Continuous synthesis of tributyl phosphate in microreactor

Abstract

Tributyl phosphate (TBP) is the most widely used extractant in the nuclear fuel cycle. It is used both in the front-end and back-end of the nuclear fuel cycle for separation and purification of nuclear materials. It is also used for solvent extraction of other metal ions such as lithium, cobalt and nickel. Synthesis of TBP involves highly exothermic reaction of n-butanol with phosphorus oxychloride. It is conventionally carried out using a batch/semi-batch process. We report, for the first time, a continuous method to synthesize TBP in a microreactor. The product yield was observed to increase with an increase in the residence time and the reaction temperature.100% yield was obtained for a residence time of 44 min at reaction temperature of 60 °C in the microreactor having a T-junction micromixer. The space-time-yield and production rate at these conditions were 13270.67 kg/day-m3 and 41.02 gm/day, respectively. Two different types of micromixers (T-junction micromixer and split-and-recombine micromixer) were compared. CFD simulations to quantify mixing in micromixers were also performed to have more insights into the experimental trends.