The Research On Synthesis Of Bisphenol F Catalyzed By 12-Phosphotungstic Acid Supported On Palygorskite

Bisphenol F is an important chemical intermediate for the industrial preparation of epoxy resin and polycarbonate. Bisphenol F epoxy resin possesses most of the advantages of bisphenol A epoxy resin and has lower dynamic viscosity than bisphenol A epoxy resin. Due to its low viscosity, there is no need to add extra additive to lower its viscosity when bisphenol F epoxy resin is applied, especially in electronics field.Conventionally, the hydroxyalkylation processes like bisphenols are produced through acid-catalysed condensation reaction by using liquid protonic acid(e.g. HCl,H3PO4, H2SO4, etc.) as catalysts. However, the use of homogeneous acid catalysts are limited with several environmental problems, such as corrosion, high toxicity,difficulties in separation and recovery of pure product. Heterogeneous solid catalysts is a good solution to these problems. Heteropoly acid possesses the strong Br?nsted acidity, large anion size, low charged density, hence it shows stronger acidity than mineral acid. Nevertheless, the low surface area(< 10 m2/g) failed its application in catalytic field. The heteropoly acid supported on a suitable effective support can greatly improve the specific surface area, the catalytic activity. The brief contents are shown as follows:Firstly, Phosphotungstic acid as acid active center was loaded on palygorskite using impregnation. The crystal structure, special surface area and the acid concentration of the catalysts were characterized by FT-IR, XRD, BET, NH3-TPD,EDX.Secondly, the activity of the catalysts for synthesis of bisphenol F was evaluated.The factors of the phosphotungstic acid concentration, reaction temperature, time,phenol/formaldehyde mole ratio and catalyst concentration, which affected the yield and selectivity of bisphenol F were investigated. The best condition of the synthesis of bisphenol F is reaction temperature 343 K, reaction time 40 min, phenol/formaldehyde mole ratio 15:1, mcatalyst/mreactants = 0.006 g/g and the yield and selectivity of bisphenol F is 89% and 96%.Thirdly, palygorskite was modified with(3-aminopropyl)triethoxysilane, then phosphotungstic acid(20%) was dispersed on silylated palygorskite which showed brilliant stability in the recycling with 85% yield and 97% selectivity at the first use,82% yield and 96% selectivity after 4 recycles.