Abstract

Bunsen reaction (2H₂O + I₂ + SO₂ → H₂SO₄ + HI) is a key step for hydrogen production  from  either  the  H₂S  splitting  cycle  or  the  sulfur-iodine  (S-I)  cycle  of  watersplitting.  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.

Keywords

Bunsen reaction, H2S splitting cycle, hydrogen production, Corning® glass advanced-flowTM reactors