Project

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In situ investigation of ethylene epoxidation on silver supported nanoparticles: from catalytic process to chemical looping

Applicant Artiglia Luca
Number 196946
Funding scheme Project funding
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Inorganic Chemistry
Start/End 01.09.2021 - 31.08.2025
Approved amount 306'964.00
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All Disciplines (3)

Discipline
Inorganic Chemistry
Physical Chemistry
Material Sciences

Keywords (5)

Chemical looping; In situ X-ray photoelectron spectroscopy ; Ethylene epoxidation; Supported silver nanoparticles; Oxygen carriers

Lay Summary (Italian)

Lead
L’etilene, il più semplice alchene con formula C2H4, ha una produzione mondiale annua che supera quella di qualsiasi altro composto organico. Può essere ottenuto tramite steam cracking di idrocarburi o dall’etano, uno dei principali componenti del gas naturale. Viene prevalentemente utilizzato nella sintesi di ossido di etilene (EO), un importante intermedio di reazione nella produzione di plastiche, detergenti e prodotti farmaceutici. La produzione annua di EO aumenta mediamente del 2%. EO è ottenuto tramite ossidazione selettiva di etilene, e il processo viene catalizzato con buone rese su nanoparticelle di argento supportate su ossido di alluminio. Nonostante i numerosi studi volti alla caratterizzazione completa del sistema, molte domande riguardo al funzionamento del ciclo catalitico, al fine di ottimizzarlo, rimangono irrisolte.
Lay summary

Lo scopo principale del progetto è caratterizzare, tramite metodi spettroscopici avanzati sviluppati all’istituto Paul Scherrer, catalizzatori per l’epossidazione di etilene a base di nanoparticelle di argento supportate su ossido di alluminio. Tali metodi consentiranno l’identificazione delle specie attive formate all’interfaccia solido-gas e dell’intermedio di reazione che porta all’ottenimento del prodotto desiderato. Oltre a questo, verranno caratterizzati nuovi materiali che consentono un aumento della selettività della reazione tramite un processo di chemical looping. Tale approccio, basato sull’utilizzo di supporti aventi alta mobilità di ossigeno reticolare, è altamente innovativo e non sono ancora stati riportati studi a riguardo. L’obiettivo è di comprendere il meccanismo che porta all’aumento della selettività, e di fornire importanti spunti per lo sviluppo futuro di materiali sempre più efficienti.

Direct link to Lay Summary Last update: 29.10.2020

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Abstract

Ethylene epoxidation leads to the production of ethylene oxide, a commodity used to synthesize plastics, pharmaceuticals, detergents, etc. with a yearly increasing production. The industrial catalyst consists of promoted silver nanoparticles supported on alumina, and its catalytic performances have been thoroughly tested. Although several research efforts have been spent to spectroscopically characterize the system, many of them focused on model systems mimicking the actual catalyst, fundamental research questions remain. Recently, a new approach based on chemical looping has been proposed as an alternative to the catalytic reaction. By means of chemical looping, a process is split into multiple steps, within which a specific reaction intermediate forms and is stabilized. In the case of epoxidation, it avoids the dosing of a potentially explosive mixture of ethylene and oxygen, allows an easier separation of the ethylene oxide product, and enables to control the conditions of each of the reaction steps. Although some chemical looping tests have been carried out, the reaction mechanism and the relevant materials structures still need to be understood. Ambient pressure x-ray photoelectron spectroscopy and electron yield near edge x-ray absorption fine structure spectroscopy are suitable techniques to investigate in situ the solid-gas interface under relevant reaction conditions (gas environment and temperature). Combining such techniques with a complete pre-characterization and testing of the catalytic/chemical looping performances of powder samples and with theoretical calculations, the main goals of this project are:i) to investigate and characterize active sites involved in the catalytic reaction on actual samples;ii) to detect reaction intermediate/s formed during the catalytic reaction in the absence/presence of promoters on actual samples;iii) to investigate in situ the chemical looping epoxidation, characterizing the active sites, the role of the oxygen carrier supports and understanding the reaction mechanism, comparing it to the catalytic one.The project is ambitious and fills the pressure and material gaps that typically divide catalysis and surface science, to provide a complete understanding of a fundamental process. Theoretical calculations will help to combine the spectroscopic findings with the reactivity tests, so that the results will be of potential interest to develop new materials and to understand how chemical looping works and under what conditions it may be a valid alternative to the catalytic process.
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