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Silpakorn University Science and Technology Journal, 10, 2

In this work, effects of catalysts (TiO2, and Nb2O5) were investigated on the hydrogen desorption of Mg(BH4)2. LiBH4 and MgCl2 with 2:1 molar ratio were mixed by using ball milling to prepare Mg(BH4)2. The desorption behaviors were measured by thermo-volumetric apparatus. The hydrogen desorption capacity of the mixed sample milled for 2 h was 4.78 wt% with a 2-step released. The first step occurred at 214 °C and the second step appeared at 374 °C. The addition of 16 wt% Nb2O5 decreased the desorption temperature in the second step about 66 °C and increased the hydrogen desorption capacity to 4.86 wt% hydrogen. The addition of TiO2 also improved the desorption temperature in the second step and the hydrogen desorption capacity. It decreased the desorption temperature about 71°C and showed a high amount of hydrogen, 5.27 wt%, released from the mixed sample. The hydrogen absorption after desorption of Mg(BH4)2 was also studied under 9.5 MPa and 350 °C for 12 h., {"references":["Ye, X., An, Y., and Xu, G. (2011). Kinetics of 9 -\nethylcarbazole hydrogenation over Raney-Ni catalyst for\nhydrogen storage. Journal of Alloys and Compounds, 509,\n152-156.","Dong, J., Wang, X., Xu, H., Zhao, Q., and Li., J. (2007).\nHydrogen storage in several microporous zeolites.\nInternational Journal of Hydrogen Energy, 32, 4998-5004.","Hu, X., Fan, M., Towler,B.F., Radosz M., and Bell, D. A.\n(2011). Chapter 8 Hydrogen Adsorption and Storage. Coal\nGasification and Its Applications., 188.","Sakintuna, B., Darkrimb, F. L., Hirscherc, M. (2007). Metal\nhydride materials for solid hydrogen storage: A review.\nInternational Journal of Hydrogen Energy, 32, 1121-1140.","Pistidda, C., Garroni, S., Dolci, F., Bardaj├¡, E. G., Khandelwal,\nA., Nolis, P., Dornheim, M., Gosalawit, R., Jensen, T.,\nCerenius, Y., Suriñach, S., Baro, M. D., Lohstroh, W., and\nFichtner, M. (2010). Synthesis of amorphous Mg(BH4)2 from\nMgB2 and H2 at room temperature. Journal of Alloys and\nCompounds, 508, 212-215.","Zhang, Z.G., Zhang, S.F., Wang, H., Liu, J.W., and Zhu, M.\n(2010). Feasibility study of the direct synthesis of Mg(BH4)2\ncomplex hydrides by mechanical milling. International Journal\nof Hydrogen Energy, 505, 717-721.","Matsunaga, T., Buchter, F., Miwa, K., Towata, S., Orimod, S.,\nand Züttel, A. (2008). Magnesium borohydride: A new\nhydrogen storage. Renewable Energy, 33, 193-196.","Matsunaga, T., Buchter, F., Mauron, P., Bielman, M.,\nNakamori, Y., Orimoc, S., Ohba, N., Miwa, K., Towata, S., and\nZüttel, A. (2008). Hydrogen storage properties of Mg(BH4)2.\nJournal of Alloys and Compounds, 459, 583-588.","Li, H.-W., Kikuchi, K., Nakamori, Y., Miwa K, Towata, S., and\nOrimo, S. (2008). Effects of ball milling and additives on\ndehydriding behaviors of well-crystallized Mg(BH4)2. Scripta\nMaterialia, 57, 679-682.\n[10] Friedrichs, O., Klassen, T., Sánchez-López, J.C., Bormann, R.,\nFernández, A. (2006). Hydrogen sorption improvement of\nnanocrystalline MgH2 by Nb2O5 nanoparticles. Scripta\nMaterialia, 54, 1293-1297."]}

To reduce the carbon dioxide emission into the atmosphere, adsorption is believed to be one of the most attractive methods for post-combustion treatment of flue gas. In this work, activated carbon (AC) was modified by polyethylenimine (PEI) via impregnation in order to enhance CO2 adsorption capacity. The adsorbents were produced at 0.04, 0.16, 0.22, 0.25, and 0.28 wt% PEI/AC. The adsorption was carried out at a temperature range from 30 °C to 75 °C and five different gas pressures up to 1 atm. TG-DTA, FT-IR, UV-visible spectrometer, and BET were used to characterize the adsorbents. Effects of PEI loading on the AC for the CO2 adsorption were investigated. Effectiveness of the adsorbents on the CO2 adsorption including CO2 adsorption capacity and adsorption temperature was also investigated. Adsorption capacities of CO2 were enhanced with the increase in the amount of PEI from 0.04 to 0.22 wt% PEI before the capacities decreased onwards from0.25 wt% PEI at 30 °C. The 0.22 wt% PEI/AC showed higher adsorption capacity than the AC for adsorption at 50 °C to 75 °C.