TY - THES ID - 147678930 TI - Use of anion exchange membranes for hydrogen production from sunlight and air AU - Segers, Alexandre AU - Rongé, Jan AU - Martens, Johan AU - KU Leuven. Faculteit Ingenieurswetenschappen. Opleiding Master of Chemical Engineering (Leuven) PY - 2019 PB - Leuven KU Leuven. Faculteit Ingenieurswetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:147678930 AB - Global climate change is a huge struggle for mankind. Just as the search for new renewable energies, also new methods to store these energies are needed. Water electrolysis to produce hydrogen is a very attractive method to achieve this storage, although costs are high compared with hydrogen from fossil fuels. To increase efficiency and reduce costs, hydrogen could be produced from water vapor instead which would resolve the need of pure water and water transport auxiliaries. To electrically separate anode and cathode electrodes, transport anions and separate product gasses in this type of electrolysis device, an anion exchange membrane is used. In this Master's thesis, a detailed study was made of the effect of crosslinking with glutaraldehyde on a KOH-doped poly(vinyl alcohol) membrane. First, the method to obtain crosslinking was investigated. It was found that acidic conditions were required to obtain crosslinking with glutaraldehyde. It seemed that no crosslinking occurred when alkaline conditions were used or only moderate acidic conditions. This was confirmed with KOH uptake and water uptake in humid nitrogen gas that both decreased with increasing glutaraldehyde content when acidic conditions were used for crosslinking, presumably due to increased hydrophobicity caused by crosslinking. Only high degrees of crosslinking seemed to prevent leaching of KOH when immersed in liquid water. In-plane conductivity measurements of membranes should be performed with care because it appeared that the leaching out of KOH on the surface between the electrodes can give unreliable results. Also, it seems that electrons do not use the whole membrane for transport, meaning that they do not instantly spread over the whole cross section. This leads to a calculated conductivity which is too low. For small segments this problem is more significant as the electrons have a smaller length to spread over the cross section of the membrane. Therefore, conductivity data from literature could be questioned as these interferences could also have occurred. When using a crosslinked KOH-doped poly(vinyl alcohol) gel for hydrogen production of water vapor, a performance increase of up to 70\% over 12 hours was achieved compared to a non-crosslinked membrane. These promising results indicate that crosslinked gels could be used for vapor-fed water electrolysis, although long term stability of the performance should still be investigated in future research. ER -