Bulk and γ-Al2O3-supported Ni2P and MoP for hydrodeoxygenation of palmitic acid

The use of a series of bulk and supported Ni2P and MoP materials in the hydrodeoxygenation of palmitic acid, shows that their catalytic performance can be tuned by the presence of Al2O3 as a support. Al2O3 promotes acid-catalyzed pathways, and influences the phosphide functionality. A series of strategies can be followed to successfully decrease the phosphide particle size, i.e., the use of citric acid (applied to bulk Ni2P), and the use of low reduction temperatures (applied to Ni2P/Al2O3) during the preparation steps. The effects of synthesis parameters and the support on the properties of the phosphides were determined by, e.g., X-ray diffraction, transmission electron microscopy, BET analysis, CO adsorption and NH3-TPD. Small particle size of phosphides does not necessarily lead to a large exposed surface of metal phosphide due to residual carbon or to agglomeration of phosphide particles. The specific activities (per gram of material) follow the trend MoP/Al2O3-TPR (high temperature synthesis) C15H31CHO -> C16H33OH -> C16H34; decarboxylation/decarbonylation (DCO): C15H31COOH > [C15H31CHO] -> C15H32; and esterification: C15H31COOH + C16H33OH -> C15H31COOC16H33. The presence of Al2O3 increases the esterification rates due to relative high acidity, and makes the supported Ni2P phase more selective towards CC bond cleavage than bulk Ni2P or MoP/Al2O3-TPR. (C) 2015 Elsevier B.V. All rights reserved.