TY - THES

T1 - The potential of biomass-derived activated carbons for hydrogen storage

AU - Stock, Sebastian

N1 - embargoed until null

PY - 2021

Y1 - 2021

N2 - Habits are fundamental parts in every human’s life and some of them need to change to make a step forward in slowing down global warming. As oddly as it may sound, the most common habit of enjoying a freshly brewed cup of coffee every morning may contribute to a certain extend to this deceleration. The spent coffee grounds, upon chemical treatment, can be used to store the fuel which can power the cars of the future, namely hydrogen. Storing hydrogen in activated carbons synthesized from biological waste materials contributes to the solution of the problem in two ways. Firstly, for the transition to a carbon free society the need for electrified vehicles is increasing, which battery-containing cars cannot stem alone. Therefore, hydrogen powered cars, using a fuel cell to generate electricity, are a promising addition to this sector. Those fuel cells need gaseous hydrogen, which can be stored in activated carbons derived from coffee waste. Secondly, the waste can be brought back to new use, thus increasing the sustainability of such a storage system even more. The structural characteristics of three biomass-derived activated carbons, namely spent coffee grounds, silver skin from coffee beans and fines from paper production, were investigated in this thesis. This was accomplished using Raman spectroscopy, X-ray scattering and gas sorption analysis with different gases. To evaluate the hydrogen storage capacity, low-pressure (0-1 bar) hydrogen adsorption/desorption experiments were conducted at three different temperatures (77, 87 and 97 K). It was found that the pore width, the specific surface area, and the pore volume play an important role in the hydrogen uptake performance. With decreasing mean pore width, the hydrogen uptake at 1 bar and 77 K was found to increase. The sample derived from spent coffee grounds has the highest uptake of 2.81 wt%, followed by the coffee silver skins with 2.77 wt% and 1.47 wt% for the sample synthesized from fines. The first two materials, due to their relatively high uptake at low pressures, have a great potential for an application in hydrogen storage systems operating in cryogenic conditions.

AB - Habits are fundamental parts in every human’s life and some of them need to change to make a step forward in slowing down global warming. As oddly as it may sound, the most common habit of enjoying a freshly brewed cup of coffee every morning may contribute to a certain extend to this deceleration. The spent coffee grounds, upon chemical treatment, can be used to store the fuel which can power the cars of the future, namely hydrogen. Storing hydrogen in activated carbons synthesized from biological waste materials contributes to the solution of the problem in two ways. Firstly, for the transition to a carbon free society the need for electrified vehicles is increasing, which battery-containing cars cannot stem alone. Therefore, hydrogen powered cars, using a fuel cell to generate electricity, are a promising addition to this sector. Those fuel cells need gaseous hydrogen, which can be stored in activated carbons derived from coffee waste. Secondly, the waste can be brought back to new use, thus increasing the sustainability of such a storage system even more. The structural characteristics of three biomass-derived activated carbons, namely spent coffee grounds, silver skin from coffee beans and fines from paper production, were investigated in this thesis. This was accomplished using Raman spectroscopy, X-ray scattering and gas sorption analysis with different gases. To evaluate the hydrogen storage capacity, low-pressure (0-1 bar) hydrogen adsorption/desorption experiments were conducted at three different temperatures (77, 87 and 97 K). It was found that the pore width, the specific surface area, and the pore volume play an important role in the hydrogen uptake performance. With decreasing mean pore width, the hydrogen uptake at 1 bar and 77 K was found to increase. The sample derived from spent coffee grounds has the highest uptake of 2.81 wt%, followed by the coffee silver skins with 2.77 wt% and 1.47 wt% for the sample synthesized from fines. The first two materials, due to their relatively high uptake at low pressures, have a great potential for an application in hydrogen storage systems operating in cryogenic conditions.

KW - Wasserstoffspeicher

KW - nanoporöse aktivierte Kohlenstoffe

KW - Röntgenstreuung

KW - Ramanspektroskopie

KW - Gas Sorptionsanalyse

KW - hydrogen storage

KW - nanoporous activated carbon

KW - X-ray scattering

KW - Raman spectrocopy

KW - Gas sorption analysis

M3 - Master's Thesis

ER -