Highly stable and anti-coking Ni/MoCeZr/MgAl2O4-MgO complex support catalysts for CO2 reforming of CH4: Effect of the calcination temperature

Abstract

Catalyst deactivation by coking and sintering over Ni-based catalysts is still an open question for carbon dioxide reforming of methane (CDRM). Here, Ni/MoCeZr/MgAl2O4-MgO complex support catalysts were successfully synthesized by calcination of the Ce, Zr and Mo promoted NiMgAl-hydrotalcite-like precursors using a simple one-step co-precipitation method. Particular attention was paid to the anti-coking properties and catalytic behaviors of these complex support catalysts prepared at different calcination temperatures (700, 800 and 900 °C). Under harsh conditions (at 900 °C under GHSV of 60,000 mL·h−1·gcat−1 and without using inert gases as diluents), the catalyst calcined at 800 °C yielded a high conversion of CH4 and CO2 above 95% and long-term stability for 658 h without any remarkable coke deposition (only 0.015 mgC·h−1·gcat−1), outperforming the catalysts obtained at other calcination temperatures. Coking analysis showed that all the catalysts generated negligible coke deposition, indicating that solving the coke deposition problem puzzled researchers for many years is possible. Further analysis revealed that the generation of small Ni nanoparticles (<9 nm), strong basicity and intimated metal-support interactions coupled with the high reaction temperature might be the reasons for the stable coke-free process. This work may serve as an important reference for other kinds of catalysts suffering deactivation due to coking and/or sintering.