Nonoxidative light alkane dehydrogenation is a profitable approach to produce olefins, the building blocks for numerous applications in the chemical industry. The discovery of active and selective catalysts plays a critical role in reducing the energy imput required in dehydrogenation processes of natural gas. Herein, we applied a multiscale computational approach, combining Density Functional Theory (DFT), microkinetic modeling (MKM), and ab initio molecular dynamics (AIMD) to investigate the catalytic behavior of aluminum-based catalysts doped with heterometals. DFT calculations revealed a gamut of different dehydrogenation pathways and demonstrated that heterometal (e.g. Ga) doping reduces the overall dehydrogenation barrier of the most favored concerted mechanism (simultaneous activation of two C-H bonds). Interestingly, upon combining all dehydrogenation mechanisms into a single composite mechanism, MKM revealed that the stepwise pathways (sequential activation of two C-H bonds) are responsible for producing more than 99% of olefins on both pristine and dopped systems. Since hydrogen atoms bind strongly the Lewis acid-base sites on the catalyst surface, AIMD simulations were performed to probe the feasibility of forming molecular H2 at typical dehydrogenation conditions. The AIMD simulations revealed that the catalysts can convert surface-bound hydrogen into molecular H2 at 873.15 K, limiting the effect of hydrogen poisoning on dehydrogenation activity. Finally, our detailed computational study identifies novel Al-based catalytic systems as efficient dehydrogenation catalysts of light alkanes into valuable olefins and reveals highly complex alkane dehydrogenation mechanisms.

Multiscale modeling for the discovery of active alkane dehydrogenation catalysts

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