Research On Catalytic Synthesis Of Nontoxic Plasticizer Citrate Ester

In this thesis, two types, six solid acid catalysts were synthesized and characterized. Their application in the catalytic preparation of citrate ester was investigated. The main contents of the thesis were as following.Solid acid catalysts of SO₄^2-/PGS and SO₄^2-/Al₂O₃ were prepared by modified palygorkite (PGS) and fibrous Al₂O₃ with low concentrated sulfuric acid, respectively. Their catalytic activity in the synthesis of trioctyl citrate was investigated. The yields were both above 92%.Pillared super solid acid catalysts of SO₄^2-/Fe-PGS, SO₄^2-/Fe-MMT and SO₄^2-/Al-PGS were prepared by inserting a Fe polycation and an Al polycation into montmorillonite(MMT) and palygorkite(PGS), and modified with sulfuric acid, Al polycation respectively. Their catalytic activity in the synthesis of trioctyl citrate was investigated. The yields were all above 90%. Especially, it's reached to 99% when SO₄^2-/Al-PGS is used as the catalyst. The advantages of those catalysts are facile preparation, low cost, high catalytic capability and little environmental pollution. But the loss of the activity is its defect, after recycling used for 6 times, the yield of trioctyl citrate fell to 87% for SO₄^2-/Al-PGS, others were even to 75%.Sulfonated phenolic resin was prepared by polymerized phenol with formaldehyde, and then modified with sulfuric acid. The use of sulfonated phenolic resin on the catalytic synthesis of tributyl citrate and trioctyl citrate was studied. The effects such as the mass of catalyst, the mole ratio of acid to alcohol, the reaction temperature as well as the reaction time were investigated. The yield of tributyl citrate and trioctyl citrate can be reached to 99% and 97%, respectively. The advantages of the resin catalyst synthesized are easy to prepare, recycling used, no environmental pollution and outstanding thermal stability.