Thesis Title: CO₂ hydrogenation for methane production on supported Rh-nanoparticles. Effect of the support

Friday 12 July 2019, at: 12:00, Venue: Hall Κ2.A3

Examination Committee

• Professor Ioannis Yentekakis (advisor)
• Professor Evangelos Gidarakos
• Dr. Grammatiki Goula

Abstract

In our times the majority of our energy needs is being covered by the burning of fossil fuels, which leads to increased levels of carbon dioxide CO₂ in emissions. The increase of CO₂ concentrations in the atmosphere, as a result of the uncontrolled usage rate of fossil fuels, is one of the main reasons that cause the enhancing of the Greenhouse Effect leading to global climate changes. There is an urgent need for the development of technologies that will replace the use of fossil fuels and reduce the accumulation of CO₂ in the atmosphere. A very promising solution, which covers both needs, is the CO₂ hydrogenation reaction, a process that produces environmental friendly fuels of high energy content such as methane, carbon monoxide and methanol.

The aim of this thesis is to study the catalytic efficiency of three rhodium Rh catalysts, each of which is supported on a different support, in the hydrogenation of CO₂ reaction for the production of methane CH₄. During the experimental procedure we prepared, characterized and tested the following catalysts: 1%Rh/Al₂O₃, 1%Rh/50%CeO₂ 50%ZrO₂ and 1%Rh/80%Al₂O₃ 10%CeO₂ 10%ZrO₂.

The preparation of the catalysts was followed by the experimental procedure of BET for the specific surface area analysis of each of the catalysts. Then, the catalytic performance at the CO₂ hydrogenation reaction for the production of methane (methanation) of these catalysts was studied by a catalytic activity experimental procedure. An amount of 50mg of the catalyst was loaded in a fixed bed reactor fed with a constant 100 cm³/min flow of a gas mixture composed of 20% H₂, 5% CO₂ and 75% Ar under 1 atm pressure. The reactor was gradually heated up to 600^oC, while every 30^oC the reaction products were being analyzed with on-line gas chromatography.

The  1%Rh/80%Al₂O₃ 10%CeO₂ 10%ZrO₂ catalyst had the best catalytic performance at the CO₂ hydrogenation reaction while the 1%Rh/Al₂O₃ catalyst had a very similar performance. On the contrary the 1%Rh/80%Al₂O₃ 10%CeO₂ 10%ZrO₂ had a significantly lower performance.