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Download fileRevealing the Effect of Sodium on Iron-Based Catalysts for CO2 Hydrogenation: Insights from Calculation and Experiment
journal contribution
posted on 2021-04-02, 07:13 authored by Xianglin Liu, Chao Zhang, Pengfei Tian, Minjie Xu, Chenxi Cao, Zixu Yang, Minghui Zhu, Jing XuThe promotional effects of sodium
on Fe5C2 catalysts for CO2 hydrogenation
were systematically investigated
by a synergistic combination of density functional theory (DFT) calculations
and experimental methods. Na was found to markedly alter the electronic
structure of Fe5C2 surface, leading to a reduction
of the CO2 dissociation barrier from 0.45 to 0.08 eV and
a decrease of the hydrogen binding energy. Moreover, Na lowers methane’s
selectivity by hindering further hydrogenation of CH2 and
enhances C–C coupling probability by promoting the chain growth
of CH2. Additionally, Na strengthens alkenes’ selectivity
by facilitating dehydrogenation of alkyls and boosting the desorption
of alkenes. The theoretical findings were confirmed by experimental
results. Adding Na to Fe5C2 catalyst was found
to facilitate CO2 conversion and alkenes’ selectivity.
Especially, the O/P (olefin/paraffin) ratio of C2–C4 hydrocarbons increases from 2.0 to 9.7 and the C5+ hydrocarbons’ selectivity increases from 12.6% to 51.8%.
This study further deepens the understanding of the promotional effect
of sodium on Fe-based catalysts for CO2 hydrogenation and
enlightens the rational design of highly selective catalysts.