Influence of Calcination Temperature on the Cooperative Catalysis of Base Sites and Gold Nanoparticles on Hydrotalcite-Supported Gold Materials for the Base-Free Oxidative Esterification of 1, 3-Propanediol with Methanol to Methyl 3-Hydroxypropionate

Magnesium–aluminum hydrotalcite (HT) supported gold catalyst (1 wt% Au/HT) was prepared by the colloid-deposition method and characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Hammett indicator method. The effects of calcination temperature of catalyst and support on the catalytic performance of aerobic oxidative esterification of 1,3-propanediol with methanol to methyl 3-hydroxypropionate (3-HPM) under base-free condition were studied. The results showed that the conversion of 1,3-propanediol and the selectivity of 3-HPM increased first and then decreased with the increase of calcination temperature of catalyst and support. The optimal calcination temperature of catalyst and support is 150 °C. Under the optimum preparation conditions, the conversion of 1,3-propanediol and the selectivity to 3-HPM are 96.2% and 94.9%, respectively. In addition, the 1 wt% Au/HT catalyst could be effectively recovered by calcining at 150 °C in air atmosphere, and the performance of the catalyst does not decrease significantly. The performance of the catalyst is higher than that reported previously. The structure of magnesium–aluminum hydrotalcite with appropriate density and medium strength base sites and small metallic Au particles are favorable for the selective oxidative esterification of 1,3-propanediol to 3-HPM. A 1 wt% magnesium–aluminum hydrotalcite supported gold catalyst (1 wt% Au/HT) was prepared by the colloid-deposition method. The calcination temperature plays an important role for the catalytic performance and the higher catalytic activity and product selectivity is due to the synergistic effect between the support structure with appropriate density and medium strength base sites and the smaller metallic gold particles.