• PDF / 355,042 Bytes
• 10 Pages / 595.22 x 842 pts (A4) Page_size
• 39 Downloads / 264 Views

DOWNLOAD

REPORT

---

Hydrogen Storage in Ti-Zr Based Systems J. Salmones1, B. Zeifert2, M. Ortega-Avilés3, J. L. Contreras-Larios4, V. Garibay-Febles5 1 Instituto Politécnico Nacional, Laboratorio de Catálisis y Materiales, ESIQIE. C.P. 07738, México D. F. e-mail: [email protected] 2 Instituto Politécnico Nacional, DIM, ESIQIE, UPALM, C.P. 07738, México D. F. 3 Instituto Politécnico Nacional, Centro de Nanociencia y Micro Nanotecnología, UPALM, C.P. 07738, México D. F. 4 Universidad Autónoma Metropolitana, Av. San Pablo 180. C.P. 02200, México D. F. 5 Instituto Mexicano del Petróleo, LMEUAR, Eje Central L. Cárdenas No. 152, 07730, D.F. México. ABSTRACT This research contributes to the study of hydrogen storage of two Ti-Zr based systems using (I) titanium dioxide (TiO2) + zirconium acetylacetonate (C20H28O8Zr) and (II) titanium dioxide (TiO2) + zirconium tetrachloride (ZrCl4) as starting materials. Both systems were prepared by mechanical grinding under the same conditions, with composition of 50 wt.% Ti and Zr and milling time of 2, 5, 7, 15, 30 and 70 hrs. The samples were evaluated by hydrogen absorption tests and characterized by BET, XRD and TEM. The results of hydrogen storage at different pressures but same temperature showed that samples of the system I absorbed the largest quantities of hydrogen but difficult to release them, while the system II absorbed less amount of hydrogen but completely desorbed the absorbed hydrogen. The increase of the mechanical grinding time is directly associated with changes in hydrogen absorption capacity and formation of new components. The formation of oxide nanoparticles of Ti and Zr on the surface of TiO2 in samples from series II was associated with the hydrogen absorption capacity. Keywords: hydrogen storage, Ti-Zr, mechanical milling, sorption. INTRODUCTION The annual world energy demand, estimated to be around 10,000 million tons of oil equivalents, is covered by more than 87% by fossil fuels like coal, oil, and natural gas [1]. This fuel dependence has important implications for both economic and environmental aspects [2-4]. Likewise, in the absence of viable alternatives, the depletion of oil reserves, estimated to happen in no more than 40 years, will greatly affect the overall economic development in the future. Hydrogen has been considered a suitable, clean, and affordable fuel; it can be produced from a wide variety of energy sources, such as natural gas, coal, biomass, water, sewage, solid waste, tires and waste oil. It is also considered as the fuel of the future because it is the most abundant element in nature, the lightest (highest energy content per unit mass) and the cleanest when combusting with oxygen, generating water as a product. However, compared with other fossil fuels (such as oil or coal), hydrogen stores the least amount of energy per unit volume at ambient conditions. Hydrogen production is not a problem, because despite it is still being worked on a range of options, researchers have already known many ways in which this fuel can be obtained. The

problem