Synthesis and Characterization of Nickel Catalysts for Methane Tri-Reforming

Methane Tri-Reforming

Nicole Cordonnier

Ohio University

Advisor: Prof. Erdem Sasmaz, Prof. Jochen Lauterbach

The methane tri-reforming process is the combination of steam reforming, dry reforming, and partial oxidation of methane to form syngas with an H₂: CO ratio acceptable for the Fischer-Tropsch process. The tri-reforming process utilizes CO₂ in power plant flue gas, foregoing the usual pre-separation of CO₂. A tri-reforming catalyst must be stable at temperature up to 900°C, have a large surface area capable of storing large amounts of oxygen, and resist formation of coke. Coke formation, as well as sintering and agglomeration cause catalyst deactivation.

In this study, nickel nanoparticles were synthesized for use as catalysts in the tri-reforming process. The catalysts were synthesized using incipient wetness impregnation as well as micro-emulsion techniques to form core shell structures. Catalyst activity and stability were found to depend on both particle size and nonmetal oxide support.

Ni/CeO₂, Ni/MgO, Ni/SiC, and Ni/SiO₂ were synthesized using incipient wetness impregnation. Ni@CeO₂ and Ni@SiO₂ core shell particles were synthesized using emulsion techniques. Ni@SiO₂ particle sizes were controlled by changing the calcination temperature. Ni/CeO₂ and Ni/MgO were found to have the highest conversions with CO₂ conversions of 54% and 52% respectively, and CH₄ conversions of 98% and 97%. The core-shell catalysts were found to have less activity with a maximum CO₂ conversion of 34% for Ni@SiO₂ with a calcination temperature of 350°C. Lack of core shell activity can be attributed to instability of CeO₂ shell at high reaction temperatures. Particle agglomeration and sintering might also contribute to the deactivation resulting in increased particle size and decreased active surface area.