Pt/Au/WO3 Catalysts Prepared from Ammonium Paratungstate

Glycerol is a byproduct of overcapacity from biodiesel manufacture. Selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) has seen an increasing industrial demand as the glycerol derived from biodiesel production. By the way, 1,3-PDO has been largely utilized in solvents, cosmetics, cleaning products, pharmaceutical industries, and organic synthesis intermediates.

Unfortunately, the selective formation of 1,3-PDO from glycerol has its drawbacks due to the thermodynamics and steric hindrance. To get over the drawbacks, Pt was doped with Au/WO3. Pt/Au/WO3 catalysts was produced with ammonium paratungstate (APT) as tungsten source for WO3. Higher dispersion, higher surface enrichment and higher electron density of Pt had made the Pt/Au/WO3 catalysts to get excellent efficiency in selective hydrogenolysis of glycerol to 1,3-PDO.

The production method of Pt/Au/WO3 catalysts is as following steps:

2.7 g of ammonium paratungstate (APT) was first dissolved in 90 mL of water at 90 °C and stirred magnetically. After cooling down to room temperature, a certain amount of aqueous solution of HCl was added dropwise to adjust the solution pH to 0.9. After continuous stirring for 0.5 h, 1.2 g of CTAB was added and stirred for another 30 min.

Then, an aqueous solution of HAuCl4 was added to the above solution. The suspension was aged for 24 h before the solid was recovered by filtering and washing. The solid was further dried at 110 °C overnight, and calcined at 500–650 °C for 3 h to obtain Au/WO3samples where the Au content was fixed at 0.1 wt%. Subsequently, the Au/WO3 samples were impregnated with an aqueous solution of H2PtCl6·6H2O, followed by calcination at 300 °C for 1 h and reduction in flowing H2 at 300 °C for 1 h to obtain the Pt/Au/WO3-T catalysts, where the Pt content was fixed at 2 wt%.

In summary, Pt/Au/WO3 catalysts were successfully prepared using APT as tungsten source, the conversion rate of conversion of glycerol to 1,3-PDO could reach 54.4%. The increased low-valence state of W and Pt had contributed to the conversion of glycerol to 1,3-PDO, leading to enhancement in both glycerol conversion and 1,3-PDO selectivity compared with Pt/WO3.

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