NaBH4'den Co KATALİZÖRLER ile HİDROJEN ÜRETİMİNE NaOH KONSANTRASYONU VE SICAKLIĞIN ETKİSİ
Project no. 1350 · Status: Kapanmış · 2017
Summary
ABSTRACT 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. The development of high performance, low cost catalysts is very important in large scale applications of NaBH4 hydrolysis. 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, the prepared Co2B and TiO2 were mixed and grinded in a planetary ball mill. The micrographs of the prepared composite catalysts were taken. NaBH4 alkali solution was prepared with NaOH for the hydrogen generation experiments. A 250 ml flask (with two openings, placed in a water bath) was used for the experiment and effects of different reaction temperatures were investigated by adjusting the water bath. 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 oC. 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 for 1:3 mole ratio Co2B/TiO2 composite catalysts, and this value is low when compared to previous studies, then, the prepared composite catalysts show superior catalytic activity for the hydrolysis of NaBH4. These composite catalysts introduced perfect catalytic properties and can undertake the applications in hydrogen generation and hydrogen storage. KEYWORDS: Hydrogen generation, composite catalyst, NaBH4, ball milling, Co catalyst.