Synergistic effect of freeze-drying and promoters on the catalytic performance of Ni/MgAl layered double hydroxide

Methane dry reforming is a potentially useful reaction but possesses some disadvantages such as catalyst deactivation by coking. Some new freeze-dried promoted-Ni/MgAl catalysts were used in this work for solving this drawback. The synergic effect of the freeze-drying method and incorporation of promoters was studied on physicochemical features of catalysts and catalytic performance. Field emission scanning electron microscopy images (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed that the Sr-promoted Ni/MgAl catalyst had a scaffold structure with desirable pores in contact with feedstock gases. The temperature-programmed reduction (H-2-TPR) and temperature-programmed deposition (CO2-TPD) techniques confirmed that the reduction behavior and basicity of the catalysts are affected by the type of promoter. In comparison to Y and Sr-promoted catalysts, the Sr-Ni/MgAl catalyst with the lower reduction temperatures, smaller Ni crystallite size, greater Ni dispersion, and higher basicity had the highest catalyst activity (72% CH4 conversion) and stability after 20 h time on stream without any carbon deposition. The higher basic cites resulted in eliminating coke specimens from the catalyst surface.

Automated summary

The study utilized freeze-dried promoted-Ni/MgAl catalysts to address catalyst deactivation by coking in methane dry reforming. By enhancing the basicity of the catalyst, the promotion led to higher activity and stability of the catalyst in conversion of methane, with the Sr-promoted Ni/MgAl catalyst demonstrating the best performance.