Increasing in the Selectivity of Formose Reaction for Glyceraldehyde Production in the Presence of Fumed Silica and Montmorillonite Catalysts

In the present paper, the Formose reaction is investigated to produce polyols in the presence of two different catalysts at different pHs. The Formose reaction mechanism is the same as aldol condensation, which occurs in alkaline media and is accelerated by the presence of a heterogeneous catalysis. The products observed in the reaction medium are ethylene glycol, and glyceraldehyde. The present study shows that in the presence of fumed silica catalyst, increasing the pH from 7.6 to 9.3 reduces the production of ethylene glycol; however, it increases the conversion of ethylene glycol to glyceraldehyde. As a result, the amount of ethylene glycol in the reaction mixture decreases compared with neutral pHs. Nevertheless, the selectivity of the reaction to the production of glyceraldehyde increases. The same result can be observed when using montmorillonite as another heterogeneous catalyst. The difference is that the montmorillonite catalyst has less ability to accelerate the reaction than fumed silica. Also, at pH around 9 and above, practically no product is observed in the reaction medium.