Catalytic performance of pelletized Ni-UGSO in steam methane reforming at elevated pressures

This study examines the performance of a Ni-UGSO catalyst for steam methane reforming under elevated pressure. The catalyst achieved near-equilibrium methane conversion at 11 bar and 820 °C with a steam-to-carbon ratio (S/C) of 2. Nickel supported on UGSO (upgraded slag oxides) pellets maintained stable activity within S/C = 1.7–2 at a gas hourly space velocity (GHSV) of 1000 L h⁻¹ kgcat⁻¹. However, operation under lower steam conditions (S/C ≤ 1.5) led to surface pitting and the growth of bamboo-type carbon filaments, resulting in catalyst deactivation. After regeneration, the catalyst recovered its surface morphology and catalytic activity, achieving 80 % methane conversion and an H₂/CO ratio of 5.45 at 10 bar and 820 °C. The strong interaction between nickel and the spinel–silicate matrix minimised sintering and enhanced lattice oxygen mobility, as evidenced by the presence of NiOOH and FeOOH species, as determined by various characterisation techniques. These findings confirm the structural stability and regenerability of Ni-UGSO pellets for sustained high-pressure syngas production. • Silicates and spinels in Ni-UGSO pellets improve coke gasification reactions in MSR. • Pellets containing 13 % Ni and 25 % clay produced improved results. • Negligible coke deposition was observed at S/C=2, 10 bar, and 820 °C for 49 h.