Esterification of 1-hexene and acetic acid using resin-supported phosphotungstic acid catalysts

As an atom economy technology, the direct esterification reaction of olefins plays a significant role in the production of organic esters. In this work, a series of resin-supported HPW catalysts were prepared using D101, D152, RM027, and A15 as the carriers, and they were used to prepare 1-methylpentyl acetate by the esterification of 1-hexene and acetic acid. The composition, structure, morphology, acid content, and other parameters of catalysts were characterized. In the esterification reaction, the activity order of catalysts is as follows: 20.0%HPW/A15 > 20.0%HPW/D101 ≈ 20.0%HPW/D152 > 20.0%HPW/RM027. It depends on the acid strength of the carrier, the interaction between the carrier and HPW, and the HPW content. Moreover, it can be concluded that the weak acid resin carrier is completely inactive for the esterification reaction of 1-hexene, and the ratio of acetic acid to 1-hexene has a significant influence on the product selectivity. When n (acetic acid)/n (1-hexene) = 2, the optimum 1-methylpentyl acetate selectivity is 38.2%. Results of repeated experiments confirm that the stability of the active constituent is related to the type of functional groups on the carrier.