Energy and environmental assessment of powder and structured Ni/GDC catalysts

Power-to-Gas technologies have been recently introduced as a relevant strategy allowing higher shares of renewablegeneration in the energy sector. In particular, the production of Substitute Natural Gas through the Sebatier reaction(CO2 + 4H2 ⇄ CH4 + 2H2O ΔH°298K = −165kJ/mol) (CO2 methanation) will allow to use the surplus of energyfrom RESs to produce H2, reducing the stress on the grid; to reduce CO2 emissions and at the same time toproduce SNG whose distribution infrastructures are readily available. Among the catalyst for CO2 methanation, Nibasedcatalysts supported on gadolinia-doped ceria (GDC) (Ni/GDC catalyst) demonstrated high potential for CO2methanation [1]. In order to assess the performance on the CO2 methanation, including besides chemical kineticsand productivity considerations also the environmental aspect, in this study the energy and environmental analysisof the production process of two Ni/GDC catalysts is performed through a life-cycle approach. Specifically, apowder Ni/GDC (50wt.%) catalyst synthesized by the solution combustion synthesis and the structured Ni/GDCcatalyst synthesized by the same method, in situ depositing the Ni/GDC (50wt.%Ni) coating layer on the cordieritemonolith (500 cpsi) are investigated. The analysis is carried out through the Life Cycle Assessment methodologyaccording to the international standard ISO 14040, assuming a “from cradle to grave” approach. The reference flowis represented by the amount of each catalyst needed to obtain a CH4 productivity of 2.5 4⁄( ∙ ℎ) at the sameoperation condition (reaction temperature of 300 °C and a space velocity (h) of 10,000 h-1).The eco – profiles of materials and energy sources are based on Ecoinvent 3 database. The impact assessment hasbeen performed considering the impact categories and methods recommended by the European ProductEnvironmental Footprint. The life cycle impact assessment results are recapped in Table 1.In this first analysis the production process of the structured Ni/GDC catalyst shows better environmental performance in allthe impact categories investigated compared to the powder Ni/GDC one. Therefore, besides guaranteeing better performancein the operational phase in terms of productivity, structured Ni/GDC catalyst could contribute in the improvement of the lifecycleimpacts of the methanation process.