Formic acid dehydrogenation using Ruthenium-POP pincer complexes in ionic liquids

Area of Science:

• Catalysis
• Hydrogen Storage
• Organometallic Chemistry

Background:

• Formic acid is a promising liquid hydrogen storage medium.
• Efficient dehydrogenation catalysts are crucial for its practical application.
• Ruthenium pincer complexes are effective catalysts for this transformation.

Purpose of the Study:

• To synthesize and evaluate new ruthenium pincer complexes for formic acid dehydrogenation.
• To investigate catalytic performance under mild, reflux-free conditions.
• To identify highly active and selective catalysts for hydrogen production.

Main Methods:

• Synthesis of ruthenium pincer complexes with xantphos-type POP ligands.
• Catalytic dehydrogenation of formic acid in ionic liquid (BMIM OAc) solvent.
• Analysis of gas products (CO2, H2, CO) using mass spectrometry.
• Determination of conversion and turnover frequency.

Main Results:

• Complexes of the general formula [RuHCl(POP)(PPh3)] were synthesized.
• The literature complex Ru-1 achieved a maximum turnover frequency of 4525 h⁻¹ with 74% conversion in 10 min.
• The novel complex Ru-2 demonstrated full conversion within 1 h, with activity observed as low as 60 °C.
• No carbon monoxide (CO) was detected, indicating high selectivity.

Conclusions:

• New ruthenium pincer complexes are effective catalysts for formic acid dehydrogenation.
• The novel complex Ru-2 offers excellent performance under mild conditions.
• These findings advance the development of efficient hydrogen storage systems using formic acid.