Techno-economic evaluation of preparing high-valued TPAOH from its low-cost bromide via electrodialysis metathesis (EDM)

Abstract High-purity and low-cost tetrapropyl ammonium hydroxide, denoted by TPAOH, is of significance for industrial applications of high-performance Titanium-Silicalite-1 molecular sieve catalyst. For the first time, the electrodialysis metathesis, abbreviated to EDM, was proposed to prepare high-valued and high-purity TPAOH from its bromide and effects of operation conditions including initial feed concentration, operation voltage, and flowrate on the techno-economic availability of EDM were systematically investigated. Results showed that increasing initial feed concentration could result in higher production capacity and TPAOH purity, but lower current efficiency and higher energy consumption; higher feed initial concentration was more preferable concerning maximum economic benefit. The optimal operation voltage of 4.5 V was observed to achieve highest production capacity, current density, and product purity. Based on experimental results, estimated maximum economic benefit can also be obtained at the operation voltage of 4.5 V. The highest current efficiency, lowest energy consumption, and maximum economic benefit occurred at the flowrate of 100 ml/min under the current experimental scale. Meanwhile, the product purity can be enhanced by increasing the flowrate when product purity is in the first place. Compared to other technologies, preparing TPAOH via EDM showed lower energy consumption and higher product purity, thereby rendering superior techno-economic advantages.