A series of highly active, selective, and stable solid indium-exchanged tungstophosphoric acid catalysts had been prepared, characterized and evaluated for bio-derived glycerol esterification with acetic acid to produce valuable biofuel additives. It was found that the Inx/3H3−xPW with nanotube structure owns Lewis acidity and Brønsted acidity in one, which favors for the efficient esterification of glycerol into monoglycerides with higher selectivity. Among all, In0.8H0.6PW presented exceptionally high activity with 88 % conversion and 96 % selectivity to MAG within 30 min of reaction time at 120 °C using 4:1 molar ratio. The better performance came from its remarkable stability, due to the unique Keggin structure, high acidity as well as nanotube structure. In addition, this In0.8H0.6PW catalyst did not suffer from deactivation of water in the six consecutive reaction tests.
Heteropolyacids Nanotube Brønsted acidity Lewis acidity Esterification
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This work was supported by the National Natural Science Foundation of China (20871026). Supported by “the Fundamental Research Funds for the Central Universities” (10JCXK011). Supported by the major projects of Jilin Provincial Science and Technology Department (20140204085GX).