PhD Thesis Defence Presentations - Christos Chatzilias

Presentation Title (Τίτλος Παρουσίασης): Study of the Electrochemical Promotion of CO2 hydrogenation in fuel cells and semi-pilot reactors
Presentation Type (Τύπος Παρουσίασης): PhD Thesis Defence Presentations
Speakers Full Name (Ονοματεπώνυμο): Christos Chatzilias
Speakers Affiliation (Προέλευση Ομιλητή): Department of Chemical Engineering, University of Patras
Seminar Room (Αίθουσα): "A. C. Payatakes" Library
Event Date: Tue, Sep 27 2022, Time: 11:00 - 14:00
Live webConference Link: https://upatras-gr.zoom.us/j/93708564344?pwd=eFRjc1VFRVFQQ2w4cVgwNTZpZWxsdz09
Abstract (Περίληψη)

The effect of the Electrochemical Promotion of Catalysis (EPOC) or non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA effect) acsts as a bridge between the fields of Electrochemistry and Catalysis. The phenomenon of EPOC aims to increase the catalytic rate and/or the selectivity of a given reaction. From the early 1980s to the present this phenomenon has been investigated and established through its successful application on a variety of catalytic reactions using a wide range of metal catalysts, such as Pt, Pd, Rh, Ag, Ni, Co, Au, Fe, IrO2, RuO2 deposited on various solid electrolytes, such as O2-, H+, Na+, K+ ion conductors. In addition, EPOC has been successfully applied to catalytic systems using aqueous electrolytes, mixed ionic-electronic conductors, as well as in molten salt electrolytes. A plethora of physicochemical and electrochemical methods were employed to interpret the phenomenon, investigate its principles, and explain its mechanism. It was shown that the phenomenon is closely related to the modification of the work function of a metal catalyst, due to the electrochemical migration of ions/promoters from the solid electrolyte to the metal/gas interface, where an effective double layer is formed.

The aim of this PhD thesis is to investigate the EPOC phenomenon for the hydrogenation of CO2, a reaction of major environmental importance, under two distinct catalytic systems, which are both based on Ru catalytic films deposited on YSZ solid electrolytes (i.e., O2- ion conductors). More specifically, EPOC was successfully applied both to a semi-pilot scale Monolithic Electrochemically Promoted Reactor (MEPR) as well as to a Solid Oxide Fuel Cell (SOFC) reactor.

The First Chapter of the dissertation discusses the importance of managing CO2, which is one of the main gasses responsible for the greenhouse effect. The production of useful compounds and chemicals via the hydrogenation of CO2 is also discussed. The Reverse Water Gas Shift (RWGS) and methanation (Sabatier) reactions are presented since they were both observed in the present investigation.

An important review of electrochemical cells, mainly fuel cells, and the thermodynamic properties governing their operation, as well as the various O2- electrolytes involved in this research, is provided. Furthermore, a major part of this chapter is dedicated to the description of EPOC phenomenon, its history, mechanism, the rules that govern it, and its quantification. The chapter ends with a revision of previous EPOC studies on the CO2 hydrogenation reaction that can be found in literature.

In the Third Chapter, the experimental apparatus, as well as the procedure followed for the structure and operation of the reactors and electrode preparation are described in detail. In addition, the same chapter, discusses thoroughly the characterization techniques which have been utilized to obtain information on the structure and physicochemical properties of the electrodes.

The Fourth Chapter deals with the study of EPOC for the CO2 hydrogenation reaction on Ru catalytic films deposited on YSZ solid electrolyte plates utilizing the MEPR. The investigation was carried out in the temperature range between    220 oC and 370oC under high volumetric flowrates (up to 2500 cm3/min) of reactant mixtures, ambient pressure, and three different reactants partial pressures ratios (PCO2:PH2= 1:7, 1:2 and 2:1), corresponding to reducing, slightly oxidizing (for the methanation reaction) and oxidizing conditions, respectively, based on the stoichiometry of the two reactions taking place (Sabatier and RWGS). In addition, information obtained via the physicochemical characterization techniques, namely Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD), are also discussed.

The kinetic mechanism of EPOC for the CO2 hydrogenation reaction using the MEPR semi-pilot configurations is analyzed in the Fifth Chaper. The study was carried out under atmospheric pressure, at 370 oC, with a flowrate of 1000 cm3/min and over a wide range of reactant partial pressures. The agreement between the results and the predicted behavior from the EPOC rules is also presented. Furthermore, the catalyst surface morphological and electronic characteristics, before and after the reactions, using X-ray Photoelectron Spectroscopy (XPS) technique are described in datail in the same chapter.

The Sixth Chapter, which is the last one, presents the results of EPOC effect on the CO2 hydrogenation reaction utilizing the power of a low temperature SOFC (i.e., self-promoted reactor). The study was carried out within a temperature range of 200 to 460 oC. Fuel cell performance was investigated under both the absence of CO2 (i.e., only hydrogen at the anode compartment) and the presence of both reactants (dual operation, as a fuel cell as well as a catalytic reactor). Furthermore, the physicochemical characterization of the electrodes before and after the experiments is also presented.

Speakers Short CV (Σύντομο Βιογραφικό Ομιλητή)

EDUCATION

Α. PhD Candidate

10/2018 - 09/2022

Laboratory of Chemical & Electrochemical Processes, Department of Chemical Engineering, University of Patras

PhD thesis title:

''Study of the Electrochemical Promotion of CO2 hydrogenation in fuel cells and semi-pilot reactors''.

Advisor:

Professor Alexandros Katsaounis

Β. Diploma in Chemical Engineering

10/2012 - 03/2018

Department of Chemical Engineering, University of Patras

Diploma degree: 7.8/10

Diploma thesis title:

"Comparison of theoretical predictions and actual electricity production from photovoltaic panels (based at Chemical Engineering Dpt. of University of Patras)"

Advisor:

Associate Prof. Eleftherios Amanatides

PUBLICATIONS IN PEER-REVIEWED JOURNALS

  1. C. Chatzilias, E. Martino, D. Zagoraios, G. Kyriakou and A. Katsaounis, Electrochemical Promotion of Catalysis for CO2 valorisation. Springer Nature. 2022 (book chapter, in press)
  2. C. Chatzilias, E. Martino, C. G. Vayenas, G. Kyriakou, A. Katsaounis (2022) A low temperature SOFC as self-promoted reactor for CO2 catalytic hydrogenation. Appl Catal B Environ 317:121778. doi: 10.1016/j.apcatb.2022.121778
  3. C. Chatzilias, E. Martino, S. Tsatsos, G. Kyriakou, A. Katsaounis, C. G. Vayenas (2022) Kinetic study of CO2 hydrogenation on Ru/YSZ catalyst using a monolithic electropromoted reactor (MEPR). Chem Eng J 430. doi: 10.1016/j.cej.2021.132967
  4. C. Chatzilias, E. Martino, A. Katsaounis, C. G. Vayenas (2021) Electrochemical promotion of CO2 hydrogenation in a monolithic electrochemically promoted reactor (MEPR). Appl Catal B Environ 284:119695. doi: 10.1016/j.apcatb.2020.119695

PARTICIPATION IN CONFERENCES

  1. A. Lymperi, C. Chatzilias, E. Martino, C. G. Vayenas, G. Kyriakou, A. Katsaounis, "Wireless Electrochemical Promotion of catalytic reactions using low temperature SOFCs. The case of CO2 hydrogenation". 13th Hellenic Conference of Chemical Engineering, Patras, June 2-4, 2022 (speech)
  2. D. Kinderlis, C. Chatzilias, E. Martino, C. G. Vayenas, G., A. Katsaounis, "Electrochemical promotion of CO2 hydrogenation reaction over Pt catalytic films to CO production". 13th Hellenic Conference of Chemical Engineering, Patras, June 2-4, 2022 (poster)
  3. C. Chatzilias, E. Martino, D. Grigoriou, D. Zagoraios, A. Katsaounis and C. G. Vayenas, "Electrochemical Promotion of CO2 Hydrogenation on thin porous Ruthenium catalytic films deposited on YSZ in single pellet and monolithic reactors", 17th International Congress on Catalysis (ICC2020), San Diego, California, USA, June 14-19, 2020, (speech).
  4. C. Chatzilias, E. Martino, D. Grigoriou, D. Zagoraios, A. Katsaounis and C. G. Vayenas, "Electrochemical promotion of CO2 hydrogenation on thin porous ruthenium catalytic films deposited on YSZ in single pellet and monolithic reactors", 5th Workshop of Graduates & Post-Docs in Chemical Engineering Sciences, Patras, November 06, 2019, (poster)
  5. D. Zagoraios, C. Chatzilias, A. Athanasiadi, I. Kalaitzidou, S. Ntais, A. Katsaounis, A. Caravaca, P. Vernoux, C. G. Vayenas, "Electrochemical promotion of methane oxidation over nanodispersed Pd/Co3O4 catalysts", 2019 Sustainable Industrial Processing Summit and Exhibition, Paphos, October 23-27, 2019 (speech)
  6. C. Chatzilias, D. Zagoraios, A. Katsaounis and C. G. Vayenas, "Supported and unsupported Pd nanoparticles as active catalysts for the electrochemical promotion of catalysis of the methane oxidation reaction", 12th Hellenic Conference of Chemical Engineering, Athens, May 29-31, 2019 (poster)

PARTICIPATION IN SCIENTIFIC PROJECTS

  1. 12/2018 - 02/2022                                                                                                                                                                                       Research scholarship, in the framework of the program "80464: Scale up of Electrochemically Promoted Catalytic Hydrogenation of CO2 for fuel production'', ACRONYM: CO2 TO FUELS, Project Code: Τ1ΕΔΚ-01631, EPAnΕΚ 2014 – 2020. Co‐financed by the European Union and Greek national funds.
  2. 05/2022 - 09/2022                                                                                                                                                                                   Research scholarship, in the framework of the program "80109: Revenue management for the development of the PP - Investigation of the carbon footprint of the University of Patras" financed by the University of Patras with Scientific Manager Mr. Ch. Bouras.