Diglycerol synthesis via solvent-free selective glycerol etherification process over lithium-modified clay catalyst

• Diglycerol synthesis via solvent-free glycerol etherification.
• LiOH modification of acid-treated montmorillonite K-10.
• Elucidation of surface physicochemical properties.
• High diglycerol selectivity of 53% at 98% conversion.
• Improved selectivity of αβ diglycerol isomer with reduced αα isomers.

Diglycerol was synthesized via solvent free glycerol etherification over solid-base catalyst. Acid-treated montmorillonite K-10 (Clay MK-10) was modified with LiOH (Clay Li/MK-10) through ion-exchange method and characterized using different techniques for surface and structural properties. The parent and modified clay were then used to catalyze the production of diglycerol via solvent free glycerol etherification reaction. The reaction was conducted at 240 °C for up to 12 h and the activity of the catalysts was compared with that of homogeneous catalyst (LiOH). High diglycerol selectivity of about 53% was obtained at a glycerol conversion of about 98% with Clay Li/MK-10. The selectivity to αβ diglycerol isomer was also increased from 35% to 55% while the selectivity to αα isomer was decreased from 65% to 35%.

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