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Oxide-zeotype bifunctional catalysts efficient for the conversion of CO to light olefins

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Français - Anglais

Date Limite Candidature : mercredi 17 août 2022

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General information

Reference : UMR5256-STELOR-002
Date of publication : Wednesday, July 27, 2022
Scientific Responsible name : Stéphane Loridant
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 November 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Light olefins (C2-C4) are key intermediates in the chemical industry. They are produced by steam cracking or catalytic cracking, two very energy-intensive processes currently using fossil resources. More eco-efficient and dedicated production is a major challenge. In the future, it could be based on syngas from different resources (fossil, biomass, waste). Unlike the Fischer-Tropsch process, the Ox-Zeo process, which combines a hydrogenating oxide and an acidic zeotype, makes it possible to obtain high selectivities in light olefins with great stability. However, the CO2 selectivity must be reduced and the catalytic activity improved. Work in 2021 showed that mixtures of ZnZrCeOx and SAPO-34 or RUB-13 allow very high light olefin selectivities (>80%) and low CO2 selectivities (5%) to be obtained at 300°C and Patm. These new bifunctional catalysts are also efficient for the conversion of CO2 to light olefins and therefore deserve to be studied in more detail.
However, previous work has focused on the search for performance and it appears necessary to remove the scientific barriers by determining the role of oxygen vacancies, OH species (and associated frustrated pairs) and O species mobility, clarifying the role of each element (coordination, electronic state) and their interactions in mixed oxides such as ZnCeZrOx and determining the influence of acidity (nature, strength, density) on the reaction mechanisms within the SAPO-34 and RUB-13 zeotype and on the olefin/paraffin ratio.
The ANR OXZEO project, which aims to answer these questions, should shed new light on the knowledge of ZnCeZrOx oxides combined with either SAPO-34 or RUB-13 zeotypes to selectively and stably convert CO into light olefins and finally propose new formulations based on structure-property relationships.
For this purpose, a fundamental and interdisciplinary work is proposed for this thesis. It includes the synthesis and characterisation of ZnCeZrOx oxides and zeotypes SAPO-34, RUB-13 with well-defined and modulated properties, the measurement of the catalytic properties of oxide-zeotype mixtures for the conversion of CO to light olefins and advanced characterisation based on in situ/operando techniques, some of which have never been deployed.

Work Context

The thesis will be carried out at the Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELyon) which is a joint research unit under the supervision of the CNRS and the University of Lyon 1. Comprising about 100 staff from the CNRS and Higher Education and an equivalent number of student trainees, post-doctoral fellows, and visiting researchers, it is one of the largest catalysis research laboratories in France and Europe.
The thesis will be carried out in the CATREN team, which is dedicated to heterogeneous catalysis for the energy transition, and has 30 members: 8 researchers, 3 technical staff, 4 post-doctoral students, 6 PhD students and 6 trainees. Its research activities focus on three areas:
- Heterogeneous catalysis of C1 transformation, i.e. compounds comprising only one carbon atom (mainly methane, methanol, carbon dioxide and carbon monoxide)
- The conversion of energy into chemicals (power-to-chemicals)
- Conversion of bioresources and fossil resources

The work will be carried out in collaboration withIC2MP in the framework of the ANR OXZEO project. It will be supervised by Stéphane Loridant and Pavel Afanasiev at IRCELYON.

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