Particle Size Effects of Carbon Supported Nickel Nanoparticles for High Pressure CO2 Methanation

Supported nickel nanoparticles are promising catalysts for the methanation of CO2. The role of nickel particle size on activity and selectivity in this reaction is a matter of debate. We present a study of metal particle size effects on catalytic stability, activity and selectivity, using nickel on graphitic carbon catalysts. Increasing the Ni particle size from 4 to 8 nm led to a higher catalytic activity, both per gram of nickel and normalized surface area. However, the apparent activation energy remained the same (similar to 105 kJ mol(-1)). Comparing experiments at atmospheric to 30 bar pressure demonstrates the importance of testing under industrially relevant pressures; the highest selectivity is obtained at high CO2 conversions and pressures. Finally, the selectivity was particle size-dependent. The largest particles were not only most active but also most selective to methane. With this work we contribute to the ongoing debate about Ni particle size effects in CO2 methanation.

Automated summary

In this study, the effects of nickel particle size on catalytic stability, activity, and selectivity in CO2 methanation were investigated. Increasing the nanoparticle size led to higher catalytic activity, while the apparent activation energy remained the same. Testing at industrially relevant pressures revealed that the highest selectivity was achieved at high CO2 conversions and pressures, and the selectivity was dependent on particle size, with larger particles being more active and selective towards methane.