Modulation of Self-Separating Molecular Catalysts for Highly Efficient Biomass Transformations.

Area of Science:

• Catalysis
• Materials Science
• Biomass Conversion

Background:

• Developing stable and efficient solid acid catalysts is crucial for large-scale biomass resource transformation.
• Classical Dawson polyoxometalates (POMs) are being explored for catalytic applications.
• Sulfonic acid functionalization is a key strategy for enhancing catalyst acidity.

Purpose of the Study:

• To covalently modify Dawson polyoxometalates (POMs) with sulfonic acid groups.
• To synthesize and characterize a novel solid acid catalyst, TBA₆-P₂W₁₇-SO₃H.
• To evaluate the catalyst's performance in the esterification of free fatty acids (FFA) for biodiesel production.

Main Methods:

• Covalent grafting of sulfonic acid groups onto the POM surface via (3-mercaptopropyl)trimethoxysilane.
• Characterization of catalyst acidity using ³¹P NMR spectroscopy.
• Assessment of catalytic activity, selectivity, and stability in FFA esterification.

Main Results:

• TBA₆-P₂W₁₇-SO₃H exhibits strong Brønsted acid sites, confirmed by ³¹P NMR.
• The catalyst achieved >98% conversion of oleic acid to biodiesel at 70°C in 20 minutes.
• The catalyst demonstrated excellent stability, reusability, and phase transfer properties.

Conclusions:

• The synthesized TBA₆-P₂W₁₇-SO₃H is a highly efficient and stable solid acid catalyst for biodiesel production.
• The catalyst's phase transfer capability facilitates easy recovery and reuse without activity loss.
• This work presents a cost-effective strategy for large-scale biomass conversion applications.