(44c) Enhanced Reverse Water Gas Shift By Zeolite Membrane Reactor

Reverse water gas shift (RWGS) is attracting attention as one of the promising technologies for CO₂ conversion. Selective removal of H₂O from reaction system is able to improve the CO₂ conversion in RWGS. In this study, we developed the membrane reactor equipping zeolite membrane for selective dehydration.

MOR-type zeolite and CuO/ZnO/g-Al2O3 were employed as membrane and catalyst in the reactor. MOR membrane was prepared by a secondary growth method on an outer sureface of tubular support. A porous tubular a-Al₂O₃ with an outer diameter of 10 mm, an inner diameter of 7 mm and a length of 90 mm was used as support. The effective membrane area was 25.1 cm². CuO/ZnO/g-Al₂O₃ was prepared by a polymerized complex method. 3 g of catalyst was loaded around a tubular membrane. A reaction was carried out at 623 K at 1 atm with the feed gas of CO₂:H₂ = 1:3. A reaction was also conducted using a conventional reactor without membrane for comparison.

Although CO₂ conversion reached the ceiling at 30.1% in a reactor without membrane due to thermodynamic equilibrium limitation, CO₂ conversion successfully increased up to 70.6% by using a membrane reactor. The CO₂ yield, 70.6% is equivalent to the equilibrium conversion at 1005 K under the conditions. In other words, the membrane reactor succeeded in lowering the reaction temperature by 380°C.

Simulation study for RWGS membrane reactor was also conducted. A comparison of simulation study and experimental results will also be presented.