Formation of Acetylene in the Reaction of Methane with Iron Carbide Cluster Anions FeC₃⁻ under High‐Temperature Conditions

Abstract

The underlying mechanism for non‐oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C−C bond. For the first time, the elementary reaction of methane with atomic clusters (FeC3−) under high‐temperature conditions to produce C−C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well‐rationalized by quantum chemistry calculations. This study narrows the gap between gas‐phase and condensed‐phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non‐oxidative methane aromatization.

The Reactive Sites of Methane Activation: A Comparison of IrC3+ with PtC3+

“…Metal carbides are a kind of molecules with the potential to activate methane and have been studied by several groups [ 5 ]. Research on the mechanisms of the activation of methane by metal carbides is of great value and it may be helpful to find new catalysts of metal carbides [ 6 , 7 ]. At the same time, it is very difficult to study the activation mechanisms of methane.…”

“…At present, researchers are concerned about the reactions of methane with metal ions such as Os + [ 11 ], Pt + [ 12 ], Ta + [ 13 ] and Rh(0) [ 14 ] and metal oxides such as MgO + [ 15 ], PbO + [ 16 ], V 4 O 10 + [ 17 ] and Re 2 O 7 + [ 18 ]. In addition to metal ions and their oxides, studies have shown that metal carbides can also activate methane, such as FeC 6 − [ 19 ], Mo 2 C 2 − [ 20 ], Ta 2 C 4 − [ 21 ], FeC 3 − [ 6 ], AuC + [ 22 ], FeC 4 + [ 23 ] and M C + [ 7 ]. These studies have explored some possible mechanisms for the activation of methane by metal carbide clusters.…”

“…These studies have explored some possible mechanisms for the activation of methane by metal carbide clusters. For example, the study of AuC + reveals a special hydride-transfer mechanism (HT) [ 22 ], while the study of FeC 3 - shows that methane and atomic clusters generate CC-coupling reaction products at high temperatures and explained the possible mechanism of non-oxidized methane aromatization at the molecular level [ 6 ]. The study of FeC 4 + shows that the cluster can activate the C–H bonds of methane via the hydrogen-atom transfer (HAT) mechanism at ambient temperature; the study used the frontier orbital theory to explain the root cause of the HAT reaction [ 23 ].…”

Towards C1 chemistry: methanol vinylation by CaC2 in water in the presence of potassium or sodium carbonates

“…One of the methanol‐based prospective monomers and chemicals is known to be methyl vinyl ether (MVE), mainly manufactured by vinylation of methanol with acetylene . The latter is also an industrially multi‐thousand ton raw material, produced both from methane, coal and biomass (via calcium carbide, CaC 2 ) . Furthermore, CaC 2 is now rated as a renewable source for a number of commodity chemicals.…”

Unraveling the Activity of Iron Carbide Clusters Embedded in Silica for Thermocatalytic Conversion of Methane

“…Recently, a combined experimental and computational study, 26 in which reactivity of various iron-carbide cluster anions (FeC − y ) towards methane was investigated in high temperature conditions (300K-700K), has revealed that FeC − 3 cluster is much more active than FeC − 2 . Based on these works, it is of interest to investigate stability as well as catalytic activity of different iron-carbide clusters embedded in SiO 2 framework.…”