Enhanced carbon tolerance of hydrotalcite-derived Ni-Ir/Mg(Al)O catalysts in dry reforming of methane under elevated pressures

Pressurized dry reforming of methane (DRM) is highly desirable in terms of economy and efficiency, but imposes increased risk of catalyst carbon deposition. Here, hydrotalcite-derived Ni-Ir/MgAl(O) catalysts with various Ir/ Ni molar fractions (0, 5, 10, 15, 20, 25 and 30%) have been successfully prepared by one-step co-precipitation method. The promoting effect of Ir on the catalytic performance of catalysts in pressurized DRM was focused. After adding Ir, the catalyst stabilities (reflected by the deactivation degree) were significantly improved and were comparable when the amount of Ir was high (>= 15%). Long-term stability for 180 h at 1.0 MPa and 850 ?C under 60,000 mL.g(cat)(-1).h(-1) was achieved on catalyst 100Ni20Ir, and the final CH4 conversion was still above 68.5%. Detailed characterizations disclosed that the addition of Ir favored the formation of smaller Ni particles and enhanced the carbon tolerance properties of catalysts. The effective inhibition of the formation of encap-sulated graphitic carbon and better carbon nanotubes removal characteristics were responsible for the enhanced carbon tolerance behaviors. The carbon deposition, especially the encapsulated graphitic carbon, was proved to be the major cause of catalyst deactivation. Our findings bring us one step closer to developing durable and coke-resistant catalysts suitable for high pressure DRM.

Automated summary

Pressurized dry reforming of methane (DRM) is highly desirable for its economic and efficient benefits, but the risk of catalyst carbon deposition is a concern. This study explored the use of hydrotalcite-derived Ni-Ir/MgAl(O) catalysts with different Ir/Ni molar fractions to enhance stability and carbon tolerance in pressurized DRM reactions. The addition of Ir was found to improve catalyst performance and inhibit carbon deposition, leading to improved durability and resistance to coke formation in high pressure DRM processes.