The Preparation Of Supported Heteropolyacid Catalysts And Their Application In Hydroxyalkylation Of Phenol To Bisphenol F

Bisphenol F is an important chemical raw material that can be widely used in aviation, shipbuilding, electronic material and other manufacturing fields. However, bisphenol F and the related products in domestic market mainly rely on imports currently. The catalyst selection is of significant importance in the synthesis of bisphenol F. Herein, we are launching a research on novel heteropolyacid catalysts constructed with clay as starting material which is environment-friendly, cost-effective and available, because the involved liquid protonic acids used in conventional processes for the production of bisphenol F are of some drawbacks such as serious corrosion to equipment, difficult to separate and recover, more environmental problems and other issues. The samples were thoroughly characterized and their catalytic properties were explored in the hydroxyalkylation of phenol to bisphenol F. Listed below are the main contents:1) A series of catalysts were prepared by immobilizing PTA on BNT via impregnation method. Chemical compositions, textural properties and acid strength of the heteropolyacid catalysts were characterized. Besides, the reaction conditions for the synthesis of bisphenol F were optimized, and the effects of quantity of acid sites on the yield, selectivity, and isomer distribution were studied. The results showed that the total amount of weak and strong acid sites increased with the increase of PTA loading. Meanwhile, the catalytic performance was enhanced. When the load of PTA is 30%, the catalyst is the most efficient. Moreover, the quantity of strong acid sites is closely related to the percentage of 4,4'-isomer in products.2) For the first time, mesoporous material PTA/Al-MCM-41 was successfully fabricated via a facile one-pot hydrothermal approach by employing the natural clay BNT as silica and aluminum source material, CTAB as the template, and PTA as the active component. Elemental analysis, morphology structure and acid properties of PTA/Al-MCM-41 were characterized, and their catalytic properties were studied in the synthesis of bisphenol F. In the readily prepared composite, it seems that the PTA was encapsulated into and dispersed well in the Al-MCM-41 host, thus possessed good stability. It turned out that the process route is cost-effective, simple and green. The prepared catalysts also showed high catalytic activity, good reusability in bisphenol F production.3) Further study, especially the effects of acid sites and reaction temperature on the yield and 4,4'-isomer distribution were launched according to the results obtained when using PTA impregnated on BNT or PAL as catalysts. Moreover, the kinetics of the hydroxyalkylation of phenol to bisphenol F was established. The results showed that PTA/PAL had a better catalytic performance even under mild reaction conditions. To some extent, the increase of strong/weak sites ratio and reaction temperature could increase the percentage of 4,4'-isomer in products. Under the optimum conditions, the synthesis of bisphenol F followed pseudo-first-order kinetics.