Development of Nickel Catalysts for CO2 Methanation – Investigating the Effect of Support and Synthesis Method

One approach to mitigate climate change is the reduction of atmospheric CO₂ via CO₂ conversion into useful chemicals. CO₂ conversion by hydrogenation to methane is catalyzed by heterogeneous Ni-based catalysts. For these catalysts, the support has been reported to have an impact on catalytic performance; we seek to understand these support effects in order to design better catalysts. In this work, we have synthesized a series of Ni nanoparticle catalysts using several synthesis methods to investigate how the support choice and synthesis parameters influence the structure and the effectiveness of the catalyst. Ni catalysts were prepared on SiO₂, mesoporous silica (SBA-15), Al₂O₃, TiO₂, and CeO₂ supports. These catalysts were made by incipient wetness impregnation (IWI), strong electrostatic adsorption (SEA), or colloidal synthesis of nickel nanoparticles. The resulting catalysts were characterized by H₂ or CO chemisorption and TEM to determine the impact of support and method on Ni particle size. Ni/SBA-15 prepared by SEA had the highest dispersion of the studied materials. Furthermore, during the methanation reaction, the Ni/Al₂O₃ prepared by SEA had the highest CO₂ conversion rate. With the goal of preparing uniform sized Ni particles across the series of supports, we prepared colloidal Ni particles which were found to be 3.16±0.5 nm as prepared. Once deposited onto the supports, however, we determined that the Ni/SiO₂ particles were much larger than the Ni/TiO₂ particles. Ongoing work is investigating alternative approaches to maintain uniform Ni particle size across the series of supports. From this study, we have made advancements in our ability to utilize support materials to improve catalysts for CO₂ conversion and other reactions.