N2 as a co-soft oxidant along with CO2 in ethylbenzene dehydrogenation to styrene over γ-Al2O3 supported Co–Mo nitride catalysts

• First time nitride based catalysts are used in the ethylbenzene dehydrogenation.
• Compared to monometallic nitride, bimetallic nitride showed greater activity.
• CO2 co-feeding along with N2 over nitride based catalyst enhances the activity.
• Reverse water gas shift and ammonia synthesis reactions enhances activity.
• Neutralization of acidic sites by in situ generated NH3 maintains stable activity.

In addition to the key role played by CO2 as a soft oxidant in the dehydrogenation of ethylbenzene, N2 role as a co-soft oxidant is also significant particularly when Co–Mo based nitrides are used as catalysts. CO2 co-feeding along with a mild oxidant, N2 enhances the activity due to the reverse water gas shift reaction (due to CO2 participation), ammonia synthesis (due to N2 participation) and neutralization of surface acidic sites by ammonia generated during the reaction. The greater activity exhibited during dehydrogenation of ethylbenzene by Co–Mo nitride supported on γ-alumina when compared to the corresponding oxide catalyst is because of the removal of H2 through ammonia synthesis and neutralization of strong acidic sites by this ammonia, in addition to reverse water gas shift reaction. The catalysts are characterized by XRD, surface area and TPR.

Co-feeding of CO2 and N2 along with ethylbenzene over γ-Al2O3 supported Co3Mo3N catalyst results in higher yield of styrene due to participation of reverse water gas shift and ammonia synthesis reactions.Figure optionsDownload as PowerPoint slide