Brønsted acid-functionalized silica-coated magnetic catalyst for the preparation of polyol ricinoleates

As a kind of non-edible vegetable oil, castor oil has attracted considerable interest in developing bio-based products due to its unique structure, among which polyol ricinoleates are considered as promising alternatives to mineral oil-based lubricants. In this article, a Brønsted acid-functionalized silica-coated magnetic catalyst (Fe 3 O 4 @SiO 2 -IM-SO 3 H) was developed as the efficient heterogeneous catalyst for the preparation of polyol ricinoleates via the esterification of ricinoleic acid with trimethylolpropane (TMP), neopentyl glycol (NPG), and pentaerythritol (PE), respectively. The structure and magnetic property of the catalyst were characterized by Fourier infrared spectroscopy (FT-IR), X-ray diffractometer technology (XRD), element analysis (CHN), and vibrating sample magnetometer (VSM). As a result, the sulfonic group was proposed to promote the esterification and the magnetism facilitated the catalyst separation. Notably, the yield of polyol ricinoleates attained successfully up to 99.5%, and the catalyst was recycled for at least five times without obvious activity reduction. This work about the utilization of magnetic nanoparticles supported acid catalysts in polyol ricinoleates preparation features clean and sustainability, providing an example of developing green products.