Metal-Phosphate catalysts properties for biofuel production
Résumé
Biogas reforming allows obtaining synthetic gas (syngas) under adequate conditions of temperature and pressure. A solid catalyst must generally be used to have exploitable reaction kinetic. At the industrial scale, steam methane reforming has largely been deployed to reform natural gas. However, this process is strongly energy-consuming since it works with a high steam-to-carbon ratio (S/C close to 3.5/1) to keep the catalyst stable over long reaction time. The objective of this work is to develop an efficient catalyst for the reforming of methane at low S/C ratio (i.e. close to the stoichiometry). Calcium hydroxyapatite (Ca10(PO4)6(OH)2) – or HAP – has recently been investigated as catalyst support for the dry reforming of methane (DRM) reaction. Very promising results have been obtained [1]. By controlling the molar ratio of Ca to P, the acido-basicity of this support can be adjusted which is a crucial factor for CO2 adsorption and dissociation. This support is also well known by its high thermal stability as well as its good ionic exchange capacity for divalent metals such as nickel and cobalt. In this work, DRM reaction over HAP-based catalysts has been studied. HAP support was synthesized from calcium carbonate (CaCO3) or calcium nitrate (Ca(NO3)2) as calcium sources and ammonium dihydrogen phosphate (NH4H2PO4) as phosphate source. Different monometallic or bimetallic catalysts containing Ni and/or Co were prepared and evaluated in DRM reaction. Different physico-chemical characterizations such as metal-support interaction, acid-base nature, surface area, support porosity etc. were also carried out to link the catalytic performance with the properties of the prepared catalysts.
