B-SBA-16 encaged functional tungstosilicic acid type ionic liquids to catalyze the ketal reaction†
There is special significance to composite catalysts using SBA-16 nano-cages as carriers in the acid catalysis field. A method for embedding boron atoms onto SBA-16 to increase acidic sites and enhance the acidity of the nano-cages was described. The tungstosilicic acid type ionic liquid (SWIL) was encaged into B-SBA-16 acidic nano-cages to obtain various composite catalysts. The acidic nano-cages and composite catalysts were characterized by FT-IR, TG/DSC, SAXD, BET, SEM, TEM, XPS and 1H NMR analyses. Research confirmed that boron was embedded onto the SBA-16 nano-cages in varying proportions and the obtained B-SBA-16 acidic nano-cages still maintained a high degree of pore ordering. The SWIL was successfully encapsulated into the acidic nano-cages via the immersion method. The cage-encapsulated tungstosilicic acid type ionic liquid catalysts SWIL/B(n)-SBA-16 were applied to catalyze the ketal reaction of cyclohexanone (CYC) with ethylene glycol (EG). The results showed that the conversion of CYC could reach 92.01% along with the yield of cyclohexanone ethylene glycol ketal (CGK) of 83.87% under ideal conditions. The CYC conversion was still nearly 86.86% and the CGK yield was 69.50% even after 8 times of continuous reuse.