Methanol synthesis from CO₂ and H₂ using supported Pd alloy catalysts.

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Methanol is a valuable chemical feedstock and energy carrier.
• Developing efficient catalysts for CO2 hydrogenation to methanol is crucial.
• Monometallic palladium catalysts exhibit limited selectivity for methanol production.

Purpose of the Study:

• To synthesize and evaluate palladium-based alloy catalysts for CO2 hydrogenation to methanol.
• To investigate the effect of alloying palladium with zinc and gallium on catalytic performance.
• To understand the structural and electronic properties influencing alloy formation and catalytic activity.

Main Methods:

• Synthesis of palladium-based catalysts (monometallic and bimetallic alloys).
• Evaluation of catalytic performance in CO2 hydrogenation to methanol.
• Characterization of post-reaction catalyst samples using techniques like XRD and surface analysis.
• Calculation of heats of mixing for various alloy compositions.

Main Results:

• PdZn and PdGa alloys demonstrated significantly enhanced methanol productivity over monometallic Pd catalysts.
• The 1:1 β-PdZn alloy was identified in post-reaction Zn-containing samples.
• The Pd2Ga alloy was formed in the Pd/Ga2O3 sample.
• Calculated heats of mixing indicated strong alloy formation for PdZn (-0.6 eV/atom) and Pd2Ga (-0.8 eV/atom).

Conclusions:

• Alloying palladium with zinc and gallium is an effective strategy to improve methanol selectivity and productivity.
• The preferential formation of PdZn over PdGa in the presence of Ga2O3 may be attributed to the lower reduction potential of ZnO compared to Ga2O3.
• These findings provide insights into catalyst design for efficient CO2 conversion to methanol.