Mg-modified Ni-based catalysts prepared by the solution combustion synthesis for dry reforming of methane

Abstract

In the current work, nickel and magnesia containing catalysts synthesized by solution combustion synthesis (SCS) and impregnation were used for dry reforming of methane (DRM). The present research showcased the difference of two preparation methods and demonstrated the influence of temperature cycling and various duration on the activity of Ni-Mg catalysts (30 min, 10 h, 20 h, 200 h TOS). It was reported that Ni-Mg-Al catalysts exhibited mainly crystalline MgAl₂O₄ and nickel oxide in both fresh and spent catalysts confirmed by XRD results. As seen from TEM images, nickel particles ranged from 12 to 36 nm. Small metal particles indicate the strong interactions between the metal and the support. Moreover, these particles were localized at the tip of carbon nanotube indicating their activity. According to TPD, for all catalysts large amounts of basic sites and strong interactions between the metal and CO₂ were observed. Ni-Mg-Al obtained with SCS possesses 0.19 wt%·g⁻¹_Ni of carbon content, which was much lower than that of Ni-Mg catalyst. It was found that SCS derived Ni-Mg-Al catalyst exhibited higher activity compared to its reduced analogue prepared by impregnation. The former catalyst showed stable performance during 200 h test with a decreasing coking rate. The metal particle size was lower for this spent catalyst in comparison with Ni-Mg-Al tested for 20 h test.