Optimization of reaction conditions by response surface methodology for biodiesel production over different heterogeneous heteropoly acid-based nanomaterials

A series of nanocatalysts based on heteropoly acid supported on various nanomaterials such as metal-organic frameworks (MOFs), carbon- and silica-based materials, have been synthesized for application in the esterification of oleic acid as catalyst. The effects of multiple parameters and their reciprocal interactions were investigated using a five-level three-factor design. The reaction conditions such as catalyst amount, methanol to oleic acid molar ratio, and reaction temperature have been optimized by Response Surface Methodology using the Central Composite Design model. The reaction temperature was the most significant factor, and the best conversion ratio of oleic acid could reach 99.27% with 5.97% of catalyst amount and 3.90:1 of methanol to oleic acid molar ratio at 74.0 °C. As a preliminary application, the best nanocatalyst was used in biodiesel production from castor oil and methanol. The yields of fatty acid methyl esters for castor oil were about 90.2%.