Studies on esterification reaction over aluminophosphate and silicoaluminophosphate molecular sieves

Di-(2-ethylhexyl) phthalate (DEP) has been synthesized using a novel silico aluminophosphate molecular sieve CHSAPO-1 as catalyst for the esterificatio n reaction of phthalic anhydride with 2-ethylhexanol. The effect of some fa ctors such as reaction temperature, the molar ratio of 2-ethylhexanol/phtha lic anhydride, the amount of catalyst used, the amount of cyclohexane used and reaction time on the reaction has been investigated. The yield of di-(2 -ethylhexyl) phthalate obtained was over 95% when the reaction conditions u sed were as follows: the molar ratio of 2-ethylhexanol/phthalic anhydride = 2.8:1, the amount of cyclohexane used = 25 ml/mol phthalic anhydride, the amount of catalyst used = 1.1 g/mol phthalic anhydride, reaction temperatur e = 200-220 degreesC, and reaction time = 2 h. H-CHSAPO-1 catalyst also pos sesses high selectivity and good activity stability for the reaction. The p hysical properties of the esterified product synthesized are in accordance with the literature values. For comparison, some zeolites were also tested in the esterification reactions. Butyl pentanoate has also been synthesized by the esterification reaction o f pentanoic acid with n-butanol over novel aluminophosphate and silicoalumi nophosphate molecular sieves. The effect of the procedures of synthesizing the molecular sieves and preparing the catalysts, and reaction conditions o n the yield of the ester has been systematically investigated. The yield of the ester obtained when using aluminophosphate molecular sieves as catalys ts depends upon synthesis methods of the molecular sieves (mainly template and synthesis system). The aluminophosphate and silicoaluminophosphate mole cular sieves modified with Sn possess higher catalytic activity than those not modified. (C) 2001 Elsevier Science B.V. All rights reserved.