General Strategy toward Hydrophilic Single Atom Catalysts for Efficient Selective Hydrogenation

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Hydrophilic single-atom catalysts (SACs) are crucial for selective hydrogenation in hydrophilic solvents.
• Existing SACs often lack stability and dispersibility in such media, limiting their application.
• Developing robust SACs is essential for synthesizing important chemicals and pharmaceutical intermediates.

Purpose of the Study:

• To develop a general strategy for fabricating stable and hydrophilic single-atom catalysts.
• To demonstrate the efficacy of these SACs in selective hydrogenation reactions within hydrophilic solvents.
• To investigate the catalytic performance of Ni1/TiO2 SACs for a specific hydrogenation reaction.

Main Methods:

• A cation-exchange approach was employed using metal ions (Ni, Fe, Co, Cu) and Na+ within TiO2 or ZrO2 nanoshells.
• The cation exchange prevents metal ion aggregation, forming M1/TiO2 and M1/ZrO2 SACs.
• Catalytic activity was tested using Ni1/TiO2 for the selective hydrogenation of cinnamaldehyde.

Main Results:

• The fabricated SACs exhibit excellent dispersibility and stability in hydrophilic solvents like alcohol and water.
• Ni1/TiO2 SACs achieved 98% conversion and over 90% selectivity for phenylpropanal production from cinnamaldehyde.
• The catalyst demonstrated good recyclability and a high turnover frequency (TOF) of 102 h-1.

Conclusions:

• The cation-exchange method provides a general route to highly dispersible and stable hydrophilic SACs.
• These SACs significantly facilitate catalytic reactions in alcohol, outperforming many existing catalysts.
• The developed Ni1/TiO2 SAC represents a highly efficient catalyst for selective hydrogenation, including compared to noble metal catalysts.