Methane

Catalysis

Adsorption

Methanation

Materials science

Inorganic chemistry

Geology

Atmospheric pressure

Oceanography

Physical chemistry

Lanthanum

Hydrogen

Physics

Organic chemistry

Environmental science

Chemistry

Incipient wetness impregnation

Selectivity

Meteorology

Space velocity

Atmospheric temperature range

Applied Catalysis B Environment and Energy

Ni/La-γ-Al2O3 samples containing 13.6 wt.% Ni and a variable amount of lanthana (0, 4, 14 and 37 wt.%) were prepared by incipient wetness impregnation, using silica-free γ-Al2O3 support. The materials were characterized, as such or after reaction, with XRD, H2-TPR, IR, UV–vis-NIR, XPS and FE-SEM techniques. They were tested as catalysts for CO2 methanation at atmospheric pressure at GHSV 55000 h−1. The reaction is under kinetic control at T < 650–673 K, while the product mixture is under thermodynamic control above this temperature range. Lanthanum addition strongly increases the activity of Ni/γ-Al2O3 for CO2 methanation. Methane selectivity is increased to nearly 100% at low temperatures (T < 650 K). The CO2 methanation reaction on La-doped Ni/γ-Al2O3 occurs with similar activation energies (80 kJ/mol), and with slightly higher reaction order for hydrogen and lower reaction order for CO2 than those observed for undoped Ni/γ-Al2O3. Lanthanum acts as a promoter because of the stronger basicity of the lanthana-alumina support allowing stronger adsorption of CO2 as surface carbonates that can be act as “reactant reservoirs”. The Ni/La-alumina catalysts studied here are similarly effective as Ru/alumina catalysts for the selective CO2 methanation at low temperature and atmospheric pressure.

A study of Ni/La-Al2O3 catalysts: A competitive system for CO2 methanation