Nitrogen-doped rice husk ash as a support for nickel catalysts for carbon dioxide hydrogenation to methane

This work presents the synthesis of nickel catalysts for CO hydrogenation. The supports were prepared by thermal treatment of a mixture of rice husk, urea, and sodium bicarbonate at 500–700°С. The introduction of urea into the mixture promoted nitrogen doping of the support surface during calcination, affecting the textural and acid-base properties of the material. Nickel catalysts with a nominal metal content of 17% were synthesized by incipient wetness impregnation using a nickel(II) nitrate solution. One of the objectives of the study was to evaluate the effect of nitrogen doping on the dispersion and distribution of nickel particles. The prepared catalysts were tested in the CO methanation reaction, which allowed the relationship between the support preparation conditions and its catalytic activity to be determined. It has been shown that nickel catalysts for CO hydrogenation to methane can be synthesized using nitrogen-modified rice husk ash as a support.