Influence of the template on the properties of SAPO-31 and performance of Pd-loaded catalysts for n-paraffin isomerization

The SAPO-31 silicoaluminophosphates were synthesized by using different di-alkylamines and their properties were characterized by XRD, SEM and N2 adsorption. NH3-TPD, IR spectroscopy of adsorbed pyridine and 29Si MAS NMR showed that these molecular sieves differed in their acidity both in the number of acid sites and in their strength. The catalytic properties of Pd/SAPO-31 samples were compared in n-decane conversion. It was found that their activity was related to the acidity of SAPO-31, but the isomerization selectivity was defined by the structural characteristics of the microporous material with minor influence of the other physico-chemical properties studied.

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► Phase pure SAPO-31 samples were synthesized by using different di-alkylamines.
► Different crystallinity, crystal size, adsorptive and acidic characteristics.
► Activity of Pd/SAPO-31 was different and influenced by their acidic properties.
► Isomerization selectivity of the catalysts at equal activity was similar.