A highly active and chemoselective assembled Pt/C(Fe) catalyst for hydrogenation of o-chloronitrobenzene

A highly active and chemoselective assembled Pt/C(Fe) catalyst was prepared by an adsorption protocol. Pt nanoparticles (∼2.4 nm) in a Pt colloid solution obtained from the decomposition of Pt2(dba)3 (dba = dibenzalacetone) were utilized as Pt precursors and adsorbed by Fe-modified active carbon (AC). The adsorption method makes Pt nanoparticles enriched on the surface of the catalyst, and the enrichment was further enhanced due to the presence of Fe in the active carbon, leading to the formation of more active sites exposed on the surface. XPS analysis revealed that a much more electron-deficient state of the Pt nanoparticles was existed due to the electron transfer between Pt nanoparticles and Fe2O3. This catalyst was used for the liquid phase hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) with the highest turnover frequencies (TOF) of 78 (molo-CNB/(molPt s)) and a selectivity of 99.5% at complete conversion of o-CNB. The catalyst was also recycled for five times and the total turnover number was more than 625,000 (molo-CNB/molPt).

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► A novel absorption protocol for synthesis of assembled Pt nanocomposite catalyst has been established.
► The hydrogenation TOF was 78 s−1 when the selectivity of 99.5% to o-CAN was obtained at a complete conversion.
► The catalyst exhibited remarkable activity for five consecutive recycles.
► The absorption protocol and the modification of AC by Fe both play decisive roles on the catalytic properties of the catalyst.