Ammonium Paratungstate Applied in The Catalyst for Utilization of Glycerol

Glycerol is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. It serves as a humectant, solvent, and sweetener, and may help preserve foods in food industries. It is even further used in in pharmaceutical and cosmetic industries.

One important and extensive source of glycerol is from biodiesel, which takes up 10 wt% of the whole production. as an unavoidable by-product which exceeds the current market demand, leading to a steady decline in price. Thus, the surplus glycerol is usually disposed off as waste which can pose a threat to the environment, especially water and air pollution.

The catalytic hydrogenolysis of glycerol to high-value 1,3-propanediol has received a great deal of attention. 1,3-propanediol is an essential platform chemical for producing polytrimethylene terephthalate (PTT) and polypropylene terephthalate (PPT), which mostly used in biodegradable polyester fibers, films, coatings, and engineering plastics. Accordingly, ammonium paratungstate has been applied in the catalyst named 5wt% Pt/WOx/L-Al2O3 for the transformation of glycerol to 1,3-propanedio, the highest 1,3-propanediol yield of 32.8% at 78% glycerol conversion.

The synthesis procedure is as below:

Al2O3 sample (average pore size 3.8 nm), ammonium paratungstate hydrate (APT ≥ 99.99%), and chloroplatinic acid hexahydrate (H2PtCl6·6H2O, ≥ 37.5% Pt basis) were used as purchased.

At first, WOx was impregnated on the different Al2O3 supports using an aqueous solution of ammonium paratungstate hydrate, with WOx loading of 15 wt% based on 1 g of Al2O3. The mixture was stirred at 60 °C for 4 h. After drying at 100 °C for 24 h, the WOx/Al2O3 samples were calcined at 800 °C for 2 h. The 5wt% Pt/WOx/Al2O3 catalysts were then prepared by impregnating WOx/Al2O3 samples with an aqueous solution containing desired amount of chloroplatinic acid hexahydrate. The slurry was thoroughly stirred at 60 °C for 4 h, after which it was dried overnight at 100 °C and then calcined at 400 °C for 4 h. The resulting catalysts were 5wt%Pt/WOx/Al2O3.

In conclusion, ammonium paratungstate has been applied in the catalyst for hydrogenolysis of glycerol to 1,3-propanediol yield, the highest 1,3-propanediol yield of 32.8% at 78% glycerol conversion were obtained over 5wt% Pt/WOx/L-Al2O3 catalyst. The highest 1,3-propanediol yield of 32.8% at 78% glycerol conversion were obtained over 5wt% Pt/WOx/L-Al2O3 catalyst under reaction condition of 220 °C, 6 MPa, 5 h reaction time and amount of catalyst to glycerol ratio of 0.25 g mL−1.

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