Dry reforming of methane at high space velocities on CeO2-supported Ni catalysts

High space velocities help to overcome diffusion limitations and achieve high throughput, features critical for scale-up. The performance of CeO2-supported Ni catalysts was evaluated for dry reforming of methane (DRM) at high space velocity (180,000 ml/gcat.hr) and extended time on stream (45 h) and compared with γ-Al2O3-supported Ni as a reference. Ni nanoparticles exhibited stronger metal-support interaction with CeO2 than γ-Al2O3. The catalysts were tested at 700 °C, 1:1 ratio of CH4/CO2, and atmospheric pressure. The average apparent CO2 reaction rate was higher for Ni/CeO2 catalysts than Ni/γ-Al2O3. Ni/CeO2 catalysts had lower H2/CO ratios of 0.4 – 0.55, while Ni/γ-Al2O3 was 0.6. The high CO2 reaction rate and low H2/CO ratio were due to the severe reverse water gas shift side reaction in Ni/CeO2 catalysts at high space velocities, which correlates with the oxygen vacancies in the support. DRM side reactions decreased the apparent CH4 reaction rate, an observation verified by thermodynamic calculations. The increased CO2 dissociative adsorption and oxygen radical migration in Ni/CeO2 catalysts lowered the carbon deposition rate (12 – 27 µg/gcat.min) compared to Ni/γ-Al2O3 (116.6 µg/gcat.min). Thiele-modulus (ϕ), effectiveness factor (η), and Weisz–Prater criterion (CWP) were used to confirm the absence of internal diffusion limitations in the catalysts under the reaction conditions. Ni/CeO2 catalyst is promising for scalable production of CO-rich syngas.