n-Hexadecane hydroisomerization over Pt-HBEA catalysts. Quantification and effect of the intimacy between metal and protonic sites

n-Hexadecane (n-C-16) transformation was carried out at 220 degrees C and 30 bar over bifunctional catalysts with Pt and HBEA as hydro-dehydrogenating and acid components. Three series of catalysts were prepared, with different levels of proximity between Pt and acid sites: in series 1, Pt was essentially located on the outer surface of HBEA crystal agglomerates of similar to 12.5 mu m, series 2 and 3 resulted from combination of Pt-Al2O3 and HBEA particles of similar to 70 mu m and from mechanical mixture of Pt-Al2O3 and HBEA particles of similar to 300 mu m, respectively. The rate and selectivity of n-C-16 hydroisomerization was shown to be determined by only two parameters, the balance between the metal and acid functions and their degree of intimacy. Both of them were easy to be quantified: the first one by the C-pt/CH+ ratio between the concentrations of accessible Pt and protonic sites, the second one by n(as), the number of acid steps undergone by olefinic intermediates during their diffusion between two Pt sites which can be drawn from the initial product distribution. (C) 2013 Elsevier Inc. All rights reserved.