Depolymerization of polystyrene over Mgx-Aly-O catalysts derived from hydrotalcites: Effect of Mg/Al ratio on the basicity and catalytic performance

•A series of hydrotalcite materials were prepared with a variation of Mg/Al ratio.•Hydrotalcites were calcined to obtain a set of Mgx-Aly-O catalysts with different Mg/Al ratio.•Depolymerization of polystyrene (PS) was conducted using Mgx-Aly-O catalysts.•Basicity was closely related to the catalytic performance of Mgx-Aly-O catalysts.•Catalytic performance increased with increasing basicity of Mgx-Aly-O catalysts.