Hydroxyl-mediated ethanol selectivity of CO₂ hydrogenation

Area of Science:

• Heterogeneous Catalysis
• Nanomaterials
• Green Chemistry

Background:

• Oxide-supported Rh nanoparticles are utilized for CO2 hydrogenation, primarily for ethanol synthesis.
• Current methods face challenges with high pressures (up to 8 MPa), low CO2 conversion, and poor alcohol selectivity.

Purpose of the Study:

• To investigate the role of hydroxyl groups on Rh-based catalysts supported on TiO2 nanorods (NRs) for CO2 hydrogenation.
• To enhance CO2 conversion and ethanol selectivity in the synthesis of ethanol.

Main Methods:

• Synthesis and characterization of Rh-based catalysts supported on TiO2 nanorods.
• Evaluation of catalyst performance in CO2 hydrogenation reactions under high pressure.
• Analysis of the reaction mechanism involving hydroxyl groups, formate species, and intermediate species.

Main Results:

• The RhFeLi/TiO2 NR catalyst exhibited superior reactivity with approximately 15% CO2 conversion.
• Achieved a high ethanol selectivity of 32% for CO2 hydrogenation.
• Demonstrated the crucial role of hydroxyl groups in stabilizing intermediates and promoting ethanol formation.

Conclusions:

• High Rh dispersion and abundant hydroxyl groups on TiO2 NRs synergistically enhance CO2 hydrogenation.
• Hydroxyl groups facilitate the stabilization of formate species and protonation of methanol, crucial for ethanol synthesis.
• The developed catalyst system offers a promising pathway for efficient ethanol production from CO2.