Highly active and stable Ni/SBA-15 catalysts prepared by a “two solvents” method for dry reforming of methane

Abstract

Two series of Ni (2.5 to 7.5 wt%) and Ce (6 wt%) containing SBA-15 catalysts were prepared and tested in dry reforming of methane, a promising route for the production of syngas. Both Ni and Ce species were introduced in the organized mesoporous silica support in the form of nitrate salts using the "two solvents" procedure that is known to favor metal dispersion inside the porosity. Samples characterizations by N 2 sorption, SAXS, XRD, SEM and TEM indicate good preservation of the porosities after Ni deposition and calcination as well as formation of NiO nanoparticles entrapped in the porous channels. In the cerium-enriched samples, the CeO 2 nanoparticles are also highly dispersed. After reduction, all the catalysts show high activity and selectivity towards H 2 and CO at atmospheric pressure with full CH 4 conversion below 650 o C. In these conditions, there is no significant promotional effect by ceria. Moreover, prolonged tests performed at 500 o C for 12 hours reveal a high stability of the catalysts. The absence of deactivation throughout the catalytic run at this temperature agrees with the low carbon amount detected after test and with the limited sintering of the Ni nanoparticles in the used catalysts. The positive effect of the SBA-15 mesoporous channels towards stabilization of the supported particles is discussed.

Recent Scientific Progress on Developing Supported Ni Catalysts for Dry (CO2) Reforming of Methane

“…It resulted in better dispersion of small Ni nanoparticles with narrower size distributions compared to the respective one prepared by classical impregnation method without using chelating ligands (Figure 7) [82]. The prepared catalysts showed stable catalytic activity towards DRM at 750 • C for 40 h and the size of Ni particles inside pores of SBA-15 silica was confined by pore structures of parent supports [82]. Reprinted with permission from Ref.…”

“…Kang et al used a polyethyleneimine (PEI) as a chelating ligand of Ni precursors during impregnation processes [82]. Ni-PET complexes were well distributed inside the pores and strongly bound the SBA-15 silica surface through the strong interaction between NH 2 terminal groups of PEI and surface silanol groups of silica.…”

“…Although utilization of ligand during the impregnation method can improve dispersion of Ni nanoparticles inside the pore structure of supports, it has been reported that the formation of some Ni particles outside of pores during wet-chemical processes is still not avoidable, which are subject to aggregation during the DRM reaction [82,83]. Alternatively, small Ni nanoparticles can be embedded inside pores of porous supports using dry-methods.…”

Ordered mesoporous “one-pot” synthesized Ni-Mg(Ca)-Al2O3 as effective and remarkably stable catalysts for combined steam and dry reforming of methane (CSDRM)

“…For SRM and DRM catalysts, it was recently found that confinement of the nickel active phase within structured pores of oxide supports, especially mesoporous silica [40][41][42] or alumina [43][44][45][46], helps minimizing Ni 0 sintering during reaction, thus preserving reactivity with time on stream.…”

Effect of pore geometry of mesoporous supports on catalytic performances in methane reforming

“…Recent studies have shown that mesoporous SBA-15 silica support is promising for the confinement and stabilization of nickel in DRM reaction [10,11]. The addition of ceria to Ni/SBA-16 catalysts was studied by Zhang et al [12] and the results showed that NiCe/SBA-16 was more stable, exhibiting higher conversion than Ni/SBA-16 in DRM.…”