Pt/MgO catalysts intrinsically promoted by fast moving bed pyrolysis for hydrogenation properties

Abstract

Elucidating the correlation between the geometric/electronic structure of the catalyst and its catalytic performance is of paramount importance. However, achieving precise manipulation over the geometric/electronic structure of the catalyst remains a formidable challenge. Here, we develop a fast moving pyrolysis bed (FMPB) strategy to finely regulate the geometry structure (Pt metal particle size and Pt-O coordination number (CN)) and electronic structure of the Pt/MgO catalyst. It is found that the hydrogen dissociation energy barrier is negatively related to the Pt atom electron density. The Pt1/MgO-600-N2 (600 and N2 represented the temperature and atmosphere under fast pyrolysis, respectively) with highest electron density exhibits the highest para-chloronitrobenzene (p-CNB) hydrogenation activity (66978 h−1), which is ∼220 times that of Pt nanoparticles (NPs, Pt NPs/MgO), ∼58 times that of Pt1/MgO-400-air, and ∼3 times that of Pt nanoclusters (NCs, Pt NCs/MgO). DFT calculations disclose that Pt1/MgO-600-N2 with highest Pt-5d center, which is more conducive to hydrogen dissociation. The transition of the H2 cleavage mode from homolytic (Pt NPs/MgO) to heterolytic (Pt1/MgO-600-N2) makes it more favorable for the hydrogenation of the polar nitro functional group, ensuring that substantial enhancement in its activity while preserving high selectivity in hydrogenation.