Preparation of the efficient nano-bimetallic cobalt-nickel catalysts supported on the various magnetic substrates for hydrogen generation from hydrolysis of sodium borohydride in alkaline solutions

The heterogeneous catalytic hydrolysis of NaBH4 over the various bimetallic cobalt-nickel catalysts supported on the magnetic substrates was studied to understand their catalytic performances. Bentonite, zeolite (clinoptilolite), walnut based activated carbon, and Scharlau activated carbon (commercial sample) were used for the preparation of the magnetic catalysts. Despite the interest, no one to the best of our knowledge has studied the synthesize of the efficient bimetallic catalyst over the magnetic bentonite. The physico-chemical properties of the catalysts were evaluated by using XRD, FTIR, FESEM, TEM, BET, and VSM tests. The characterization of the catalysts indicated that the co-precipitation along with hydrazine is an appropriate method for the synthesis of the superparamagnetic nanoparticles over the porous substrates with sizes less than 30 nm. The highest magnetic strength was achieved to be 30.49 emu/g for the samples supported on the magnetic bentonite. The various operating conditions were also investigated including reaction temperature, NaOH, and NaBH4 content. The results illustrated that the hydrolysis of NaBH4 to hydrogen was a zero-order type reaction with respect to the NaBH4 content. The maximum hydrogen generation rate was measured to be 186 mL.min(-1).gcat(-1) in the presence of the bimetallic cobalt-nickel catalyst supported on the magnetic bentonite. The minimum activation energies were also calculated to be 37.62 and 44.98 kJ.mol(-1) over the samples supported on the magnetic zeolite and bentonite, respectively. The reusability of the catalyst was also investigated in six cycles. (C) 2020 Elsevier Ltd. All rights reserved.