Ethane dehydrogenation over the single-atom alloy catalysts: Screening out the excellent catalyst with the dual descriptors

摘要

Single atom alloys (SAAs) catalysts become potential to provide excellent activity, selectivity, and stability toward the selective dehydrogenation of light alkanes by activating the desired C-H bond, however, the ideal metallic combination to best catalyze C2H6 dehydrogenation is unclear yet. In this study, the activity and selectivity of ethane dehydrogenation on fifteen types of SAA catalysts (Co, Ir, Ni, Pd and Pt doped-Cu, Ag and Au) were fully investigated using DFT calculations and microkinetic modeling, and compared with that on the widely reported Pd, Pt, Cr and Pt3Sn. The results show that the activity of C2H6 dehydrogenation to gas phase C2H4 on all considered SAA catalysts has a relationship with C2H4 desorption energy, the easier the desorption of C2H4 is, the lower the activity of C2H6 dehydrogenation to gas phase C2H4 is. Similarly, C2H4 selectivity has a relationship with C2H5 adsorption energy, the weaker C2H5 adsorption energy is, the higher C2H4 selectivity is. Essential reason was explained based on the analysis of electronic properties. Thus, the dual descriptors, C2H4 desorption energy and C2H5 adsorption energy, were proposed to evaluate the activity and selectivity of C2H6 dehydrogenation to gas phase C2H4, respectively. Among these SAA catalysts, the low cost NiCu catalyst with the best activity and selectivity toward gas phase C2H4 formation is screen out, which is superior to the noble metals Pd and Pt widely reported. This study is expected to provide a simple and valuable method to screen out high performance SAA catalysts in alkane dehydrogenation to alkene.