Synthesis Of Epoxy Plasticizer Catalyzed By HUSY/ZSM-5 Composite Zeolite

Epoxy plasticizer is a kind of plasticizer with epoxy groups in its molecular structure.The traditional production method using sulfuric acid as catalyst has the best performance among the synthesis methods of epoxy plasticizer,however,acid catalytic method has some problems such as environmental pollution and equipment corrosion.In recent years,epoxy plasticizers synthesis over solid acid catalysts instead of liquid acid has become a widely pursued goal in many research fields.Using of solid acid catalyst to catalyze the epoxidation of olefins not only reduces corrosion equipment and environmental pollution,but also allows the catalyst to be recycled and reused.In this paper,HUSY/ZSM-5 and HUSY/Silicalite-1 composite zeolites were prepared using MFI zeolite?ZSM-5 and Silicalite-1?to modify HUSY zeolite by hydrothermal crystallization method,their structure,acidity and morphology were characterized and analyzed by X-ray diffraction?XRD??N₂ adsorption-desorption?NH₃-TPD?Scanning Electron Microscope?SEM?and pyridine infrared?Py-FTIR?.The results showed that the synthesized composite zeolites have the dual structural characteristics of HUSY and MFI zeolite.It can be seen from the scanning electron microscope,the composite zeolite have a core-shell structure,and the smooth surface of the HUSY is covered by a phosphorus-like MFI zeolite.Compared with HUSY,the total acid amount of HUSY/ZSM-5 decreased after modified with MFI zeolite,whereas the amount of Br?nsted acid increased due to the formation of new Br?nsted acid sites.The catalytic performance of HUSY/ZSM-5 and HUSY/Silicalite-1 on the epoxidation reaction of soybean oil?SBO?and soybean oil methyl ester?SBME?was tested,and HUSY/ZSM-5 exhibited good catalytic activity.This is due to the fact that the shell ZSM-5 encapsulates the HUSY with a large amount of acid,which prevents the occurrence of side reactions of the epoxidation in the acidic system and effectively improves the selectivity of the epoxidation product.On the other hand,since the amount of Br?nsted acid is the main factor affecting the epoxidation reaction,some new Br?nsted acid sites formed in composited HUSY/ZSM-5 result in the increases of Br?nsted acid amount,which is beneficial to the epoxidation reaction.The effects of reaction temperature,reaction time,the amount on catalyst and oxidant on the epoxy reaction were discussed based on the acid value and epoxy value of the epoxy product,and the optimum conditions for the epoxidation reaction were obtained.The optimal reaction conditions for the epoxidation of soybean oil were as follows:soybean oil 20 g,acetic acid 4.0 mL,30 wt.%hydrogen peroxide 16 mL,HUSY/ZSM-5 3.0 g,reaction temperature 70°C,reaction time was 4.0 h,the acid value of the synthesized epoxidized soybean oil was0.46 mg/g,and the epoxy value was 5.60%.The optimum reaction conditions for the epoxidation of soybean oil methyl ester were as follows:soybean oil methyl ester 20 g,acetic acid 4.0 mL,30 wt.%hydrogen peroxide 18mL,HUSY/ZSM-5 2.0 g,reaction temperature 55°C,reaction time 3.0 h,synthetic soybean oil methyl ester acid value 0.71 mg/g,epoxy value 3.70%.The composite zeolite HUSY/ZSM-5 was regenerated by calcination.The catalytic activity of the zeolite after regeneration was not significantly reduced.After repeated use for 5 times,it still maintained good catalytic performance.Epoxy plasticizer products were characterized by FT-IR,¹H NMR and¹³C NMR,and it was confirmed that epoxy plasticizer products with high epoxy value,good stability and excellent quality were prepared under the optimal process conditions.