关键词: 水解, ZSM-5分子筛, 磷改性, 4-杂氧庚二醇

Abstract:

4-hexoheptanediol is an impurity in the production process of propylene glycol.It can be hydrolyzed to 1，3-propanediol through a catalytic hydrolysis reaction，thereby increasing the yield of propylene glycol.A phosphorus-modified ZSM-5 zeolite was prepared as a hydrolysis catalyst using the equal volume impregnation method.The structure，acidity，and the form of phosphorus in the zeolite of the catalyst samples were characterized by X-ray diffraction，³¹P solid-state NMR，and X-ray photoelectron spectroscopy respectively.The effect of phosphorus modification on its catalytic hydrolysis performance was studied through evaluation.The results showed that phosphorus modification significantly reduced the acid density of the ZSM-5 zeolite，and the trends of change for strong acid centers and weak acid centers were different.As the phosphorus content increased，the interaction between phosphorus and framework aluminum was gradually strengthened.When the phosphorus content was increased to more than 4%（mas fraction，the same below），the degree of phosphate polymerization was increased significantly.The proportion of P₂O₅ species on the surface of the ZSM-5 zeolite was firstly increased and then decreased with the increase in phosphorus loading.With the increase in phosphorus content in the ZSM-5 zeolite，the conversion rate of 4-hexoheptanediol was increased，while the selectivity of propylene glycol was firstly increased and then decreased.The optimal hydrolysis performance was achieved when the phosphorus loading was between 2% and 4%，and the phosphorus loading improved the hydrolysis stability of 4-hexoheptanediol on the ZSM-5 zeolite.

Key words: hydrolysis, ZSM-5 zeolite, phosphorus-modified, 4-hexoheptanediol