Based on the chemical equilibrium of the exothermal gas phase reaction network depicted in (RE1) -(RE3), the equilibrium reactor R1 is operated isobaric and isothermal at temperatures and pressures taken from experiments for Ru/Al2O3 catalysed CO2 methanation , as Alam et al. have done for their reaction conditions. Additionally, the chemical equilibrium calculation in Aspen HYSYS requires the choice of key reactions which are chosen to be (RE1) and (RE2).