Frustrated Lewis Pairs in Heterogeneous Catalysis: Theoretical Insights

Abstract

Frustrated Lewis pair (FLP) catalysts have attracted much recent interest because of their exceptional ability to activate small molecules in homogeneous catalysis. In the past ten years, this unique catalysis concept has been extended to heterogeneous catalysis, with much success. Herein, we review the recent theoretical advances in understanding FLP-based heterogeneous catalysis in several applications, including metal oxides, functionalized surfaces, and two-dimensional materials. A better understanding of the details of the catalytic mechanism can help in the experimental design of novel heterogeneous FLP catalysts.

Corrugation-Induced Active Sites on Pristine Graphene for H2 Activation

“…Catalysis by FLPs is a new and vibrant field. − The basic premise is that a sterically hindered Lewis acid and base pair can provide an active site that polarizes a molecule such as H 2 , leading to its dissociation and formation of protonic and hydridic species. , This FLP mechanism, originally suggested in homogeneous catalysis, has recently found numerous applications in heterogeneous catalysis. − Since an FLP typically consists of an electron-rich and an electron-poor species, , it is not immediately clear how Gr can provide FLPs.…”

Design and Synthesis of Heterogeneous Frustrated Lewis Pairs for Hydrogenation: From Molecular Immobilization to Defects Engineering

“…Meanwhile, it is also more conducive to the design and development of heterogeneous FLP catalysts. [24]…”

“…Understanding the interaction of Lewis acid and Lewis base, as well as the mechanism of FLP activation of hydrogen source, is crucial for the study of hydrogenation reaction over FLP catalysts. Meanwhile, it is also more conducive to the design and development of heterogeneous FLP catalysts [24] …”

Design of Frustrated Lewis Pairs by Functionalizing N-Doped Graphene Edge with Tunable Activity for H2 Dissociation

“…As far as our knowledge, the first case of constructing heterogeneous FLPs is reported by Sautet and co-workers, where the nonadjacent Al···O pairs on the γ-alumina surface with both strong acidity and basicity are highly active for the heterolytic splitting of both H 2 and CH 4 . , Subsequently, Singh and co-workers reported that the In···O FLPs constructed on hydroxylated indium oxide surface with oxygen vacancies can effectively catalyze H 2 dissociation and following CO 2 hydrogenation. − Recently, solid FLPs constructed by regulation of surface oxygen vacancies on reduced CeO 2 surfaces were proposed for hydrogen dissociation and methane conversion. ,, The enhanced FLP acidity and basicity together with the elongated distance of Ce···O pairs contribute to the high activity of the solid FLPs for hydrogen dissociation and acetylene hydrogenation . Besides oxide surfaces, − designing heterogeneous FLPs has been proved by various strategies and materials, , such as functionalizing metal–organic framework (MOF), ,, adsorbing molecules on solid surfaces − and doping two-dimensional materials. , Despite these significant advances in designing heterogeneous FLPs, metal elements are still indispensable for the construction of heterogeneous FLPs, which deviates from the initial metal-free concept of FLP catalysis . Therefore, it is imperative to develop metal-free heterogeneous FLPs which retain the high activity for hydrogen dissociation and match the original conception of FLPs as metal-free catalysts.…”

“…19,30,31 The enhanced FLP acidity and basicity together with the elongated distance of Ce•••O pairs contribute to the high activity of the solid FLPs for hydrogen dissociation and acetylene hydrogenation. 19 Besides oxide surfaces, 32−37 designing heterogeneous FLPs has been proved by various strategies and materials, 23,38 such as functionalizing metal− organic framework (MOF), 20,39,40 adsorbing molecules on solid surfaces 41−43 and doping two-dimensional materials. 44 Despite these significant advances in designing heterogeneous FLPs, metal elements are still indispensable for the construction of heterogeneous FLPs, which deviates from the initial metal-free concept of FLP catalysis.…”