TY - THES

T1 - Structural Characterization of Carbons Derived from Methane Pyrolysis

AU - Knabl, Florian

N1 - embargoed until null

PY - 2021

Y1 - 2021

N2 - The world is currently facing the enormous task of massively reducing the carbon dioxide emissions for energy production within the next decades. Switching to hydrogen as an energy carrier is a possible approach for a sustainable and climate-neutral energy production. Hydrogen may be produced without carbon dioxide emissions by means of methane pyrolysis which yields large quantities of carbon as a complementary product. To allow a large-scale application of methane pyrolysis, this carbon must be put to use. In this thesis, carbons derived from three different laboratory-scaled methane pyrolysis processes were investigated using advanced characterization techniques including X-ray diffraction, small-angle X-ray scattering, gas sorption analysis, thermogravimetric analysis, and Raman spectroscopy. The carbon phase derived from a liquid metal process utilizing a catalyst of Cu and Ni was reported to be turbostratic carbon. The plasma process yielded a mixture of graphite and turbostratic carbon with a BET area of up to 75.8 m²/g. Graphite was reported from a fixed bed process using reduced iron ore as a catalyst. Contrary to multiple literature studies no other allotropic forms of carbons were detected, such as graphene, carbon nanotubes or carbon fibers. All carbons contained significant amounts of impurities in a range between 31.4 wt% and 89.7 wt%. Carbon purity must be increased in future studies for the carbon product to be marketable. Many potential high-tech applications of carbon require a nanoporous structure combined with a large specific surface area. This may be achieved in a subsequent activation step and should be investigated in future research.

AB - The world is currently facing the enormous task of massively reducing the carbon dioxide emissions for energy production within the next decades. Switching to hydrogen as an energy carrier is a possible approach for a sustainable and climate-neutral energy production. Hydrogen may be produced without carbon dioxide emissions by means of methane pyrolysis which yields large quantities of carbon as a complementary product. To allow a large-scale application of methane pyrolysis, this carbon must be put to use. In this thesis, carbons derived from three different laboratory-scaled methane pyrolysis processes were investigated using advanced characterization techniques including X-ray diffraction, small-angle X-ray scattering, gas sorption analysis, thermogravimetric analysis, and Raman spectroscopy. The carbon phase derived from a liquid metal process utilizing a catalyst of Cu and Ni was reported to be turbostratic carbon. The plasma process yielded a mixture of graphite and turbostratic carbon with a BET area of up to 75.8 m²/g. Graphite was reported from a fixed bed process using reduced iron ore as a catalyst. Contrary to multiple literature studies no other allotropic forms of carbons were detected, such as graphene, carbon nanotubes or carbon fibers. All carbons contained significant amounts of impurities in a range between 31.4 wt% and 89.7 wt%. Carbon purity must be increased in future studies for the carbon product to be marketable. Many potential high-tech applications of carbon require a nanoporous structure combined with a large specific surface area. This may be achieved in a subsequent activation step and should be investigated in future research.

KW - methane pyrolysis

KW - thermal decomposition of methane

KW - carbon characterization

KW - metal bath

KW - plasma

KW - fixed bed

KW - Methanpyrolyse

KW - Thermische Zersetzung von Methan

KW - Kohlenstoff-Charakterisierung

KW - Metallbad

KW - Plasma

KW - Festbett

M3 - Master's Thesis

ER -