Heterobimetallic Iridium-Niobia Catalyst for Efficient and Selective Methane Ammonia Reforming

Area of Science:

• Heterogeneous catalysis
• Materials science
• Surface chemistry

Background:

• Developing efficient catalysts for methane/ammonia reforming is crucial for sustainable energy.
• Traditional catalyst preparation methods often lack atomic-level control, limiting performance.

Purpose of the Study:

• To synthesize a mesoporous SBA-15 silica-supported Ir-NbO_x catalyst using a Surface OrganoMetallic Chemistry (SOMC) approach.
• To evaluate the catalytic performance of the Ir-NbO_x/SiO₂ catalyst in selective methane/ammonia reforming.
• To elucidate the synergistic effects between iridium and niobium oxide sites.

Main Methods:

• Utilized a Surface OrganoMetallic Chemistry (SOMC) approach with a molecularly defined heterobimetallic niobium-iridium complex.
• Prepared a mesoporous SBA-15 silica-supported Ir-NbO_x catalyst.
• Compared the performance of Ir-NbO_x/SiO₂ with Ir/SiO₂ and NbO_x/SiO₂ analogs, as well as a conventionally prepared Ir-NbO_x/SiO₂ reference catalyst.

Main Results:

• The SOMC-prepared Ir-NbO_x/SiO₂ catalyst exhibited significantly higher activity (turnover frequency 8.5 s^-1) and selectivity (75%) in methane/ammonia reforming compared to Ir/SiO₂.
• The catalyst demonstrated tuned selectivity towards C-H activation over C-C cleavage in ethane/ammonia reforming, attributed to Ir/NbO_x synergy.
• A reference catalyst prepared by conventional methods was inactive, underscoring the efficacy of the SOMC approach.

Conclusions:

• The SOMC approach enables the preparation of highly active and selective Ir-NbO_x/SiO₂ catalysts for methane/ammonia reforming.
• Atomic-scale synergy between Ir and NbO_x sites is key to achieving enhanced catalytic performance.
• This study highlights a significant advancement in catalyst design for selective C-H activation.