(287a) Highly Efficient Synthesis of Liquefied Petroleum Gas (LPG) from CO2 Hydrogenation in a Na+-Gated Membrane Reactor

The rapid increase of CO₂ has been considered to result in the serious greenhouse effect globally. Direct transformation of CO₂ into value-added chemicals (e.g. hydrocarbons, methanol, DME) is very promising because it could not only mitigate the greenhouse effect but also make the use of fossil resources and biomass sustainable or carbon neutral. However, it is a challenge due to the kinetic and thermodynamic restrictions on CO₂ hydrogenation to liquefied petroleum gas (LPG). In-situ water removal by the novel water-conduction membrane lifts the restrictions for the high-yield direct synthesis of LPG from CO₂ and H₂ owing to the dry reaction environment, boosting the activity of the bifunctional catalysts and well protecting them from water “poisoning”. As a result, unprecedentedly high CO₂ conversion, product yield and exceptional durability at relatively mild conditions were achieved for CO₂ hydrogenation to liquid fuels and other reactions that are inhibited by water.

In this research, a highly water permselective NaA membrane, prepared on ceramic hollow fibers with secondary growth method, was investigated to selectively remove water from the reactions producing LPG from methanol route at the condition of 300°C and 20 bar. The membrane reactor loaded with a CuO–ZnO–ZrO₂–Al₂O₃ (CZZA)/Pd-β-zeolite bifunctional catalyst showed a CO₂ conversion of 90% and LPG yield over 60% with a stable performance for 200 hours. Moreover, the membrane reactor can reach equilibrium after about 1 h starting from ambient environment to the harsh reaction conditions (300°C and 20 bar). These results suggest that NaA membrane is capable of removing water in-situ in a membrane reactor, and thus increases the LPG yield at elevated temperatures and high pressures. We also expect NaA membranes to be used to increase the product yield of reactions with water as a by-product in a catalytic membrane reactor at harsh conditions.