Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, -, Turkey
Approval Date: 2020
Thesis Language: Turkish
Student: ÇİĞDEM OKUTAN
Co-Supervisor: NAİL YAŞYERLİ, HÜSEYİN ARBAĞ
Open Archive Collection: AVESIS Open Access Collection
Abstract:The aim of this study is to develop active, stable and carbon-resistant catalysts to produce synthesis gas by dry reforming of methane. For this purpose, SBA-15 supported Ni, Ni-Al, Ni-Zr, and Ni-Ti catalysts and Al-SBA-15, Zr-SBA-15 supported Ni catalysts were synthesized by different methods. Mesoporous SBA-15 support material was synthesized by using a hydrothermal procedure. Al-SBA-15 and Zr-SBA-15 support materials were synthesized following a one-pot hydrothermal synthesis method in three different synthesis conditions using HCl (A), NaCl (S) and both HCl and NaCl (B). All catalysts were characterized by XRD, N2 adsorption-desorption isotherms, ICP-OES, SEM, TEM, TG and pyridine adsorbed FTIR analysis before and/or after reaction tests. All prepared catalysts were tested in dry reforming of methane at 750 °C in a fixed bed reactor. Among SBA-15 supported Ni, Ni-Al, Ni-Zr, and Ni-Ti catalysts prepared by the impregnation method, 5Ni@ catalyst showed the highest catalytic activity in dry reforming of methane; however, a high amount of carbon formation was obtained in the structure of this catalyst. Although Al-SBA-15 supported Ni catalyst prepared by adding HCl and NaCl together to the synthesis solution showed high catalytic activity, there was also a high amount of carbon deposition in the structure of this catalyst. The highest catalytic activity achieved in this study (86% CH4 and 88% CO2 conversion, 1.36 H2 yield) was obtained in 5Ni@10Al (n)-B catalyst, which was synthesized using aluminium nitrate salt to investigate the effect of aluminium source on catalyst activity and carbon formation, and the amount of carbon on catalyst surface at the end of 4 h reaction was 0.015%. Among Zr-SBA-15 supported Ni catalysts, the highest catalytic activity was obtained with 5Ni@10Zr-A catalyst. It was found that the synthesis condition changed the structural and physical properties of the product, and in particular the morphology and acidity of the SBA-15 material. The apparent activation energy of the reaction was found to be 16.45 kcal/mol as a result of experimental studies conducted on 5Ni@10Al (n)-B catalyst.