Tri-reforming of Methane over a Hydroxyapatite Supported Nickel Catalyst

For the first time, a catalyst containing 5 wt. % Ni supported on a hydroxyapatite support (HAP) has been synthesized and evaluated in tri-reforming of methane (TRM) for synthetic gas (syngas) production. Nickel nanoparticles could be easily formed on HAP surface by using the conventional incipient wetness impregnation technique. In TRM, under unfavorable reaction conditions from the thermodynamic point of view (e. g. medium reforming temperature of 700-800 degrees C, low steam-to-carbon ratio, etc.), this catalyst showed high methane conversion (up to 90 %), however, some deactivations took place. The latter could be explained by both the thermal sintering of nickel nanoparticles and the solid carbon formation. The impact of the main operational parameters has been studied. Increasing the reaction temperature, the molar ratios of oxygen-to-carbon and steam-to-carbon are favorable for the methane conversion and mostly for the stability of the catalyst. High methane conversion of ca. 90 % with a perfect catalytic stability during 300 hours-on-stream could be achieved at 800 degrees C and 1.4 bar, using a mixture containing low ratio of oxidant-to-carbon (molar ratio of CH4/CO2/H2O/O2/N2=1.0/0.67/0.9/0.1/0). These results offer the opportunity to further design an optimal Ni/HAP catalyst by improving metal-support interaction and downsizing nickel nanoparticles. For the first time, hydroxyapatite supported nickel catalyst has been investigated in tri-reforming of methane for syngas production. Excellent activity, selectivity and stability could be achieved under unfavorable reaction conditions of methane reforming. image