Sustainable\nSynthesis of Single-Phase Ba<sub>3</sub>MgSi<sub>2</sub>O<sub>8</sub> Nanoparticles Using Sporopollenin for\nFructose Syrup Production: DFT and Quantitative NMR Insights on Glucose\nIsomerization

Producing high fructose syrup (HFS) is essential for\nboth the platform\nchemicals and food industries. While enzyme-based methods are commonly\nused, their limited availability has led to growing interest in alkali\nmetal catalysts. However, a complete understanding of these catalysts’\nmechanism is still needed. Traditional alkaline earth metal oxides\nsuffer stability issues due to metal leaching from solid surfaces.\nWhile Ba<sub>3</sub>MgSi<sub>2</sub>O<sub>8</sub> (BMS) is well-studied\nfor its phosphor nature, its use as a Lewis base catalyst has not\nbeen explored. We present a novel method for the synthesis of BMS\nnanoparticles and demonstrate its application as a Lewis base for\nglucose to fructose (GLU-FRU) isomerization. In contrast to the conventional\nhigh-temperature solid-state grinding (1225 °C) of BaCO<sub>3</sub>, MgO, and SiO<sub>2</sub>, we synthesized crystalline single-phase\nBMS nanoparticles from BaCl<sub>2</sub> and hydrous magnesium silicates\nencapsulated in sporopollenin (BMS-ES2), utilizing a coprecipitation\nmethod at 400 °C. We attained a remarkable 62% glucose conversion\nrate, resulting in 56% fructose yield with 90.3% selectivity at 90\n°C in 60 min at 25% glucose loading in H<sub>2</sub>O, marking\nthe highest reported values among catalysts containing alkaline earth\nmetals in water. Further investigation using NMR and DFT revealed\na proton exchange mechanism favoring Ba(OH)<sub>2</sub> due to water\ndissociation at Ba sites over Mg sites. The catalyst displayed excellent\nreusability, with a minimal 2–4% yield decrease per cycle over\nfive cycles. These results not only provide insights into sustainable\nsynthesis methods for Ba<sub>3</sub>MgSi<sub>2</sub>O<sub>8</sub> but\nalso illuminate its catalytic properties for base-catalyzed reactions\nand the proton exchange mechanism involved in GLU-FRU isomerization.\nBa<sub>3</sub>MgSi<sub>2</sub>O<sub>8</sub> nanoparticles are sustainably\nsynthesized from biomass waste and catalyze gram scale GLU-FRU conversion\nin water with excellent selectivity and reusability.