A CO2 valorization plant to produce light hydrocarbons: Kinetic model, process design and life cycle assessment

Reliable Life Cycle Assessment (LCA) of processes for valorization of CO2-rich off-gas streams requires multi-disciplinary contributions that span the development of active and selective catalysts, reactor design, plant modeling and optimization, as well as environmental impact analysis. Herein, we present the design and study of a CO2 valorization plant through methanol-mediated (tandem) hydrogenation to light hydrocarbons, with pro-pane as the most abundant product. A state-of-the-art PdZn/ZrO2 + SAPO-34 catalyst combination was screened for catalytic activity and selectivity in a wide operation range. Optimal process conditions were found at 350 degrees C, 30-40 bar and co-feeding of CO2/CO. Kinetic parameters for the tandem reaction were extracted and used for the design of a multi-layer reactor, where the two catalysts are distributed according to: (i) CO2-to-methanol catalyst; (ii) mixed catalyst bed, and; (iii) methanol-to-hydrocarbons catalyst. This configuration outperformed the con-ventional dual bed and mixed bed reactor configurations in terms of process design. A Life Cycle Assessment of the plant suggested that a substantial decrease in the global warming impact of propane production will be highly driven by using green hydrogen from either solar or wind sources, although the comparison with fossil -derived propane indicated already a reasonable improvement even when using grey hydrogen from natural gas.

Automated summary

A study on the conversion of CO2 to propane through catalytic reactions was conducted, and a corresponding reactor was designed. The use of an advanced catalyst combination achieved good catalytic performance under optimal conditions. Life Cycle Assessment suggested that the use of green hydrogen can significantly reduce the global warming impact of propane production.