Diploma Thesis Defense by Mr. Alexandros Tzitzouras
Thesis Title: «Study of dry reforming of methane on Ru-Ni bimetallic catalysts»
Friday 20 February 2020, at: 12:00, Venue: Hall Κ3.Α17
Examination Committee
- Professor Ioannis V. Yentekakis (advisor)
- Assistant Professor Nikolaos Xekoukoulotakis
- Assistant Professor Paraskevi Panagiotopoulou
Abstract
The subject of this thesis is the catalytic behavior of the nickel- (Ni) and ruthenium-nickel bimetallic (Ni − Ru) catalysts, as well as the effect of the supported carriers of Alumina, Alumina-Syria-Zirconia, Syrian-Zirconia during the dry biogas reforming (DRM) process. The process of dry biogas reforming involves the reaction of methane (CH4) and carbon dioxide (CO2) and the production of hydrogen (H2) and carbon monoxide (CO) products. This process has gained enormous environmental and industrial advantage, as this process exploits the two gaseous pollutants, in particular CO2 and CH4, which are considered important in their contribution to the greenhouse effect. In addition, the two gases produced are the main constituents of biogas and natural gas and are relatively inexpensive raw materials for the production of syngas, namely synthesis gas (H2 / CO) and its subsequent use as a fuel, which is particularly important if one considers H2 is considered the fuel of the future for electricity generation.
For the experimental procedure for the reaction study, the composition of the reactants selected is equimolar ([CO2] / [CH4] = 1/1). As for the active metal content of the catalysts, for the Ni − Ru bimetallic catalyst the content is 1% w.t Ru − 10% w.t Ni, whereas for the Ni mono catalyst it is 10% w.t Ni. These catalysts are supported on three different carriers. In addition to the commonly used alumina (γ − Al2O3), mixed oxide carriers and more specifically cerium (CeO2) and zirconium (ZrO2) - (CZ) carriers and the combination of the two with alumina (ACZ) will be studied. In general, the role of the carriers is quite important in enhancing catalytic activity and in limiting carbon deposition, and especially in the processes of dry methane reforming. From the results obtained, both the nickel (Ni) and the bimetallic nickel-ruthenium (Ni − Ru) catalysts examined did not appear to exhibit a tendency for carbon deposition on their surface, which is the main reason for their inactivation in hydrocarbon reforming. Of particular interest is the catalysts’ stability under the applied oxidative-reductive conditions. Also with regard to their performance at high temperatures, Ni and Ni − Ru catalysts based on the alumina carrier (γ − Al2O3) have been shown to be more active.
