Benefits of the SiO2-supported nickel phosphide catalyst on ethylene oligomerization

•The Ni2P/SiO2 catalyst exhibits the superior performance in ethylene oligomerization.•The particle size of Ni2P greatly influences the oligomerization activity.•The catalytic performance is affected by the Brønsted acid sites of Ni2P catalysts.•Ni2P/SiO2 is able to easily generate and transfer hydrogen species via POH groups.•The characteristics of Ni2P/SiO2 are beneficial for ethylene oligomerization.