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Design of earth-abundant Ni3ZnC0.7@Ni@C catalyst for selective butadiene hydrogenation

ABSTRACT

The pursuit of developing catalysts from earth-abundant materials to supplant those based on precious metals is of paramount importance in selective hydrogenations. While nickel-based systems have shown promise in the selective hydrogenation of butadiene, their practical applications are hampered by severe deactivation issues due to coke deposition and excessive hydrogenation. Here, a novel catalyst, Ni3ZnC0.7@Ni@C, is ingeniously engineered through the controlled oxidation of Ni3ZnC0.7@C. This catalyst is characterized by small Ni0 ensembles elegantly embellishing the Ni3ZnC0.7 nanoparticles, all encased within porous carbon shells. The evolutions of this catalyst, in terms of composition and structure during the oxidation process, is meticulously observed and characterized using a spectrum of advanced techniques. The Ni3ZnC0.7@Ni@C catalyst exhibits outstanding activity and stability in the hydrogenation of butadiene, surpassing other Ni-based systems, including its precursor Ni3ZnC0.7@C and other previously documented catalysts such as Ni3InC0.5 and the Ni3In alloy. A pivotal finding of this research is the self-limiting behavior of coke deposition in the initial reaction stages. This intriguing phenomenon not only curbs further deactivation but also significantly enhances butene production, maintaining operational stability for an impressive duration of 80 hours. This discovery underscores the advantageous role of in situ generated 'soft' cokes in augmenting the selectivity and stability of the catalyst, which is particularly enlightening for other catalytic processes that are similarly afflicted by coking issues, thereby opening avenues for further in-depth investigations in this field.