Liquid-phase solvent-less reactions for value addition of glycerol and phenols over nano porous aluminosilicates

The protocol reports an efficient nano porous solid acid catalyst for the effective conversion of bio-waste product glycerol and phenols into valuable chemicals and fuels through acetalization and alkylation reactions respectively. A novel method was adopted for the direct synthesis of the proton form of Aluminosilicate (H–Al–Si) from alkali-free gel medium for its ready catalytic applications towards bulky molecular reactions producing chemicals and fuels. In the liquid phase phenol alkylation reactions, the catalyst exhibited 83% conversion with 100% selectivity to the alkylated phenols at solvent-less reaction conditions. The catalyst also exhibited more than 90% conversion in glycerol acetalization reaction to produce mono, di and tri-acetalized esters useful for chemicals and fuel industries. Detailed physicochemical characterization of the synthesized material was conducted by XRD, BET, N₂-sorption, NH₃ TPD, FTIR, Raman, XPS, SEM, TEM, TG/DTA and Si²⁹ NMR spectroscopic techniques. XPS, FTIR, and NMR results indicated the formation of aluminosilicate chemical structure in the material while TPD confirmed the formation of strong acidity, TEM and sorption studies revealed the formation of ∼50 nm size particles of H–Al–Si material exhibiting nano porous nature make this nano porous material suitable for acid catalysed bulky molecular transformations exemplified by tert- butylation of phenol and glycerol acetylation. The promising performance of the catalyst towards these reactions was ascribed to the presence of nano size pores in the catalyst and the easy accessibility of the acid sites to the reactants and facile diffusion of the bulky product molecules. The catalyst also exhibited high temperature thermal stability in DT/TGA and structural stability of active sites revealed by stable catalyst performance with reaction cycles. Since, glycerol and phenolic compounds obtain from biomass needs to be addressed for effective value addition, the alkylation and esterification reactions catalysed by present catalyst system provides promising processes to produce valuable chemicals and fuels from low value bio-derivatives.