Impact of the modification method of Ni/ZrO2 catalyst by alkali and alkaline earth metals on its activity in thermo-chemical conversion of cellulose

The goal of this work is to determine an impact of the modification method of Ni/ZrO₂ catalyst by alkali and alkaline earth metals on its activity in thermo-chemical conversion of cellulose to hydrogen-rich gas. Me_xO-ZrO₂ supports (where Me = Ca, Mg, Na or K) were prepared by impregnation, precipitation and sol-gel methods. The obtained results reveal that an introduction of dopants to the zirconia support considerably enhances the H₂ yield in comparison to unmodified catalyst. An increase in the hydrogen formation is accompanied by a rise in the total volume of the produced gases. It is demonstrated that the highest amount of hydrogen is formed in the presence of the catalysts containing CaO-ZrO₂ support followed by Na doped materials. This phenomenon can be attributed to more efficient incorporation of Ca²⁺ and Na⁺ cations in the zirconia lattice making it more stable in the reaction conditions. Moreover, it is observed that an activity order of the investigated catalysts is consistent with the changes in the basic character of their surface.