Effect of salts on the formation of THF in preparation of PBT by TPA process

The synthesis of poly(butylene terephthalate) from terephthalic acid, part I: The influence of terephthalic acid on the tetrahydrofuran formation

“…Various studies on the synthesis of PBT from terephthalic acid (TPA) and BD as a cheaper alterna-tive for the DMT-based process have been reported. [3][4][5][6] The major drawback of the TPA-based route and the main reason the DMT-based route is still used in most commercial plants is that approximately twice the amount of tetrahydrofuran (THF) is formed as a waste product, when TPA instead of DMT is used as a monomer for the synthesis of PBT. Consequently, to make the TPA-based synthesis of PBT more lucrative than the currently used DMT process, it is essential to reduce the amount of THF formed during the polymerization process.…”

Block copolyetherester. Part 3: Preparation of block copolyetheresters by a terephthalic acid process in the presence of salts

“…The reason for the reduction of the whole process time in the presence of the salt system was twofold. First, the esterification rate was enhanced in the presence of some salts (14) and the reaction time of the esterification stage could be reduced. Second, the conversion of esterification reached a higher value in the presence of the salt system, and this could reduce the reaction time of the polymerization stage.…”

“…The block copolyetherester was prepared by melt polycondensation of terephthalic acid, 1,4-butanediol, -and ITMEG1000, similar to a process for PBT described previously (14). The reactions of 166 g (1 .O moll of terephthalic acid, 162 g (1.8 mol) of 1,4butanediol, 123 g (0.123 moll of PTMEGlOOO in the presence of catalysts and various salts in a 1 L stainless steel reactor were carried out to evaluate the effect of the salts.…”

“…The reactions of 166 g (1 .O moll of terephthalic acid, 162 g (1.8 mol) of 1,4butanediol, 123 g (0.123 moll of PTMEGlOOO in the presence of catalysts and various salts in a 1 L stainless steel reactor were carried out to evaluate the effect of the salts. The content of THF of the distillate (containing water and THF) at the esterification stage and the conversion of esterification were determined as described previously (14). After the evaluation in the 1 L reactor, a better condition was chosen to scale up the process in a stainless steel pilot plant, which is composed of a 200 L esterification reactor and a 200 L polymerization reactor.…”

“…The situation may be simi-thalate) (PBT) by a TPA process in which the formation of tetrahydrofuran (THF) by cyclization is a severe problem. We have used some salts to reduce the formation of THF in the preparation of PBT by a TPA process, and some good results were found (14). In this study, we use some salts to improve the preparation of the block copolyetheresters by a TPA process, and a better condition was set up in a 200 L pilot plant to evaluate this modified TPA process.…”