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Kemian tekniikan korkeakoulu | Master's thesis
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Process Systems Engineering
Master's Programme in Chemical Technology
AbstractThis thesis presents an investigation into the preparation of carbon–based catalyst produced from biochar formed via intermediate pyrolysis and post–reforming during the thermo–catalytic reforming (TCR®) process. The report is split into two sections; part one is a literature survey that details the preparation and characterisation methods for carbon–based catalysts as well as the possible industrial applications for the catalysts. The second part is the experimental section, presenting the materials and methodologies as well as the results and discussions. Initially, eight biochars were characterised using various techniques and out of them, three biochars i.e. olive stone, digestate and corn stover were selected for the preparation of the carbon–based catalysts. Digestate derived biochar showed highest BET specific surface area of 104.31 m2g–1 with the lowest pore size and total pore volume of 0.14 µm and 0.81 cm3g–1. The corn stover derived biochar showed the lowest BET specific surface area of 1.06 m2g–1, whereas olives stones derived biochar showed BET specific surface area of 46.42 m2g–1. The Van Krevelen plot depicted that the digestate derived biochar had the highest aromatic characteristic compare to all the biochars, which was then followed by olive stones and later comes corn stover derived biochars. All three selected biochars showed good thermal stability under inert and atmospheric conditions. Furthermore, several mineral components were detected and measured in the biochars by ICP–MS analysis and the presence of these elemental components was also complemented through x–ray diffraction analysis. The x–ray diffractograms displayed the amorphous phase and mineral crystals present in the biochars. Carbon–based catalysts were prepared by applying a chemical activation process, using potassium hydroxide (KOH) as activating agent. The characterisation of activated carbon catalyst showed that olives stones derived activated carbon catalyst experienced the highest growth in the BET specific surface area of 121.17 m2g–1; whereas corn stover derived biochar developed the lowest BET specific surface area of 14.56 m2g–1. The digestate derived activated carbon catalyst had the largest BET specific surface area of 146.64 m2g–1. Thermal stability of the activated carbon catalyst was found to be reduced as compared to their precursors. X–ray diffractogram depicted an increase in the amorphous characteristics of activated carbon catalyst. To conclude, this study revealed that the biochars from TCR® process have emerged as a promising material especially due to high carbon content and have potential to reduce the dependency on the conventional catalyst materials.
Thesis advisorApfelbacher, Andreas
activated carbon, biochar, carbon-based materials, characterisation, KOH chemical activation method, impregnation method