HYDROGEN GENERATION FROM SODIUM BOROHYDRIDE WITH COBALT BORIDE CATALYSTS

Öz

NaBH4 is a promising hydrogen storage material, with its high hydrogen storage capacity (10.8 wt%), stability in alkaline solutions, mild reaction temperature, nontoxic by products and controllable hydrogen generation rates. Hydrogen generation of NaBH4 was investigated with Co2B/TiO2 composite catalyst. Co catalysts are very good candidates for NaBH4 hydrolysis from economical viewpoint. Composite catalysts have attracted continuous interest during the past decades and enable to give high selectivity, high activity and good stability. In this study, 1:1, 1:2, 1:3 and 1:4 molar ratio of Co2B/TiO2 composite catalysts were prepared to study hydrogen generation effects. Firstly, Co2B was produced with NaBH4 and CoCl2. Then, Co2B and TiO2 were mixed and grinded in a planetary ball mill. A 250 ml flask (with two openings, placed in a water bath) was used for the experiment. Alkaline NaBH4 solution and prepared catalysts were used and hydrogen generation rate was measured with the adjusted inverted burette which was submerged to the water at room temperature. 1:3 mole ratio composite catalysts gave the highest hydrogen generation rate as 364.58 ml.g-1.min-1 with 0.3 g catalyst amount, 2 wt% NaOH concentration, 9 wt% NaBH4 concentration and at 35 ○C. The effects of catalyst amount, NaOH and NaBH4 compositions, reaction temperature on the hydrogen generation rate were investigated and kinetic rate expression was determined. The calculated activation energy was 36.50 kJ.mol-1 , this value is low when compared to previous studies. These composite catalysts introduced perfect catalytic properties and can undertake the applications in hydrogen generation and hydrogen storage.

Anahtar Kelimeler

• hydrogen generation
• composite catalyst
• NaBH4
• ball milling
• cobalt boride catalysts

COBALT BORİD KATALİZÖRLERİ İLE SODYUM BOROHİDRİTTEN HİDROJEN ÜRETİMİ

Öz

NaBH4 is a promising hydrogen storage material, with its high hydrogen storage capacity (10.8 wt%), stability in alkaline solutions, mild reaction temperature, nontoxic by products and controllable hydrogen generation rates. Hydrogen generation of NaBH4 was investigated with Co2B/TiO2 composite catalyst. Co catalysts are very good candidates for NaBH4 hydrolysis from economical viewpoint. Composite catalysts have attracted continuous interest during the past decades and enable to give high selectivity, high activity and good stability. In this study, 1:1, 1:2, 1:3 and 1:4 molar ratio of Co2B/TiO2 composite catalysts were prepared to study hydrogen generation effects. Firstly, Co2B was produced with NaBH4 and CoCl2. Then, Co2B and TiO2 were mixed and grinded in a planetary ball mill. A 250 ml flask (with two openings, placed in a water bath) was used for the experiment. Alkaline NaBH4 solution and prepared catalysts were used and hydrogen generation rate was measured with the adjusted inverted burette which was submerged to the water at room temperature. 1:3 mole ratio composite catalysts gave the highest hydrogen generation rate as 364.58 ml.g-1.min-1 with 0.3 g catalyst amount, 2 wt% NaOH concentration, 9 wt% NaBH4 concentration and at 35 ○C. The effects of catalyst amount, NaOH and NaBH4 compositions, reaction temperature on the hydrogen generation rate were investigated and kinetic rate expression was determined. The calculated activation energy was 36.50 kJ.mol-1 , this value is low when compared to previous studies. These composite catalysts introduced perfect catalytic properties and can undertake the applications in hydrogen generation and hydrogen storage.

Anahtar Kelimeler

• hidrojen üretimi
• kompozit katalizör
• NaBH4
• bilyalı öğütme

Kaynakça

1. REFERENCES [1] Bagheri S., Julkapli N. M., and Hamid S. B. A. (2014). “Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis”. The Scientific World Journal, Article ID 727496, 1-21. https://doi.org/10.1155/2014/727496
2. [2] Dai H.-B., Ma G.-L., Xia H.-J. and Wang P. (2011). “Combined Usage of Sodium Borohydride and Aluminum Powder for High-performance Hydrogen Generation”. Fuel Cells 11(3), 424–430. https://doi.org/10.1002/fuce.201100015
3. [3] Demirci U. B. and Miele P. (2010). “Cobalt in NaBH4 hydrolysis”. Phys. Chemistry Chemical Physics 12, 14651–14665. https://doi.org/10.1039/C0CP00295J
4. [4] Inokawa H., Driss H., Trovela F., Miyaoka H., Ichikawa T., Kojima Y., Zaman S. F., Al-Zahrani A., Alhamed Y. and Petrov L. (2016). “Catalytic hydrolysis of sodium borohydride on Co catalysts”. International Journal of Energy Research 40, 2078–2090. https://doi.org/10.1002/er.3582
5. [5] Kaur A., Gangacharyulu D. and Bajpai P.K. (2016). “Kinetic studies on the NaBH4/H2O hydrogen storage system with CoCl2 as a catalyst”. Bulgarian Chemical Communications 48 (2), 290 – 296. http://www.bcc.bas.bg/BCC_Volumes/Volume_48_Number_2_2016/BCC-48-2-2016-3895-Kaur-290-296.pdf
6. [6] Liang, Z.; Li, Q.; Li, F.; Zhao, S. and Xia, X. (2017). “Hydrogen generation from hydrolysis of NaBH4 based on high stable NiB/NiFe2O4 catalyst”. International Journal of Hydrogen Energy 42, 3971–3980. https://doi.org/10.1016/j.ijhydene.2016.10.115
7. [7] Liua C.-H., Chen B.-H., Hsueh C.-L., Kub J.-R., Jengb M.-S. and Tsau F. (2009). “Hydrogen generation from hydrolysis of sodium borohydride using Ni–Ru nanocomposite as catalysts”. International Journal of Hydrogen Energy 34, 2153-2163. https://doi.org/10.1016/j.ijhydene.2008.12.059
8. [8] Ma, H.; Ji, W.; Zhao, J.; Liang, J.; Chen, J. (2009). “Preparation, characterization and catalytic NaBH4 hydrolysis of Co-B hollow spheres”. J. Alloys Compd. 474, 584–589. https://doi.org/10.1016/j.jallcom.2008.07.005

9. [9] Patel N., Fernandes R. and Miotello A.. (2010). “Promoting effect of transition metal-doped Co–B alloy catalysts for hydrogen production by hydrolysis of alkaline NaBH4 solution”. Journal of Catalysis 271, 315–324. https://doi.org/10.1016/j.jcat.2010.02.014
10. [10] Wang H., Lu J., Dong S. J., Chang Y., Fu Y. G. and Luo P. (2014). “Preparation and Hydrolysis of Aluminum Based Composites for Hydrogen Production in Pure Water”. Materials Transactions 55 (6), 892 – 898. https://doi.org/10.2320/matertrans.M2013425
11. [11] Wei Y., Meng W., Wang Y., Gao Y., Qi K. And Zhang K. (2017). “Fast hydrogen generation from NaBH4 hydrolysis catalyzed by nanostructured Co-Ni-B catalysts”. International Journal of Hydrogen Energy 42, 6072-6079. https://doi.org/10.1016/j.ijhydene.2016.11.134
12. [12] Wu, Z.; Ge, S. (2011). “Facile Synthesis of a Co–B nanoparticle catalyst for efficient hydrogen generation via borohydride hydrolysis”. Catal. Commun. 13(1), 40–43. https://doi.org/10.1016/j.catcom.2011.06.017
13. [13] Xiang C., Jiang D., She Z., Zou Y, Chu H., Qiu S., Zhang H., Xu F., Tang C. and Sun L. (2015). “Hydrogen generation by hydrolysis of alkaline sodium borohydride using a cobalt-zinc-boron/ graphene nanocomposite treated with sodium hydroxide”. International Journal of Hydrogen Energy, 40, 4111–4118. https://doi.org/10.1016/j.ijhydene.2015.01.145
14. [14] Xu D., Dai P., Liu X., Cao C., Guo Q. (2008). “Carbon-supported cobalt catalyst for hydrogen generation from alkaline sodium borohydride solution”. Journal of Power Sources 182, 616-620. https://doi.org/10.1016/j.jpowsour.2008.04.018
15. [15] Ye W., Zhang H., Xu D., Ma L. and Yi B. (2007). “Hydrogen generation utilizing alkaline sodium borohydride solution and supported cobalt catalyst”. Journal of Power Sources 164, 544-548. https://doi.org/10.1016/j.jpowsour.2006.09.114
16. [16] Zhang X., Wei Z., Guo Q., Tian H. (2013). “Kinetics of sodium borohydride hydrolysis catalyzed via carbon nanosheets supported Zr/Co”. Journal of Power Sources 231, 190-196. https://doi.org/10.1016/j.jpowsour.2013.01.008
17. [17] Zhao, J.; Ma, H.; Chen, J. (2007). “Improved hydrogen generation from alkaline NaBH4 solution using carbon-supported Co–B as catalysts”. International Journal of Hydrogen Energy 32, 4711–4716. https://doi.org/10.1016/j.ijhydene.2007.07.004
18. [18] Zou Y., Gao y., Huang P., Xiang C., Chu H., Qiu S., Yan E., Xu F. and Sun L. (2017). “Effects of the Preparation Solvent on the Catalytic Properties of Cobalt–Boron Alloy for the Hydrolysis of Alkaline Sodium Borohydride”. Metals 7, 365-376. https://doi.org/10.3390/met7090365