Application of corrosion-resistant Corning advanced-flow reactors for multiphase Bunsen reaction - Part two: investigation on multiphase reaction

Abstract

Bunsen reaction ( 2 H 2 O + I 2 + S O 2 → H 2 S O 4 + 2 H I ) is a key step for hydrogen production from either the H2S splitting cycle or the sulfur-iodine (S-I) cycle of water splitting. As pointed out in part one, when engineering this reaction, many challenges such as side reactions and corrosion impede scaling up this process. Using iodine-toluene solution to provide flowing iodine below the melting point of iodine renders the Bunsen reaction to be conducted at ambient temperature such that these challenges can be either overcome or eased. However, using toluene as the iodine solvent makes the Bunsen reaction a multiphase reaction system which includes gas, aqueous, and organic phases. Glass-made Corning® advanced-flowTM reactors (AFRs) can be used for Bunsen reaction because they are good at resisting corrosion, improving mixing efficiency of multiphase fluids, and allowing seamless scaling up. Part one has studied the absorption behavior of SO2 gas in the liquids used for Bunsen reaction (water, toluene and water-toluene mixture). Part two (this work) mainly studies the Bunsen reaction using the Corning® microscale (LF) and milliscale (G1) AFRs. When I2 was dissolved in toluene, the Bunsen reaction was conducted by feeding SO2 gas, water, and I2/toluene solution into the AFRs. SO2 and I2 were used as the limiting reactants in turn, and the effects of operating conditions such as gas and liquid flow rates, water to toluene ratio, and temperature in the range (22-80 oC) on the absorption rates of SO2 and the I2 reaction rate were studied. The results confirm the seamless scaling-up capability of the Corning reactors when the flow rates were increased twenty times from AFR-LF to AFR-G1.