Direct dehydrogenation of ethylbenzene over nickel phosphide/carbon nanotube hybrid catalyst: Mechanistic insight into phosphor as electronic structure regulator

Development of non-noble metallic catalysts for alkane dehydrogenation is a hot topic in the field of catalysis, which relies on the in-depth understanding of the reaction mechanism and the accurate engineering of the electronic structure of the catalyst. In the present work, a novel phosphor modified nickel based catalyst (NiPx/oCNT) was prepared and employed for direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The NiPx/oCNT catalyst with well-designed electronic structure showed ST formation rate at 3.19 mmol g−1 h−1 with over 99.0 % ST selectivity with a decent deactivation rate of 0.02 h−1. Comprehensive structure-function relationship characterizations and density functional theory calculations revealed that the electron density in d orbital of Ni decreased with the electronic structure regulation of phosphor, which effectively facilitated ST desorption and reduced the cracking side-reaction and consequent carbonous deposition. The present work not only developed a novel Ni-based catalyst for highly efficient EB DDH reactions but also testified an important concept of delicate electronic structure engineering for enhancing the catalytic performance of transition metal catalysts.