Effect of MgO on the catalytic performance of MgTiO3 in urea alcoholysis to propylene carbonate

• Preparation and characterization of MgTiO3 catalyst.
• Synergistic effect between MgTiO3 and MgO improved the catalytic activity.
• The amount of aggregated MgO on the surface of MTO-1.0 was the maximum.
• The loss of MgO leaded the catalytic activity to decrease.

The perovskite MgTiO3 catalyst was prepared by the sol–gel method and characterized by X-ray diffraction (XRD), temperature-programmed desorption of CO2 (CO2-TPD) and energy dispersive spectroscopy (EDS). The catalytic behavior was also investigated for the urea alcoholysis to propylene carbonate (PC). It was found that the preparation conditions of MgTiO3, including calcination temperature, calcination time and Mg/Ti molar ratio, affected the aggregation of MgO on the surface of MgTiO3. Aggregated MgO could promote a synergistic effect with MgTiO3 to change the basic performances on the surface, which resulted in the activity difference. When MgTiO3 was prepared at calcination temperature of 700 °C, the calcined time of 3 h and the Mg/Ti molar ratio of 1.0, the synergistic effect was the strongest, which led to the highest activity. The yield and the selectivity of PC were up to 93.5% and 99.0%, respectively. An increased number of reuse of the catalyst, resulted in a loss of MgO from the catalyst surface, thereby reducing the overall catalytic activity.