Acidity-attenuated heteropolyacid catalysts: Acidity measurement using benzonitrile-TPD and catalytic performance in the skeletal isomerization of n-heptane

Difficulty in measuring acidic characters of heteropolyacid due to absorption of common bases such as ammonia and pyridine was circumvented using benzonitrile as an adsorbate. Acidity-attenuated and Pd-promoted heteropolyacid catalysts catalyzed n-heptane skeletal isomerization with high activity and high selectivity to branched heptanes, which are useful as clean high-octane fuels. Acidic characters measured by benzonitrile-TPD were well correlated with the catalytic performances.