Different Al/Ni ratios of pillared montmorillonite [Al/Ni (20, 15, 10, 6, 4, 2)-PILCs] were prepared by introducing the Al/Ni cationic polymers into montmorillonite under certain conditions. The structural properties of Al/Ni-PILCs were determined by a combination of X-ray diffraction (XRD), $$\hbox {N}_{2 }$$ N 2 adsorption–desorption, $$\hbox {NH}_{3}$$ NH 3 temperature programmed desorption ( $$\hbox {NH}_{3}$$ NH 3 -TPD) and scanning electron microscope (SEM). Structural characterizations showed the BET surface area and the interlayer spacing of Al/Ni-PILCs decreased regularly along with the nickel content. The weak acid sites of Al/Ni-PILCs increased compared with the Na-montmorillonite, and the strong acid sites decreased. The introduction of $$\hbox {Ni}^{2+}$$ Ni 2 + can adjust the acidity–basicity of the Al/Ni-PILC to some extent. In the reactions of the low-concentration ethanol dehydration, Al-PILC exhibited the highest catalytic activity with 93% ethanol conversion and 99% ethylene selectivity at $$500 {^{\circ }}\hbox {C}$$ 500 ∘ C .