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Liquid-phase hydroisomerization of n-octane with three different framework zeolites catalysts with similar Si/Al ratios, USY, mordenite, and beta, was performed in a stirred batch autoclave microcatalytic reactor. As the hydrogenating-dehydrogenating function, platinum supported by impregnation (1 wt %) was used. Additionally, these zeolites were agglomerated with bentonite, the catalytic performance being compared with that obtained for the nonagglomerated samples. To characterize the catalysts, surface area measurements, temperature-programmed desorption of ammonia, atomic absorption spectroscopy, inductively coupled plasma emission spectrophotometry, hydrogen chemisorption, and solid-state 27Al NMR were used. In all cases, a decrease in the catalytic activity of agglomerated samples, because of the modification of the acidity and the porosity of the zeolites by the binder was observed. The decrease in the acidity after the agglomeration could be attributed to solid-state ion exchange between zeolite protons and clay sodium during the calcination of the catalyst. The binder also modified the porosity of the zeolite providing meso- and macropores, causing a partial blocking of the micropore mouths, which would lead to an increase in the length of the effective diffusional pathway. The presence of aluminium extraframework (EFAL) species in the agglomerated samples could also affect the catalytic performance. Due to the high pressure in the liquid phase, a significantly higher yield of isomers was obtained, and cracking became important only at relatively high average conversions. The maximum n-octane isomers yield obtained with all the nonagglomerated catalysts was very similar (about 75 mol %). This value was reached in 7.5 h for the beta-zeolite-based catalyst and in 10.5 and 23 h for the mordenite- and USY-zeolite ones, respectively.

The aim of this work was to study the influence of the reaction conditions in the hydroisomerization of n-octane over beta agglomerated zeolite, using platinum as the hydrogenating/dehydrogenating function. From the obtained data, a kinetic model was constructed to obtain the fundamental rate coefficients of the hydroisomerization reaction. The influence of the temperature was studied first, observing higher n-octane conversions with increasing temperature. The opposite effect was observed for the isomer selectivity. Next, it was observed that n-octane conversion decreased with the total pressure of the reaction, with the opposite effect being observed for the isomer selectivity. The effect of the reaction pressure in suppressing cracking and simultaneously promoting isomerization was attributed to the increase in the partial pressure of hydrogen. A similar effect was observed when the molar hydrogen/n-octane ratio was studied due to a better removal of alkenes species. When the influence of the contact time was studied, the conversion of n-octane increased as the contact time increased, while the selectivity to isomers decreased. It was observed that the ratio isomerized to cracked n-octane decreased as the contact time increased. Finally, the influence of the time-on-stream was studied, and no change in the time-on-stream runs of 30 h was observed. The n-octane hydroisomerization was simulated using a single kinetic model, based on a lumped reaction network for the main reaction. The excellent agreement between the experimental and calculated evolution of the different reaction parameters, as a function of the reaction conditions, was confirmed.