Electronic interaction between Cr3+ ions in chromia-alumina catalysts for light alkane dehydrogenation

In this work chromia-alumina catalysts have been studied by the electron paramagnetic resonance (EPR) spectroscopy in the temperature range-120-200 ?. It was observed, that the activity of the catalysts in the dehydrogenation of n-butane and i-butane correlates with the amount of strongly interacting Cr3+ ions of the amorphous chromia phase. A disproportionate increase in the antiferromagnetic coupling energy delta E between Cr3+ ions was shown in the concentration range 4.7-9.8%wt.Cr (from 210 to 420 cm(-1)) and 9.8-13.3%wt.Cr (from 420 to 450 cm(-1)). It was established, that an increase in the exchange interaction between Cr3+ ions is more favourable for the dehydrogenation of i-butane as compared to n-butane.

Automated summary

In this study, chromia-alumina catalysts were investigated using EPR spectroscopy. The activity of the catalysts in dehydrogenation reactions was found to be correlated with the amount of Cr3+ ions in the chromia phase. The increase in antiferromagnetic coupling energy between Cr3+ ions with concentration was shown, indicating that the exchange interaction between Cr3+ ions is more favorable for the dehydrogenation of i-butane compared to n-butane.