Hydrogen generation from NaBH₄ hydrolysis using Co-B/AlPO₄ and Co-B/bentonite catalysts

Abstract

Aluminium phosphate and bentonite supported Co-B catalyst were synthesized via two step impregnation-reduction method for sodium borohydride hydrolysis. The synthesized catalysts were characterized by XRD, FTIR, XPS, FE-SEM, FE-TEM, BET, ICP-AES techniques and tested for NaBH 4 hydrolysis reaction. The results demonstrated that the synthesized supported Co-B catalysts greatly facilitate the NaBH 4 hydrolysis reaction. Highest hydrolysis rate observed for Co-B/AlPO 4 and Co-B/bentonite catalysts are 6.50 and 3.91 L min −1 g −1 , respectively, with 2 wt% NaBH 4 , 5 wt% NaOH solution at 30 °C. The hydrogen generation rate was found to increase with experimental temperature. Activation energy for the hydrolysis reaction was observed to be 37 and 40.2 kJ mol −1 for Co-B/AlPO 4 and Co-B/bentonite catalysts, respectively.

Efficient Hydrogen Generation from the NaBH4 Hydrolysis by Cobalt-Based Catalysts: Positive Roles of Sulfur-Containing Salts

“…For instance, distinguishable impact on the reactivity of the Co 3 O 4 -CC catalyst was identified between the addition of Na 2 S and Na 2 SO 4 , achieving up to 5-fold difference in HGR. Noteworthy, in our case, the catalytic hydrogen production obtained good results under relatively mild conditions concerning a lower temperature (25 °C) and small catalyst usage (0.02 g), in contrast with previous works. ,,, For example, the hydrogen generation rate of a selected sulfur-containing cobalt-based catalyst (precursor mixture, CoSO 4 /Na 2 S = 4:4) is ∼4425 mL·min –1 ·g cat –1 , which is 3.6 or 4.37 times active than that of cobalt oxide with a calculated HGR of ∼1230 mL·min –1 ·g cat ‑1 in ref and ∼1013 mL·min –1 ·g cat –1 in ref (condition: 40 °C, m cat. = 0.0117 g).…”

“…= 0.5 g). In terms of comprehensive evaluation, the screened catalysts in our paper are more reactive than those reported by Shharma et al In short, the addition of Na 2 S and Na 2 SO 4 remarkably improves the hydrogen production activity of previous sulfur-free catalysts in our work.…”

“…Noteworthy, in our case, the catalytic hydrogen production obtained good results under relatively mild conditions concerning a lower temperature (25 °C) and small catalyst usage (0.02 g), in contrast with previous works. 31,34,56,57 For example, the hydrogen generation rate of a selected sulfurcontaining cobalt-based catalyst (precursor mixture, CoSO 4 / Na 2 S = 4:4) is = 0.5 g). In terms of comprehensive evaluation, the screened catalysts in our paper are more reactive than those reported by Shharma et al 57 In short, the addition of Na 2 S and Na 2 SO 4 remarkably improves the hydrogen production activity of previous sulfur-free catalysts in our work.…”

“…31,34,56,57 For example, the hydrogen generation rate of a selected sulfurcontaining cobalt-based catalyst (precursor mixture, CoSO 4 / Na 2 S = 4:4) is = 0.5 g). In terms of comprehensive evaluation, the screened catalysts in our paper are more reactive than those reported by Shharma et al 57 In short, the addition of Na 2 S and Na 2 SO 4 remarkably improves the hydrogen production activity of previous sulfur-free catalysts in our work. Dramatically, we found that only in the catalyst preparation procedure, the addition of sulfur-containing sodium salts obviously enhanced the reactivity of the as-synthesized Co 3 O 4based catalysts (see Figures 6 and 7); whereas, adding Na 2 SO 4 or Na 2 S hardly accelerates the HGR only during the catalytic reaction system (not shown here).…”

Challenges in the use of hydrogen for maritime applications

“…To deal with this self-inhibition of the reaction, catalysts have been developed, usually based on cobalt. [152][153][154] On the side of hydrogen release NaBH 4 has many advantages for hydrogen release, but the reverse reaction is very difficult to perform efficiently. The boron-oxygen bonds are very stable, and thus difficult to rehydrogenate directly.…”