Isopropylation of naphthalene with propene resulted in a variety of isomers having different alkylation levels.The most important isomer is 2,6-DIPN,which is the precursor of important monomer 2,6-naphthalene di- carboxylic acid used for making liquid crystal polymers.In order to increase the yield of 2,6-DIPN,the intermo- lecular transalkylation with naphthalene was applied to the mixture of other DIPNs and PIPN to obtain MIPN en- riched product,which underwent isopropylation with propene to produce 2,6-DIPN in a higher yield.The experi- mental study showed that the preferable conditions for transalkylation were reaction temperature of 325℃,the mo- lar ratio of isopropyl group to naphthyl group(IP/N)of 0.8︰1—0.9︰1,reaction time of 4h and 5%of amorphous silica-alumina by mass.The conversions of DIPN and PIPN in its mixture were 62%—69%and 87%—88%respec- tively and the yield of MIPN was greater than 40%.The mixture of MIPN enriched product and recovered MIPN from rectification was subject to isopropylation with propene at 275℃over a shape-selective catalyst to produce 2,6-DIPN in a yield up to 38%.A recycled process of recovered components was established,through one cycle the yield of 2,6-DIPN based on naphthalene may be 2.8 times higher than before,and the utilization ratio of raw naph- thalene was increased by 46%.
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