Structure–activity relationship of an A-site-doped LaNiO3/SiO2 catalyst

Improving the anti-carbon deposition and anti-sintering ability under the premise of maintaining high catalytic activity is the core issue of Ni-based catalysts applied in CO methanation reactions. To address this issue, a La0.75A0.25NiO3/SiO2 (A = Ce, Sr, Sm, and Ca) catalyst is prepared via a citric acid complexation method. XRD results show that the substituted elements (Sr, Sm, and Ca) enter the LaNiO3 lattice and partially replace the A-site element La. The reduced Ni0 is beneficial to improve the medium temperature activity of the catalyst. The substitution of different elements produces different electronic effects that significantly affect the size of the Ni particles and the interaction between Ni and La2O3. The catalyst with doped Ca2+ as the A-site substituted element demonstrates better adsorption, storage, and migration capabilities for oxygen due to the lattice distortion that easily produces oxygen vacancies. Catalysts doped with Sr, Sm, and Ca as the A-site substituted element produce La2O2CO3 after the reactions, which plays a role in eliminating carbon deposits.

Kinetic Study on CO-Selective Methanation over Nickel-Based Catalysts for Deep Removal of CO from Hydrogen-Rich Reformate

The CO-selective methanation process is considered as a promising CO removal process for compact fuel processors producing hydrogen, since the process selectively converts the trace of CO in the hydrogen-rich gas into methane without additional reactants. Two different types of efficient nickel-based catalysts, showing high activity and selectivity to the CO methanation reaction, were developed in our previous works; therefore, the kinetic models of the reactions over these nickel-based catalysts have been investigated adopting the mechanistic kinetic models based on the Langmuir chemisorption theory. In the methanation process, the product species can react with the reactant and also affect the adsorption/desorption of the molecules at the active sites. Thus, the kinetic parameter study should be carried out by global optimization handling all the rate equations for the plausible reactions at once. To estimate the kinetic parameters, an effective optimization algorithm combining both heuristic and deterministic methods is used due to the large solution space and the nonlinearity of the objective function. As a result, 14 kinetic parameters for each catalyst have been determined and the parameter sets for the catalysts have been compared to understand the catalytic characteristics.

Ru nanoparticles supported on amorphous ZrO2 for CO2 methanation

The influence of support materials and preparation methods on CO₂ methanation activity was investigated using Ru nanoparticles supported on amorphous ZrO₂ (am-ZrO₂), crystalline ZrO₂ (cr-ZrO₂), and SiO₂.

Physical mixing of TiO2 with sponge nickel creates new active sites for selective CO methanation

Ni–α-Al₂O₃, Ni–SiO₂, Ni–γ-Al₂O₃, Ni–TiO₂, and Ni–ZrO₂ were prepared by physical mixing of metal oxides with sponge Ni, and the effect of physical contact of the metal oxides with sponge Ni on selective CO methanation was examined.

Mechanistic study and catalyst development for selective carbon monoxide methanation

As for selective CO methanation over heterogeneous catalysts, numerous investigations of the reaction mechanism and catalyst development are reviewed.

High catalytic performance of mesoporous zirconia supported nickel catalysts for selective CO methanation

Ni/mesoporous ZrO₂, without precious metals, exhibits high performance for selective CO methanation at a wide range of working temperatures and superior long-term stability.