Heterogeneous esterification of ricinoleic acid with polyol for the synthesis of polyol ricinoleates as biomass‐based lubricant base oil

Abstract

Bio‐derived lubricants, especially those derived from vegetable oils, are considered to be promising alternatives to mineral oil‐based lubricants due to the features of sustainability and environmental friendliness. In this work, the polyol ricinoleates were prepared by esterification of ricinoleic acid with trimethylolpropane (TMP), neopentyl glycol (NPG) and pentaerythritol (PE) respectively using Lewis acidic stannous oxide as an efficient heterogeneous catalyst, affording the polyol ricinoleates up to 99.7% yield. Remarkably, the solid catalyst was readily recovered and reused at least for five cycles without significant loss of activity. The resulting polyol ricinoleates products were structurally characterized by Fourier transform infrared spectroscopy (FT‐IR), 1H NMR, 13C NMR, electrospray ionization mass spectra (ESI‐MS); and were stable below 300°C through thermogravimetric analysis (TGA). Furthermore, the physicochemical and lubricating properties of as‐synthesized polyol esters were also evaluated including viscosity at 40 and 100°C, viscosity index (VI), pour point and flash point, thermal stability and wear scar diameter. To our delight, the performance indicators of the target products were comparable or better than the commercial lubricants, showing their potential as lubricant base oil. This work represents an alternative access to useful lubricant products via effective and selective conversion of non‐edible vegetable oil.

Preparation of highly dispersed SnO/TiO2 catalysts and their performances in catalyzing polyol ester

“…Among these SnO/TiO 2 , 10% SnO/TiO 2 -Cl showed the best esterication performance with conversions of 91.2% and 99.6% at 2 h and 5 h, which was equivalent to or better than the catalytic esterication performance reported in the literature (Table 2). [29][30][31][32][33][34][35][36] By changing the Sn precursor from SnCl 2 $2H 2 O to SnC 2 O 4 , the conversion was reduced to 86.2% and 92.3% at 2 h and 5 h on 10% SnO/TiO 2 -ox. Then, the effect of Sn loading on the catalytic activity was investigated.…”