DFT Mechanistic Study on the Complete Oxidation of Ethylene by the Silica-Supported Pt Catalyst: C═C Activation via the Ethylene Dioxide Intermediate

Abstract

Low-temperature complete oxidation of ethylene by the mesoporous silica-supported Pt catalyst is a forefront technology for food preservation. Public implementations of the Pt catalyst have already begun, and spectroscopy analyses on the catalytic mechanism have been reported. In this study, density functional theory calculations were conducted to clarify the potential energy profile and electronic mechanism of the catalytic reaction. Based on the experimental findings, a reaction pathway was proposed for ethylene oxidation up to CO2 formation via the HCHO intermediate. Among several possibilities, a reaction pathway via ethylene dioxide species is energetically plausible for the C–C bond cleavage to generate HCHO. Particular focus was given to the electronic effect of the silica support in the ethylene dioxide route. The reservoir effect, in which the siloxide groups take electrons from the Pt moiety, reduces the activation energy of the C–C bond cleavage step by taking electrons from the σ­(C–C) orbital.

Hierarchical Porous Wood Cellulose Scaffold with Atomically Dispersed Pt Catalysts for Low-Temperature Ethylene Decomposition

“…The ethylene molecules are sequentially oxygenized to the dioxide intermediately, which undergoes C–C σ-bond cleavage to form HCHO. The edge-effect and the surface-active oxygen species , on catalyst have significant influences on the C–C σ-bond cleavage by reducing the activation energy. The HCHO is further oxidized to CO and then to CO 2 , whereas H atoms generated from HCHO will react with O atoms to form H 2 O molecules, but part of HCHO can be oxidized into HCOOH as a form of formic acid and formate species .…”

“…The HCHO is further oxidized to CO and then to CO 2 , whereas H atoms generated from HCHO will react with O atoms to form H 2 O molecules, but part of HCHO can be oxidized into HCOOH as a form of formic acid and formate species . Miyazaki’s study indicates that the CO oxidation step is the rate-determining step in the complete ethylene oxidation . The H 2 O molecules adsorbing onto the active sites is the main reason for the deactivation …”

“…The ethylene molecules are sequentially oxygenized to the dioxide intermediately, which undergoes C−C σ-bond cleavage to form HCHO. The edge-effect 41 and the surfaceactive oxygen species 10,42 on catalyst have significant influences a Including the coordination number N, the interatomic distance R between the absorber and backscatter atom, the mean-square disorder in the distance σ 2 , and the energy correction term ΔE. A fixed amplitude factor S 0 2 of unity was used for the fitting.…”

“…11 Miyazaki's study indicates that the CO oxidation step is the ratedetermining step in the complete ethylene oxidation. 41 The H 2 O molecules adsorbing onto the active sites is the main reason for the deactivation. 43 A more practical study of the catalytic performance of WTi and WTi-Pt2.5 was carried out in a continuous reactor with trace ethylene (80 ppm) at 25 and 0 °C, respectively.…”

Theoretical Study of the Propene Combustion Catalysis of Chromite Spinels: Reaction Mechanism and Relation between the Activity and Electronic Structure of Spinels

“…In this regard, we need correct knowledge of reaction mechanisms including the C–C single and CC double bond cleavages, rate-determining step, activation energy, and determination factor(s) for catalytic activity in the complete combustion of the light alkenes and alkanes. However, such knowledge has currently not been presented yet except for a few pioneering works. − …”