Synthesis of nano-crystal PVMo2W9@[Cu6O(TZI)3(H2O)6]4•nH2O for catalytically biodiesel preparation

To develop efficient and reusable catalysts for biodiesel production, quaternary heteropolyacid H4PVMo2W9O40 (PVMo2W9) was effectively wrapped inside rht-MOF-1 {rht-MOF-1 = [Cu6O(TZI)3(H2O)6]4 center dot nH2O}, affording a crystalline H4PVMo2W9O40@rht-MOF-1 (1) by one-pot hydrothermal method. The identification of the crystal structure of 1 was achieved through the utilization of X-ray crystallography. Nano-size crystals of 1 (n-1) were prepared with the assistance of surfactant Tween 20. Notably, crystal n-1 was of cube shape grown along {100} facets rather than octahedral shape for 1. When n-1 was applied as the catalyst for the esterification reactions, high conversion rates were achieved. E. g. about 97 % conversion for oleic acid to the corresponding monoalkyl esters and about 87 % for rapeseed oil to biodiesel. The catalyst was heterogeneous and recyclable 7 times without obvious attenuation. Further, the correlation between the catalytic activity and structure of n-1 was investigated in terms of the distribution of active sites, various pores in rht-MOF-1, and the accessibility of catalytic sites on the {100} facets.

Automated summary

A novel catalyst, H4PVMo2W9O40@rht-MOF-1, was developed using a one-pot hydrothermal method. It exhibited high efficiency and reusability in esterification reactions.