Characterizations and performances of Ni/diatomite catalysts for dry reforming of methane

•Diatomite heat treatment affects the type of carbon formed after test.•Ni/diatomite are good catalysts for dry reforming of methane.•Ni/MN3 deactivation mainly occurs by re-oxidation of nickel. Monometallic 5wt% Ni containing catalysts were prepared by a two-solvent (cyclohexane/water) deposition method using cheap and widely available natural diatomites (Ni/AW2 and Ni/MN3) as supports. The fresh samples were characterized by SEM, EDX microanalysis, N2 adsorption–desorption isotherms, XRD and tested after reduction (in hydrogen) in dry reforming of methane. Spent catalysts were further characterized by TPH coupled with mass spectrometry. Although slightly less active than a reference Ni/Aerosil (Ni/SiO2) catalyst prepared in similar conditions, the Ni/diatomites catalysts showed good activity with 90% methane conversion reached on Ni/MN3 at 800°C and a high selectivity towards dry reforming reaction (H2:CO molar ratio around unity over the entire temperature range). The catalysts were also relatively stable during catalytic measurements conducted at 650°C for 12h. In addition, depending on the nature of the diatomite and on the conditions of thermal activation, carbon deposits with lower toxicity (easier to remove by reactivation) than those formed on the Ni/Aerosil were obtained.