How to Translate the [LCu₂(H)]⁺‐Catalysed Selective Decomposition of Formic Acid into H₂and CO₂from the Gas Phase into a Zeolite.

Abstract

Translating a homogenous catalyst into a heterogeneous catalyst requires a fundamental understanding of how the catalyst “fits” into the zeolite and how the reaction is influenced. Previous studies of bimetallic catalyst design identified a potent copper homobinuclear catalyst, [(L)Cu2(H)]+ for the selective decomposition of formic acid. Here, a close interplay between theory and experiment shows how to preserve this selective reactivity within zeolites. Gas‐phase experiments and DFT calculations showed that switching from 1,1‐bis(diphenylphosphino)‐methane ligand to the 1,8‐naphthyridine ligand produced an equally potent catalyst. DFT calculations show that this new catalyst neatly fits into a zeolite which does not perturb reactivity, thus providing a unique example on how “heterogenization” of a homogenous catalyst for the selective catalysed extrusion of carbon dioxide from formic acid can be achieved, with important application in hydrogen storage and in situ generation of H2.

Decomposition of Copper Formate Clusters: Insight into Elementary Steps of Calcination and Carbon Dioxide Activation

“…[4] Hydride-based copper catalysts show a very distinct reactivity in organic chemistry and technology. [6] Furthermore, copper hydride based catalysts may play a key role in hydrogen storage applications. [6] Furthermore, copper hydride based catalysts may play a key role in hydrogen storage applications.…”

“…Structure of the hydride transfer transition state TS7 for reaction(6) along with the doubly occupied three-center σ(CuÀ HÀ C) and unoccupied σ* (CuÀ HÀ C) orbitals and the CHELPG charge of the transferred hydrogen atom. Calculated at the B3LYP/def2TZVP level of theory.…”

Models Facilitating the Design of a New Metal‐Organic Framework Catalyst for the Selective Decomposition of Formic Acid into Hydrogen and Carbon Dioxide

“…Although much progress has since been made in constructing a wide range of MOF catalysts, the vacuum like environment within MOFs suggested to us a tantalizing new concept for the design of novel MOF based catalysts, where gas‐phase studies are used to examine the likely reactivity of a catalytic metal site within a MOF (Scheme ). The use of gas‐phase models seemed plausible given that our previous reaction‐mechanisms approach, where gas‐phase studies using multistage mass spectrometry experiments (MS n ) in an ion trap are blended with DFT calculations, was successfully applied to the design of new catalysts from the ground up and the invention of new reactions for use in organic synthesis . In the former studies, through a sequence of iterations in which different ligands and metal sites were evaluated, we developed a series of ligated binuclear coinage metal hydride cationic catalysts for the selective decarboxylation of formic acid (Scheme a, b), a reaction of considerable interest for the use of formic acid in hydrogen storage applications .…”

“…Given the difficulty of establishing the nature of the solution phase catalyst, we were interested in translating the gas‐phase homogeneous catalysts into a heterogenous system. Unfortunately, the second generation catalyst 1 b was shown by DFT calculations not to fit into the framework of a ZSM‐5 zeolite, which resulted in the development of a new, less bulky catalyst 1 c based upon the N‐based 1,8‐naphthyridine ligand . This catalytic site was found to fit neatly into the framework a ZSM‐5 zeolite.…”

Intrazeolite CO Methanation by Small Ruthenium Carbonyl Complexes: Translation from Free Clusters into the Cage

“…This finding is in line with the recently reported translation of formic acid decomposition mediated by a ligated Cu 2 (H) + center in the same ZSM-5 pore. [19] Intrazeolite anchoring of [(napy)Cu 2 (H)] + was shown to lead to clear changes in the Mulliken charges, however the structure of the reactive Cu 2 (H) + center was maintained resulting in a mechanistic and energetically very similar reaction pathway for formic acid decomposition.…”