Performance of carbon nanotubes as supports of nickel-iron catalysts for carbon dioxide methanation

Abstract

Nowadays, an increase in CO2 emission is one of the main reasons of global warming. Many studies have tried to solve the problem by developing catalysts to efficiently convert CO2 into CH4. Herein, bimetallic Ni-Fe catalyst was studied to improve the catalyst activity of Ni-based catalyst which has low activity and is easily deactivated. Carbon nanotubes (CNTs) have been identified as one of the most promising nanomaterials with unique electrical, thermal, and mechanical properties. In this thesis, CNTs was synthesized from eucalyptus oil as a renewable carbon source and then employed as catalyst support material in methanation. Variations of synthesis conditions indicated the optimal pyrolysis temperature (Tpyro) of 900 °C and molar ratio of eucalyptus oil and ferrocene (moil/fer) of 3:1 to obtain highest content of CNTs and highest thermal stability. The synthesized CNTs were impregnated with nickel and iron with different weight ratios to be catalyst for CO2 methanation. The 30wt% Ni-Fe/CNT with weight ratio Ni:Fe of 70:30 could provide the highest CO2 conversion and methane yield at reaction temperature of 325 °C and molar ratio CO2:H2:He of 1:4:5 due to its highest reducibility and synergistic effect of Ni and inherited Fe presence in synthesized CNTs.