Influence of clay binder on the liquid phase hydroisomerization of n-octane over palladium-containing zeolite catalysts

The influence of the clay binder on the properties and performance of palladium-containing zeolite catalysts in the liquid phase hydroisomerization of n-octane was studied. Three different framework zeolites with similar Si/Al ratio were used as catalysts: USY, mordenite and beta with or without binder. 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. Moreover, the aluminium extraframework species (EFAL) created during the agglomeration process could cause a partial blocking of the micro-pore mouths, which would lead to an increase in the length of the effective diffusional pathway. After the agglomeration process, the monobranched isomers selectivity increased for all the samples while the multibranched isomers selectivity decreased. Due to the high pressure in the liquid phase, a significantly higher isomers selectivity was obtained as compared to vapour-phase conditions, and cracking became important only at relatively high average conversions. (c) 2006 Elsevier B.V. All rights reserved.