Study On The Preparation Of Modified Clay Solid Acid Catalyst And Applied In Trioctyltrimellitate Synthesis

Esterification of carboxylic acids is one of the fundamental reactions in organicchemistry, conventional catalysts are corrosive and virulent, so they need to beneutralized after the completion of the reaction. Because of its advantages of abundantreserves, low prices and the stability of the physical and chemical properties, thedifferent solid acid catalyst prepared from clays attracted extensive attention. Basedon the review of the TOTM and the properties and the applications of palygorskitesolid acid catalyst, The article research on catalytic synthesis of TOTM by severalmodified clay solid acid catalysts, the dissertation of included following contents:1. Palygorskite（PGS）supported TiO₂is prepared by dipping method of acidactivated palygorskite, and then it is modified by H₂SO₄to achieve the SO₄^2-/TiO₂-PGS solid super acid. The catalyst is characterized by FT-IR, XRD spectroscopy,SEM and BET. It is applied in trioctyl trimellitate synthesis． The orthogonalexperiment shows that the esterification yield is94.15%under the conditions： themolar ratio of trimellitic anhydride to2-ethylhexyl alcohol is1:4.5, the weight ofcatalyst is3.7％of total weight, the reaction time is6h and the oil bath temperature isat210℃．2. The solid acid catalyst PGS-SO₃H mesoporous silica functionalized withsulfonic acid group were prepared by post-synthesis methods. The samples werecharacterized by such methods as the IR, XRD, TEM, TG and were tested in theesterification reaction of trioctyl trimellitate. Under the optimal reaction conditions ofthe reaction temperature is at210℃,the molar ratio of trimellitic anhydride to2-ethylhexyl alcohol is1:4.5, the weight of catalyst is4.9％of total weight, thereaction time is6h,the esterification rate were96.16%.3. The surface of acid-activated palygorskite （Pa） was modified by graftingMPTMS and silane coupling agent for preparation into a hydrophobic bifunctionalmesoporous solid acid catalysts. The samples were characterized by IR,XRD,TEM,TG,and elemental analysis. The catalytic activity of the materials was tested for theesterification of trimellitic anhydride with2-ethyl hexanol. Both Si（CH₃）₃-PGS-SO₃H and C₁₆H₃₃-PGS-SO₃H showed high and specific catalytic activity on the first use.Due to its unique properties, low cost and ready availability, Si（CH₃）₃-PGS-SO₃H andC₁₆H₃₃-PGS-SO₃H provides a satisfactory option for catalyzing esterificationreactions.