Hydrogen production by chemical looping steam reforming of ethanol using NiO/montmorillonite oxygen carriers in a fixed-bed reactor

• Novel OCs of NiO/MMT for CLSR were prepared by ultrasound impregnation.
• MMT in NiO/MMT OCs effectively control particles distribution and enhance OT and WGS.
• Dead time for CLSR to H2 during fuel feeding step was shorten by NiO/MMT OCs.
• Activity and stability of NiO/MMT with 20% NiO for multi-cycles CLSR were high.

Hydrogen production by chemical looping steam reforming of ethanol using oxygen carriers was carried out in a fixed-bed reactor. NiO/montmorillonite prepared by ultrasound assisted cation exchange impregnation method was used as oxygen carriers. The synthesized NiO/montmorillonite was characterized by N2 adsorption–desorption, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), H2 pulse chemisorption, temperature-programmed reduction (TPO) and thermal gravimetric analysis (TGA). The characterization results showed the particle size, metal-support interaction, nickel dispersion interrelated with cation exchange capability and confinement effect of montmorillonite’s lamellar structure. Activity and stability tests were conducted at 550 °C with a steam to carbon ratio of 4. The results showed that 20Ni–MMT possessed the best performance due to its strong sintering and coking resistance, and also presented the shortest ‘dead time’ due to its larger active surface area. Moreover, 20Ni–MMT exhibited the excellent coke elimination ability in the air feed step.