Fluidization characteristics of fine cohesive particles assisted by vertical vibration in a fluidized bed reactor

•Fluidization under vibration does not agglomeration and sintering of fine cohesive particles.•Temperature influences both the pressure drop and mass loss.•An increase in temperature enables the rate of reduction kinetics to reach 99% over a short time.•The product exhibiting an excellent reduction reaction has a porous surface. This research has examined fluidization and product characteristics through hydrogen reduction for nickel oxide (NiO) of contained in the Geldart group C assisted by vertical vibration in a fluidized bed reactor. It has confirmed that as vibration frequency and reaction temperature increase, the pressure drop trend becomes stable and minimum fluidization velocity reduces. As the gas–solid reaction increased with the increase in reaction temperature, oxygen contained in NiO was removed with a fast reaction time and therefore, the mass loss drastically decreased. When reaction temperature increased, the reacted fraction quickly increased because of the short reaction time. In the case of fluidization that was not under vibration, SEM and TEM analysis of the products showed agglomeration and chemical bonding. However, with a vibration, no agglomeration occurred, and a porous surface appeared. For fluidization under vibration, energy-dispersive X-ray spectroscopy and mapping analysis of products showed that the oxygen content and distribution decreased, and a small amount of oxygen remained surrounding the product surface. Agglomeration occurred again at higher values, with a superficial gas velocity of 0.45 m/s and vibration frequency of 60 Hz. It has also confirmed that the vertical vibration relieves the forces between fine cohesive particles to eliminate agglomeration and give them an active fluidization state.