Influence of lanthanide promoters on Ni/SBA-15 catalysts for syngas production by methane dry reforming

The catalytic performance of Ce- and La-promoted Ni/SBA-15 catalysts for syngas production from CO₂ reforming of methane has been investigated in a fixed-bed reactor at stoichiometric feed composition. Both promoted and unpromoted catalysts possessed high BET surface area of 303-445 m² g^-1. Additionally, SBA-15 support had a relatively uniform rod-like shape with a diameter of about 0.55 μm and a reduction in the crystallite size of NiO phase from 27.0 to 19.1 nm was observed with promoter addition reasonably due to the strong interaction between promoter and NiO particles. CeO₂ and La₂O₃ dopants were finely dispersed on catalyst surface. Temperature-programmed oxidation of spent catalysts showed that coke-resistance was improved significantly with promoter modification and 3%La-10%Ni/SBA-15 catalyst was the most resistant to carbonaceous deposition rationally due to the least NiO crystallite size hindering the nucleation and growth of graphitic carbon. Hence, La-promoted catalyst appeared to be the optimum catalyst in terms of reactant conversion, H₂ yield and stability whilst a gradual decline in both reactant conversion and H₂ yield was experienced with unpromoted and Ce-doped catalysts. Regardless of catalyst types, the ratio of H₂ to CO was always less than unity preferred for Fischer-Tropsch synthesis.