Cobalt borid katalizörleri ile Sodyum Borohidritten hidrojen üretimi

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. 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.

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.