Editors: | Vayenas Intl. Symp. / Physical Chemistry and its applications for sustainable development Edited by: F. Kongoli, E. Aifantis, C. Cavalca, A. de Lucas Consuegra, A. Efstathiou, M. Fardis, D. Grigoriou, A. Lemonidou, S.G. Neophytides, Y. Roman, M. Stoukides, M. Sullivan, P. Vernoux, X. Verykios, I. Yentekakis |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2019 |
Pages: | 249 pages |
ISBN: | 978-1-989820-09-4 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Global warming triggered by growing of the greenhouse gases concentration in the atmosphere actually represents the biggest world ecology problem. Carbon dioxide is one of the most important greenhouse gases because it is the main reason for global warming [1] Therefore, effective solutions to the global warming problem should be connected with the lowering of the carbon dioxide concentration in the atmosphere. One of the feasible protocols is to employ carbon dioxide as starting material and to convert it to the valuable compounds in various industrial processes which are very important. [2] For this purpose, iron-based materials act as a one of the most effective catalytic materials for carbon dioxide hydrogenation to methane, methanol and other simple important hydrocarbons. [3] Heterogeneous catalysis is connected with the active surface of catalysts. Therefore, the subject of the presented study is to investigate the influence of the catalyst’s physical state on its activity in hydrogenation of CO2.
Four types of iron oxide catalysts were prepared by high temperature decomposition of Iron (II) oxalate in the air. Afterword, its catalytic performance was studied at low pressure (1 bar) and low temperature (325°C) in the microreactor, Microactivity Effi, connected with a gas chromatograph for the detection of the reaction products. Depending on the order and rate of reaction, components mixing four different samples of the nanostructured iron oxide catalyst were prepared. After high temperature decomposition the composition of the prepared catalyst was determined by XRD and only hematite and magnetite in a various ratio between 90:10 down to 40:60 (hematite: magnetite) was observed in the emerging catalysts. Bigger differences between these catalysts were observed during reduction of the iron oxide in the hydrogen atmosphere by the XRD technique. Part of the samples produced zero valent iron but the second parts of the samples were reduced only to the form of pure magnetite. Also, observed catalytic activity of the prepared catalysts was different. The highest reaction rate, but also the lowest stability, was observed for catalysts which were reduced in the hydrogen atmosphere to zero valent irons, whereas catalysts which were reduced only to magnetite were substantially stable in selectivity of the production of methane in comparison with carbon monooxide. Unfortunately, total reaction rate was, in this case, slower. On the other hand, microstructured commercial Iron(II) oxide used as reference did not produce hydrocarbons (mainly methane), only carbon monoxide was observed as a carbon based product with this catalyst.