Study On Synthesis Of Propylene Glycol Monomethyl Ether With KF/AMO Solid Base As Catalyst

In this paper, a novel solid basic catalyst KF/AMO, which was suitable for the etherification reaction of propylene oxide with methanol to synthesize propylene glycol monomethyl, was obtained by loading KF on AMO supporter with water thermal treating. The effect of carrier pretreatment and loading conditions on this catalyst was inspected. The relevant reaction technology condition and the apparent activation energy was attained finally, also the reused property was studied.The framework of AMO carrier can not be changed after water thermal treating, however, new hydroxy formed on the carrier surface. In addition, the particle crystallinity strengthened , the particle specific surface ,average aperture and hole volume increased, and the crystal form got more integrated as well.The disperse threshold value of KF is 15% when AMO carrier is impregnated with KF at a appropriate temperature. Strong basicity is got after KF/AMO treated at the temperature between 300～400℃. The base amount that Hammet index Pka is above 10.0 of KF/AMO is 1.13mmol/gCat, and also the maximum base strength is 18.4. A good result is achieved by using KF/AMO as catalyst for synthesizing propylene glycol monomethyl ether.Under the optimized reaction conditions: reaction temperature between 120～130℃, catalyst concentration between 0.35～0.45%(wt), methanol/PO molar ratio between 5:1～6:1, reaction time between 100～120min, the conversion of propylene oxide is about 98%, the selectivity of propylene glycol monomethyl ether is higher than 95%, the yield of propylene glycol monomethyl ether is above 93%,and the selectivity of 1-methoxy-2-propanol is about 92～93%.At the temperature between 100～140℃, the apparent activation energy of solid basic catalyst KF/AMO for catalytic synthesizing propylene glycol monomethyl ether is 45.64kJ/mol. The catalyst can be reused directly for many times with no loss in activity and selectivity. Contrasting with solid acid catalyst, this product has high selectivity of 1-methoxy-2-propanol and low toxicity, which is better both in quality and environment for catalytic synthesizing propylene glycol monomethyl ether.