Thermally Stable High-Entropy Layered Double Hydroxides for Advanced Catalysis.

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Layered double hydroxides (LDHs), particularly high-entropy variants (HE-LDHs), are gaining attention for catalytic applications.
• A key limitation of HE-LDHs is their poor thermal stability, hindering their use in high-temperature processes like thermo-catalysis.

Purpose of the Study:

• To develop a novel method for enhancing the thermal stability of HE-LDHs.
• To investigate the impact of this enhanced stability on their performance in fuel oil purification via thermo-catalytic oxidation.

Main Methods:

• A complexing nucleation method was employed to precisely control the nucleation of metal ions with varying solubility products.
• This method promotes homogeneous nucleation, preventing phase segregation and transformation at elevated temperatures.
• The thermal stability and catalytic activity of the engineered HE-LDHs were evaluated.

Main Results:

• The engineered HE-LDHs demonstrated exceptional thermal stability, remaining stable up to 300°C, surpassing previously reported LDHs.
• These HE-LDHs retained both Lewis and Brønsted acidic sites, crucial for catalytic activity.
• 100% removal of aromatic sulfides and alkaline nitrogen compounds from fuel oils was achieved in thermo-catalytic oxidation reactions.
• Strengthened metal-hydroxide bonds and negative thermal expansion contributed to structural stability and enhanced catalytic performance.

Conclusions:

• A novel complexing nucleation strategy effectively engineers HE-LDHs with remarkable thermal stability.
• The enhanced HE-LDHs show significant promise for applications in thermo-catalysis, particularly for fuel oil purification.
• This work provides a pathway for designing stable and active LDHs for demanding catalytic applications.