Magnesium Hydroxide Methoxide Nanostructures for Catalytic Aldol Condensation Reactions

The valorization of biomass into high-value chemicals via heterogeneous catalysis is a critical step toward sustainable chemical production. While acid catalysis has been extensively explored, basic catalysis remains underdeveloped due to challenges such as catalyst instability and energy-intensive activation. Here, we report the first use of nanostructured magnesium hydroxide methoxide Mg(OH)x(OCH3)2–x as a highly active, low-temperature basic catalyst for the aldol condensation of furfural with acetone, a key reaction for biofuel synthesis. The nanosized materials, synthesized via a scalable sol–gel route, exhibit exceptional specific surface areas (up to 825 m2 g–1) with mean nanosheets lateral size of ≈10 nm. They outperform conventional MgO and Mg(OH)2 catalysts (the conversion is multiplied by at least a factor of 5 under equivalent reaction conditions) under mild conditions (50 °C, atmospheric pressure) in a batch reactor, achieving 100% furfural conversion after only 30 min, with >70% selectivity toward the desired C13 product (F2Ac). The methoxy groups (−OCH3) are identified as the primary active sites, enabling high catalytic activity without thermal activation, unlike MgO. Systematic investigations reveal that material preparation parameters (H2O/Mg ratio, solvent, drying conditions) and storage atmosphere critically influence the material structure, stability and performance. Vacuum-dried samples retain superior activity due to minimized carbonate poisoning, while air-dried materials remain practical for industrial applications, balancing performance and cost. This work demonstrates that Mg(OH)x(OCH3)2–x is a promising nanocatalyst for sustainable biomass upgrading, offering a low-energy, scalable alternative to traditional basic catalysts.