In situ DRIFTS and DFT study of CO₂ hydrogenation over the In₂O₃ catalyst

Area of Science:

• Catalysis
• Chemical Reaction Engineering
• Materials Science

Background:

• Carbon dioxide (CO2) hydrogenation is a key process for converting greenhouse gases into valuable chemicals.
• Indium oxide (In2O3) has shown potential as a catalyst for CO2 hydrogenation, but its reaction mechanism requires detailed investigation.
• Understanding the influence of reaction conditions, such as pressure, is crucial for optimizing catalytic performance.

Purpose of the Study:

• To investigate the pressure-dependent reaction mechanism of CO2 hydrogenation over an In2O3 catalyst.
• To elucidate the factors controlling the selectivity towards methanol versus carbon monoxide (CO) formation.
• To identify the key intermediates and rate-limiting steps in the CO2 hydrogenation pathway.

Main Methods:

• Experimental investigation of CO2 hydrogenation over In2O3 at varying pressures.
• Analysis of reaction products to determine selectivity.
• Computational or mechanistic studies to understand intermediate transformations (e.g., formate route).

Main Results:

• Methanol is selectively produced only at high pressures during CO2 hydrogenation over In2O3.
• At atmospheric pressure, the primary product is carbon monoxide (CO).
• The conversion of the formate intermediate (HCOO* to H3CO*) is significantly accelerated at high pressures.

Conclusions:

• The reaction pressure critically influences the selectivity of CO2 hydrogenation over In2O3.
• The formate route (CO2* → HCOO* → H3CO* → H3COH) is favored for methanol formation under high pressure conditions.
• Optimizing pressure is essential for directing the reaction towards methanol synthesis.