better than monometallic catalysts. Mesoporous silica-based KCC-1 offers easy accessibility to the entire surface moieties due to its fibrous nature and the presence of channels, instead of pores. The 2.5%Ni-7.5%Co/KCC-1 showed the maximum CH 4 and CO 2 conversion along with a remarkably low H 2 /CO ratio. The life-time test confirms the high thermal stability of the catalysts at 700 °C for 8 h, with less deactivation due to coke formation. The spent catalysts were characterized by XRD, TGA, FT-Raman, and FE-SEM to understand the structural and chemical changes during the reaction. The insignificant D band and G band of graphitic carbon in FT-Raman spectra for the highly active 2.5%Ni-7.5%Co/KCC-1 and 5%Ni–5%Co/KCC-1 catalysts along with TGA results containing 12% weight loss confirms the minimum coke deposition, formation of amorphous carbon and highest coke resistance. The fibrous support restricts the sintering and aggregation of nickel particles as well the deposition of coke. The addition of amphoteric cobalt increases the activity and stability of the catalysts. Ni–Co/KCC-1 with high coke resistance seems to be a promising catalyst for dry reforming of methane. [Display omitted] • Ni–Co/KCC-1 was synthesized by sol–gel-hydrothermal and co-precipitation method. • Cobalt addition in Ni/KCC-1 catalyst suppressed the aggregation of Ni particles. • Bimetallic Ni–Co/KCC-1 catalysts are more coke resistant than monometallic KCC-1. • 2.5%Ni-7.5%Co/KCC-1 showed the highest CH 4 and CO 2 conversion, and a low H 2 /CO ratio. • Bimetallic catalysts improved the catalytic performance by reducing coke deposition. [ABSTRACT FROM AUTHOR]