Exploring the mechanisms of aqueous methanol dehydrogenation catalyzed by defined PNP Mn and Re pincer complexes under base-free as well as strong base conditions

Zhihong Wei, Adiran De Aguirre, Kathrin Junge, Matthias Beller, Haijun Jiao

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

The mechanisms of aqueous methanol dehydrogenation reaction [CH3OH + H2O = 3H2 + CO2] catalyzed by conjugated PNP pincer amido M(CO)2(PNP) and amino HM(CO)2(PNHP) complexes [M = Mn, Re; and PNP = N(CH2CH2P(isopropyl)2)2] under base-free and strong base conditions as well as the K+ promotion effect were studied at the B3PW91 level of density functional theory. Benchmark calculations including dispersion and/or solvation corrections validated the computed gas phase data to be closest to the available kinetic and thermodynamic data from experiments. Under base-free conditions, the innocent mechanism is kinetically more favorable than the non-innocent mechanism. Under strong base conditions, KOH plays a dual role: deprotonating the substrate by OH- and stabilizing the rate-determining transition state by K+ by lowering the free energy barrier for H2 formation by N⋯K+⋯O interaction. Considering the special role of formic acid in H2 storage and CO2 hydrogenation, formic acid dehydrogenation should be accessible under base-free and strong base conditions.

Original languageEnglish
Pages (from-to)3649-3665
Number of pages17
JournalCatalysis Science and Technology
Volume8
Issue number14
DOIs
StatePublished - 2018
Externally publishedYes

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