(500g) Dehydration Membrane Reactor for the Production of Valuable Chemicals from CO2 and H2

Production of liquid fuels or chemicals from captured and removed CO₂ and renewable H₂ presents a new approach to producing clean, low-carbon fuels domestically. While significant progress has been made in renewable electricity generation from solar and wind, many processes for producing liquid fuels/chemicals from renewable electricity are constrained by thermodynamic limitations, making them prohibitively expensive and impractical. We are overcoming these limitations and developing catalytic membrane reactor processes with high yields and low energy penalties. We developed a technology for the production of renewable liquefied petroleum gas (rLPG) from CO₂ and H₂ using a novel catalytic membrane reactor. Due to its environmentally benign characteristics, LPG is being used as a clean fuel in heating appliances, cooking equipment, and vehicles. Global LPG production was approximately 330 million tonnes in 2022. By producing rLPG through the catalytic conversion of captured CO₂ and renewable H₂, this process will produce renewable liquid transportation and heating fuels and a means of large-scale utilization of captured CO₂.

In our LPG synthesis process, CO₂ and H₂ are fed to a hollow-fiber, catalytic membrane reactor, at 20-35 bar and 220-320°C. The reactor contains a bi-functional catalyst that promotes two reactions, methanol (MeOH or CH₃OH) synthesis (CO₂ + 3H₂ ⇋ CH₃OH + H₂O) and LPG synthesis (MeOH ⇋ hydrocarbon pool ⇋ LPG + H₂O), into a one-step process to produce LPG. A Cu/ZnO/ZrO₂/Al₂O₃ (CZZA) catalyst is used for methanol synthesis and is coupled with a Pd-β zeolite catalyst for LPG production. However, combining these two reactions results in increased water production which inhibits catalytic activity. Here, our recently developed Na⁺-gated, water-transport membrane (Science, vol. 367, pp. 667, 2020) removes water in situ, shifting the thermodynamic equilibrium towards product formation while decreasing kinetic inhibition from water adsorption onto the catalyst surface. Our membrane showed H₂O/CO₂, H₂O/H₂, H₂O/CO, and H₂O/MeOH selectivities of 560, 190, 170, and 80, respectively. In laboratory-scale testing using this membrane reactor, the one-pass LPG yield of 60.5% with a CO₂ conversion of 90.2% was achieved, which significantly exceeds the literature results of traditional packed-bed, catalytic reactors.