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The influence of the binder on the properties and performance of palladium-containing zeolite catalysts in the n-octane hydroisomerization was studied. Three different framework zeolites were used as catalysts:  mordenite, β, and ZSM-5 with or without binder. 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. Catalytic performance of the zeolites was strongly influenced by the binder because its presence modified both zeolite acidity and porosity. A decrease in the strong acidity of the zeolites could be observed when the samples were agglomerated, due to a solid-state ion exchange between the zeolite protons and bentonite sodium. The neutralization of some zeolite acid sites caused a decrease in the n-octane conversion for mordenite (from 90.5 to 53.8 mol %) and ZSM-5 (from 78.4 to 71.2 mol %) zeolites. The binder modified the porosity of the zeolite providing meso- and macropores, which allow a higher formation of branched isomers for mordenite (from 27.3 to 48.9 mol %) and ZSM-5 (from 14.3 to 35.4 mol %). Activity of β zeolite was modified by the presence of extraframework aluminum species (EFAL) formed during the agglomeration process, improving both n-octane conversion (from 22.9 to 88.7 mol %) and branched isomer selectivity (from 48.7 to 77.5 mol %).

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The influence of the amount of two clay binders (montmorillonite and bentonite) on the acid properties and performance of Pd/HZSM-5 zeolite with different Si/Al ratios for the hydroisomerization of n-butane has been studied. Temperature-programmed desorption of ammonia, atomic absorption spectroscopy, chemisorption, and surface area measurements were used to characterize the catalysts. After agglomeration, some zeolite protons are neutralized by clay sodium and, consequently, a lower n-butane conversion is obtained. The product selectivity is also strongly influenced by the binder due to the fact that zeolite hydrogen transfer activity, metal/acid site balance, and diffusion of products are modified. If the appropriate binder is selected, the decrease in conversion will be compensated by a much higher isobutane selectivity. Thus, a catalyst based on Pd/HZSM-5, with a zeolite Si/Al ratio of 25, and agglomerated with bentonite in a zeolite/clay ratio of 35/65 wt/wt, showed not only an adequate mechanical resistance but also high isobutane selectivity and isobutane yield (87.1 and 23.9 mol %, respectively). It should be remarked that, under the same reaction conditions, the parent catalyst without binder showed worse isomerization activity (18.5 mol % isobutane yield with 47.3% isobutane selectivity).