Improved propylene selectivity and superior catalytic performance of Ga-xMg/ZSM-5 catalysts for propane dehydrogenation (PDH) reaction

In recent years, Ga-based catalysts attract much attention in propane dehydrogenation (PDH) reaction due to environmental friendliness and low cost. Nevertheless, it is still challenging to obtain high selectivity of propylene under harsh reaction conditions. In this work, the supported catalysts (Ga-xMg/ZSM-5) were prepared with the sequential impregnation method and applied in the PDH reaction. The results show that MgO as an additive reduces the acidity of the catalysts, promotes the dispersion of Ga2O3 and improves the selectivity of propylene. As a result, the average particle size of the Ga/ZSM-5 catalyst is larger (4.5 nm), and the initial propylene selectivity is only 71.0 %. In contrast, the optimal Ga-0.7Mg/ZSM-5 catalyst shows the smallest particle size (2.4 nm) and the highest propylene selectivity of 90.8 %. In comparison with the previous GaOx catalysts in literatures, the Ga-0.7Mg/ZSM-5 catalyst exhibits a superior production rate of propylene (rC3H6) based on either catalyst weight or Ga2O3 weight.