Resolving the Reaction Mechanism for Oxidative Hydration of Ethylene toward Ethylene Glycol by Titanosilicate Catalysts

Abstract

Due to the complex internal structure of titanium silicalite-1, the reaction mechanism for oxidative hydration of ethylene toward ethylene glycol on the titanium silicalite-1 (TS-1) catalyst is still disputable and inconclusive. In this work, density functional theory calculations, microkinetic modeling, and experiments are combined to provide unique insights into the reaction mechanism. With consideration of perfect titanium sites (including isolated and dinuclear titanium sites) and hydrolyzed titanium sites, the results demonstrate that oxidative hydration of ethylene prefers a catalysis mechanism completed by the coupling of two types of active centers, where the isolated titanium site participates in ethylene epoxidation and the hydrolyzed titanium site is responsible for the hydration of ethylene oxide. The ethylene glycol generation rate, reaction order, and apparent activation energy calculated by microkinetic modeling are highly consistent with our experimental kinetics. This study provides a decisive description of the reaction mechanism for oxidative hydration of ethylene over TS-1 catalysts, which may enable further optimization of TS-1 by targeted modification on specific active centers.

Constructing a Highly Active Pd Atomically Dispersed Catalyst for Cinnamaldehyde Hydrogenation: Synergistic Catalysis between Pd–N3 Single Atoms and Fully Exposed Pd Clusters

“…We observe that the corresponding energy curve on Pd SA+C /g-C 3 N 4 is downhill and releases the most energy. This indicates that the Pd SA+C /g-C 3 N 4 catalyst is more favorable for the hydrogenation of the CC bond in CAL. , …”

“…This indicates that the Pd SA+C /g-C 3 N 4 catalyst is more favorable for the hydrogenation of the C�C bond in CAL. 45,46 As shown in Figures 6c,d, and S17, another important step in DFT research is the adsorption and dissociation of H 2 . Interestingly, H 2 gas is adsorbed on the Pd single atom and dissociated into two hydrogen atoms in a heterogeneous path.…”

Boosting Selective Oxidation of Ethylene to Ethylene Glycol Assisted by In situ Generated H2O2 from O2 Electroreduction

“…That is in situ generated * OOH on mesoporous carbon could directly transfer to the TS-1 catalyst, subsequently oxidize ethylene into ethylene glycol. This reaction process omits H 2 O 2 absorbing and dissociating over the TS-1 (uphill free energy change), [30] and lower the activation energy comparing to that using commercial H 2 O 2 as oxidant.…”

Boosting Selective Oxidation of Ethylene to Ethylene Glycol Assisted by In situ Generated H2O2 from O2 Electroreduction

“…Analogically, in our MC-3 and TS-1 electro-synthesizing EG system, the TS-1 catalyst could act as * OOH trapping agent due to the strong combination between them. [30] The in situ generated * OOH on mesoporous carbon could directly transfer to the TS-1 catalyst, forming the key active species Ti-OOH.…”