Synthesis and characterization of highly active and coke resistant Ni/SBA-15 catalysts for dry reforming of methane

A series of newly-developed Ni/SBA-15 catalysts were synthesised by combining strong electrostatic adsorption (SEA) of [Ni (En)3]2+ (En = ethylenediamine), [Ni (NH3)6]2+ and [Ni (EDTA)]2- complexes, respectively, and engineered SBA-15 supports, or, in other words, by adopting Charge Enhanced Dry Impregnation (CEDI), to produce highly active catalysts with very small nickel particles, resistant to carbon deposition, sintering and deactivation phenomena associated with nickel based catalysts in dry reforming of methane (DRM). In parallel, other Ni/SBA-15 catalysts were prepared by conventional incipient wetness impregnation method with [Ni (H2O)6]2+ complex and used as the reference catalysts. TEM, wide-angle XRD, EDX, TGA results, and temperature programmed experiments confirmed that the catalyst’s preparation method has a strong impact on the size of the generated nickel particles and the amount of Ni deposited, which in turn were responsible for the catalytic activity and coke resistance. SEA on SBA-15 deposits from 4.8 wt% to 6.1 wt% Ni, depending on the complex used, while the DI deposits only 3 wt% of Ni. The size of resulting Ni particles is between 3 and 8 nm for the unwashed SEA samples. For the DI unwashed samples, the size is significantly bigger, at 20–50 nm. For the SEA washed samples before calcination, i.e., those synthesised by using [Ni (NH3)6]2+ and [Ni (En)3]2+ complexes, the Ni particle size is less than 1 nm. For these catalyst samples, only a small amount of carbon was deposited during the DRM reaction as confirmed by TGA results, which indicated only 0.08 wt% and 0.13 wt% carbon deposition.