Hydrotalcite Supported Pt Catalyst For Glycerol Oxidation

Glycerol, the by-product of biological diesel oil, is an important building block platform for biomass conversion. The catalytic oxidation of glycerol to value-added compounds, such as glyceraldehyde, glyceric acid, tartronic acid, dihydroxy acetone and hydroxypyruvic acid, is an effective way to improve the economy of bio diesel process and a promising route for industrial biomass utilization as well. In this thesis, aiming at designing highly efficient Pt catalysts for oxidation of glycerol, a comparative study has been made on the structure and catalytic performance of four Pt catalysts over supports with different surface properties. Furthermore, Mg-Al Hydrotalcite was the selected as the best catalyst support for glycerol oxidation and its preparation condition was also optimized. The main results are as follows:(1) A comparative study on the structure and performance of Pt/HTC, Pt/CNTs, Pt/Al2O3 and Pt/MgO shown that the surface chemistry of supports has a significant effect on the catalytic performance of Pt catalysts in glycerol oxidation, particularly on the distribution of oxidation products. The commercial hydrotalcite supported Pt catalyst (Pt/HTC) has a better Pt dispersion and appropriate basic sites to achieve the highest glycerol conversion (62%) and total C3 product yield;(2) Pt catalyst supported on lab-made hydrotalcite (Pt/HT) showed much better activity of 90% glycerol conversion than the commercial hydrotalcite supported Pt catalyst (Pt/HTC). Unfortunately, the stability of the former is not as good as that of the latter. Calcination treatment can effectively enhance the stability of the Pt/HT catalyst, but with a decreased activity. It is further indicated that basic sites on support surface could be regulated by varying the Mg/Al ratio and calcination temperature, and hence the corresponding catalytic performance of Pt catalysts for glycerol oxidation;(3) Compared with physically mixed Mg-Al oxides, the Mg-Al hydrotalcite has larger surface area and more suitable basic sites because the Al atoms are highly dispersed in the crystal lattice of MgO after calcination. Therefore, the Mg-Al hydrotalcite supported Pt catalyst has better activity and selectivity to the value-added C3 products, which make it a promising catalyst in glycerol oxidation for industrial application.