Çeşitli çimento türleri üzerine yüklenmiş geçiş metal nanopartiküleri: Sodyum borhidrür metanolizinde katalizör ve inşaat alaninda yapi malzemesi olarak kullanimi

The increase in energy use, especially in parallel with the increase in urbanization, has directed researchers to clean energy sources from fossil fuels, which are at risk of extinction by the 2050s. This trend is particularly focused on clean, non-toxic and colorless hydrogen energy, which is attracting attention among renewable energy sources. However, it is essential to find a solution to the problem of transporting and storing hydrogen energy and important studies are still ongoing for this purpose. In this context, hydrogen is obtained from solid hydrogen storage materials such as metal hydrides (NaBH4, LiBH4, Mg(BH4)2 etc.) and amine-boranes (NH3BH3, Me2NHBH3, N2H4BH3) using catalytic methods. Among these, NaBH4 (sodium borohydride) has significant advantages due to its water solubility, hydrogen content (10.8% by weight), stability, durability and environmental friendliness. However, it is necessary to design a catalyst that will produce hydrogen gas from NaBH4 by appropriate techniques (dehydrogenation, thermolysis and solvolysis etc.). In this thesis, the kinetic and mechanical properties of transition metal nanoparticles loaded into various cement types were investigated sequentially. Firstly, metal nanoparticles, MNPs@CEM (M=Cu, Ni, Pd, Ru etc. and CEM= Cement types), were synthesized and their activity was tested for kinetic studies during the methanolysis of NaBH4 and it was found that the most active catalyst among them was nickel nanoparticles (NiNPs). Characterization of NiNPs@CEM was carried out using SEM, SEM-EDX, TEM, XRD, XPS, ATR-FTIR and UV-Vis spectroscopies. As a result of the kinetic studies, the calculated activation energies during the methanolysis of NaBH4 catalyzed by NiNPs@CEM-I and NiNPs@CEM-II were found to be Ea(NiNPs@CEM-I) =30.82 ± 2 kJ mol-1 and Ea(NiNPs@CEM-II) =24.34 ± 2 kJ mol-1; Activation enthalpies were calculated as ∆H#(NiNPs@CEM-I) =28.28 ± 2 kJ mol-1 and ∆H#(NiNPs@CEM-II) =21.79 ± 2 kJ mol-1 and standard activation entropies were calculated as ∆S#(NiNPs@CEM-I) =-134.95 + 5 J mol-1 K-1 and ∆S#(NiNPs@CEM-II) = -161.05 + 5 J mol-1 K-1, respectively. Furthermore, detailed kinetic studies were conducted on the heterogeneity, lifetime, reusability and isolability of NiNPs@CEM catalyzing the methanolysis of NaBH4. After kinetic studies, mechanical tests such as density, relative ultrasonic pulse velocity (UPV) and compressive strength tests were performed for NiNPs@CEM prepared in macro amounts and it was understood that NiNPs@CEM can also be used as building materials in various construction applications. NiNPs@CEM was found to be the most suitable material for both kinetic and mechanical studies. Therefore, in this thesis study, the prepared catalysts were used as building materials at the construction field after catalyzing the methanolysis of NaBH4. As a result, in this study, which consists of two consecutive stages, aims to gain new areas of use by loading transition metals into cement types.