Abstract

A novel catalytic technique is vital to produce mono- and dioleate (GMO and GDO) from bioglycerol: a renewable resource and by-product of biodiesel. The advantage of this invention is the direct production of GMO and GDO through catalytic approach compared to the conventional method that requires transesterification and distillation processes. In this paper, glycerol esterification with oleic acid using a catalyst was experimented. The process was carried out over a hydrophobic mesoporous zirconia–silica heterogeneous acid catalyst (ZrO₂–SiO₂–Me&Et–PhSO₃H) with three types of sulphated zirconia catalysts (SO₄²⁻/ZrO₂) to produce high-selectivity GMO and GDO products. The catalytic performance of the hydrophobic ZrO₂–SiO₂–Me&Et–PhSO₃H catalyst was benchmarked with that of SO₄²⁻/ZrO₂ which was developed from three zirconium precursors. Results showed that the pore volume and hydrophobicity of the designed catalyst greatly could influence the product selectivity, thus enabling smaller substrates GMO and GDO to be dominated in the synthesis. This finding was supported by characterisation data obtained through N₂ adsorption–desorption, X-ray diffraction and scanning electron microscopy. In addition, a good correlation was found between pore volume (pore size) and product selectivity. High pore volume catalyst favoured GDO production under identical reaction conditions. Pore volume and size can be used to control product sensitivity. The hydrophobicity of the catalyst was found to improve the initial reaction rate effectively.

Graphical abstract

摘要

一种新颖的催化技术对于从生物甘油生产单和二油酸酯（GMO和GDO）至关重要：生物柴油是可再生资源和副产物。与需要酯交换和蒸馏过程的常规方法相比，本发明的优点是通过催化方法直接生产GMO和GDO。本文尝试了使用油酸催化甘油酯化反应。该工艺是在疏水中孔氧化锆-二氧化硅多相酸催化剂（ZrO ₂ -SiO ₂ -Me＆Et-PhSO ₃ H）和三种硫酸化氧化锆催化剂（SO ₄ ^2- / ZrO _{2）上进行的}）生产高选择性的GMO和GDO产品。疏水性ZrO ₂ -SiO ₂ -Me＆Et-PhSO ₃ H催化剂的催化性能与由三种锆前体形成的SO ₄ ^2- / ZrO _2的性能进行了比较。结果表明，所设计催化剂的孔体积和疏水性极大地影响了产物的选择性，从而使较小的底物GMO和GDO在合成中占主导地位。通过N ₂获得的表征数据支持了这一发现吸附-解吸，X射线衍射和扫描电子显微镜。另外，在孔体积（孔径）和产物选择性之间发现了良好的相关性。高孔隙率催化剂有利于在相同的反应条件下生产GDO。孔的体积和大小可用于控制产品的敏感性。发现催化剂的疏水性有效地改善了初始反应速率。

图形概要