Design and optimization of NiMg/ceria-zirconia catalyst pellets

Mechanical strength plays a significant role in the industrial applications of the solid catalysts. Often powder catalysts must be “formed” into pellets to meet pressure drop restrictions in packed tubular reactors. The pellets must be designed to be mechanically stable when subjected to thermal and mechanical stresses during operation. The objective of this study was to evaluate the effect of powder processing parameters on mechanical stability of the resulting extruded cylindrical NiMg/Ce_0.6Zr_0.4O₂ pellet catalysts. The binder amount, water amount, and pH of solvent impacted physicochemical properties and mechanical strength of the catalysts. Optimal amounts of binder and water, as well as a low slurry pH can increase the crush strength and breakage resistance. An enhancement in mechanical strength of 220% was obtained by optimizing the binder to solvent ratio and pH conditions. The tri-reforming performance (e.g., CH₄ and CO₂ conversions, and H₂/CO molar ratio) was minimally impacted when the powder processing was optimized to improve mechanical strength.