| Popis: |
Two preparation parameters, nickel concentration and molar ratio borohydride to nickel, strongly influence the activity of two series of NiB catalysts. The first series (classical P-2) is prepared by reduction of a Ni(II) ethanolic solution with sodium borohydride and the second one is derived from reversed micellar solutions of nickel carboxylates. In order to better understand the activity trends, we have analyzed the influence of these preparation parameters on the BET and metallic surface areas, on nickel and boron elemental compositions and on the particle size of these catalysts. For the metallic surface area, a method based on the hydrodesulfurization of thiophene was tested : this measurement was done in the liquid phase, on a catalyst which is therefore closer to its actual working conditions than in the gas chemisorption determinations. |
