Recently, researcher Fu Qiang of Dalian Institute of Chemical Technology and the team of Academician Bao Xinhe discovered that there is a classic strong metal-support interaction between the transition metal catalyst and the inert hexagonal boron nitride (h-BN) carrier. , SMSI), and the boron nitride carrier shows excellent performance in the dry reforming of methane and carbon dioxide (DRM). Monomer boron

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Popular science

Strong metal-support interaction (SMSI) is a common phenomenon in catalysis science. It means that under a certain atmosphere, the support will migrate and gradually wrap the metal catalyst, and the coating formed will modify the adsorption properties and electronic state of the active metal surface, thereby changing the catalyst. The response performance. Most of the time, because the surface active sites are covered by the coating, the catalyst in the SMSI state will be less efficient or even invalid.

Dry Reforming of Methane (DRM) can simultaneously convert two greenhouse gases into synthesis gas (CO+H2). Ni-based catalysts have both high efficiency, but need to be resolved under severe and long-term reaction conditions. The problem of catalyst sintering and carbon deposition.

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Boron Nitride Carrier

Hexagonal Boron Nitride (h-BN) is stacked successively by a layered structure similar to graphene. It has excellent mechanical properties, chemical and thermal stability, and is often used as a protective layer material under conditions. Therefore, in catalysis research, as a carrier, it is taken for granted that it is a material "inert" to the SMSI effect. However, when the researchers used the h-BN sheet material to support metallic Ni nanoparticles, they found that after 40 hours of catalyzing the DRM reaction, the surface of the h-BN nanosheets around the Ni nanoparticles was etched, and many nano-scale pits appeared. It shows that Ni and h-BN have an interaction process in the DRM reaction atmosphere.

Different from the dense oxide package in the traditional SMISI effect that inhibits the catalytic reaction, the SMSI effect in the h-BN system also has its own characteristics. Because the oxide of boron is often in an amorphous structure, and the working temperature of the DRM reaction (750oC) ) Is also higher than its melting point. Therefore, the BOx coating layer is in an amorphous state under the reaction conditions and has strong fluidity, which may be beneficial for the reactant molecules to contact the metal surface and be activated.

Summary

Researchers found that only in an atmosphere with moderate oxidizing power such as CO2 and H2O, can the h-BN be etched. No etching occurred in a strong reducing atmosphere (such as H2 and CO), or a strong oxidizing atmosphere (such as O2). The SMSI effect in the h-BN system is also universal, and similar phenomena can also be extended to metal catalysts such as Fe, Co, Ru and Pt. It can be seen that boron nitride is used as a catalyst carrier in specific application scenarios!